Merge branch 'master' into AX25_FM

Add some delay to squelch

AX25Defines.h

@@ -0,0 +1,36 @@
+/*
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#if !defined(AX25DEFINES_H)
+#define  AX25DEFINES_H
+
+const uint8_t AX25_RADIO_SYMBOL_LENGTH = 20U;      // At 24 kHz sample rate
+
+const uint8_t AX25_FRAME_START = 0x7EU;
+const uint8_t AX25_FRAME_END   = 0x7EU;
+const uint8_t AX25_FRAME_ABORT = 0xFEU;
+
+const uint8_t AX25_MAX_ONES    = 5U;
+
+const uint16_t AX25_MIN_FRAME_LENGTH = 17U;        // Callsign (7) + Callsign (7) + Control (1) + Checksum (2)
+
+const uint16_t AX25_MAX_FRAME_LENGTH = 330U;       // Callsign (7) + Callsign (7) + 8 Digipeaters (56) +
+                                                   // Control (1) + PID (1) + Data (256) + Checksum (2)
+
+#endif
+

AX25Demodulator.cpp

@@ -0,0 +1,314 @@
+/*
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *   Copyright 2015-2019 Mobilinkd LLC <[email protected]>
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "Config.h"
+#include "Globals.h"
+#include "AX25Demodulator.h"
+#include "AX25Defines.h"
+
+const float32_t SAMPLE_RATE = 24000.0F;
+const float32_t SYMBOL_RATE = 1200.0F;
+
+const uint16_t DELAY_LEN = 11U;
+
+const float32_t SAMPLES_PER_SYMBOL = SAMPLE_RATE / SYMBOL_RATE;
+const float32_t PLL_LIMIT          = SAMPLES_PER_SYMBOL / 2.0F;
+
+const uint32_t LPF_FILTER_LEN = 48U;
+
+q15_t LPF_FILTER_COEFFS[] = {
+    -2,   -8,  -17,  -28,  -40,  -47,  -47,  -34,
+    -5,   46,  122,  224,  354,  510,  689,  885,
+  1092, 1302, 1506, 1693, 1856, 1987, 2077, 2124,
+  2124, 2077, 1987, 1856, 1693, 1506, 1302, 1092,
+  885,  689,  510,  354,  224,  122,   46,    -5,
+  -34,  -47,  -47,  -40,  -28,  -17,   -8,    -2
+};
+
+// Lock low-pass filter taps (80Hz Bessel)
+// scipy.signal:
+//      b, a = bessel(4, [80.0/(1200/2)], 'lowpass')
+//
+const uint8_t PLL_IIR_SIZE = 5U;
+
+const float32_t PLL_LOCK_B[] = {
+    1.077063e-03,4.308253e-03,6.462379e-03,4.308253e-03,1.077063e-03};
+
+const float32_t PLL_LOCK_A[] = {
+    1.000000e+00,-2.774567e+00,2.962960e+00,-1.437990e+00,2.668296e-01};
+
+// 64 Hz loop filter.
+// scipy.signal:
+//      loop_coeffs = firwin(9, [64.0/(1200/2)], width = None,
+//          pass_zero = True, scale = True, window='hann')
+//
+const uint32_t PLL_FILTER_LEN = 7U;
+
+float32_t PLL_FILTER_COEFFS[] = {3.196252e-02F, 1.204223e-01F, 2.176819e-01F, 2.598666e-01F, 2.176819e-01F, 1.204223e-01F, 3.196252e-02F};
+
+CAX25Demodulator::CAX25Demodulator(int8_t n) :
+m_frame(),
+m_twist(n),
+m_lpfFilter(),
+m_lpfState(),
+m_delayLine(NULL),
+m_delayPos(0U),
+m_nrziState(false),
+m_pllFilter(),
+m_pllState(),
+m_pllLast(false),
+m_pllBits(1U),
+m_pllCount(0.0F),
+m_pllJitter(0.0F),
+m_pllDCD(false),
+m_iirHistory(),
+m_hdlcOnes(0U),
+m_hdlcFlag(false),
+m_hdlcBuffer(0U),
+m_hdlcBits(0U),
+m_hdlcState(AX25_IDLE)
+{
+  m_delayLine = new bool[DELAY_LEN];
+
+  m_lpfFilter.numTaps = LPF_FILTER_LEN;
+  m_lpfFilter.pState  = m_lpfState;
+  m_lpfFilter.pCoeffs = LPF_FILTER_COEFFS;
+
+  m_pllFilter.numTaps = PLL_FILTER_LEN;
+  m_pllFilter.pState  = m_pllState;
+  m_pllFilter.pCoeffs = PLL_FILTER_COEFFS;
+
+  for (uint8_t i = 0U; i < PLL_IIR_SIZE; i++)
+    m_iirHistory[i] = 0.0F;
+}
+
+bool CAX25Demodulator::process(q15_t* samples, uint8_t length, CAX25Frame& frame)
+{
+  bool result = false;
+
+  q15_t fa[RX_BLOCK_SIZE];
+  m_twist.process(samples, fa, RX_BLOCK_SIZE);
+
+  int16_t buffer[RX_BLOCK_SIZE];
+  for (uint8_t i = 0; i < length; i++) {
+      bool   level = (fa[i] >= 0);
+      bool delayed = delay(level);
+      buffer[i] = (int16_t(level ^ delayed) << 1) - 1;
+  }
+
+  q15_t fc[RX_BLOCK_SIZE];
+  ::arm_fir_fast_q15(&m_lpfFilter, buffer, fc, RX_BLOCK_SIZE);
+
+  for (uint8_t i = 0; i < length; i++) {
+    bool bit = fc[i] >= 0;
+    bool sample = PLL(bit);
+
+    if (sample) {
+      // We will only ever get one frame because there are
+      // not enough bits in a block for more than one.
+      if (result) {
+        HDLC(NRZI(bit));
+      } else {
+        result = HDLC(NRZI(bit));
+        if (result) {
+          // Copy the frame data.
+          ::memcpy(frame.m_data, m_frame.m_data, AX25_MAX_PACKET_LEN);
+          frame.m_length = m_frame.m_length;
+          frame.m_fcs    = m_frame.m_fcs;
+          m_frame.m_length = 0U;
+        }
+      }
+    }
+  }
+
+  return result;
+}
+
+bool CAX25Demodulator::delay(bool b)
+{
+  bool r = m_delayLine[m_delayPos];
+
+  m_delayLine[m_delayPos++] = b;
+
+  if (m_delayPos >= DELAY_LEN)
+    m_delayPos = 0U;
+
+  return r;
+}
+
+bool CAX25Demodulator::NRZI(bool b)
+{
+  bool result = (b == m_nrziState);
+
+  m_nrziState = b;
+
+  return result;
+}
+
+bool CAX25Demodulator::PLL(bool input)
+{
+  bool sample = false;
+		
+  if (input != m_pllLast || m_pllBits > 16U) {
+    // Record transition.
+    m_pllLast = input;
+
+    if (m_pllCount > PLL_LIMIT)
+      m_pllCount -= SAMPLES_PER_SYMBOL;
+
+    float32_t adjust = m_pllBits > 16U ? 5.0F : 0.0F;
+    float32_t offset = m_pllCount / float32_t(m_pllBits);
+    float32_t jitter;
+    ::arm_fir_f32(&m_pllFilter, &offset, &jitter, 1U);
+
+    float32_t absOffset = adjust;
+    if (offset < 0.0F)
+      absOffset -= offset;
+    else
+      absOffset += offset;
+    m_pllJitter = iir(absOffset);
+
+    m_pllCount -= jitter / 2.0F;
+    m_pllBits = 1U;
+  } else {
+    if (m_pllCount > PLL_LIMIT) {
+      sample = true;
+      m_pllCount -= SAMPLES_PER_SYMBOL;
+      m_pllBits++;
+    }
+  }
+
+  m_pllCount += 1.0F;
+
+  return sample;
+}
+
+bool CAX25Demodulator::HDLC(bool b)
+{
+  if (m_hdlcOnes == AX25_MAX_ONES) {
+    if (b) {
+      // flag byte
+      m_hdlcFlag = true;
+    } else {
+      // bit stuffing...
+      m_hdlcFlag = false;
+      m_hdlcOnes = 0U;
+      return false;
+    }
+  }
+
+  m_hdlcBuffer >>= 1;
+  m_hdlcBuffer |= b ? 128U : 0U;
+  m_hdlcBits++;                      // Free-running until Sync byte.
+
+  if (b)
+    m_hdlcOnes++;
+  else
+    m_hdlcOnes = 0U;
+
+  if (m_hdlcFlag) {
+    bool result = false;
+
+    switch (m_hdlcBuffer) {
+      case AX25_FRAME_END:
+        if (m_frame.m_length >= AX25_MIN_FRAME_LENGTH) {
+          result = m_frame.checkCRC();
+          if (!result)
+              m_frame.m_length = 0U;
+        } else {
+            m_frame.m_length = 0U;
+        }
+        m_hdlcState = AX25_SYNC;
+        m_hdlcFlag = false;
+        m_hdlcBits = 0U;
+        break;
+
+      case AX25_FRAME_ABORT:
+        // Frame aborted
+        m_frame.m_length = 0U;
+        m_hdlcState = AX25_IDLE;
+        m_hdlcFlag = false;
+        m_hdlcBits = 0U;
+        break;
+
+      default:
+        break;
+    }
+
+    return result;
+  }
+
+  switch (m_hdlcState) {
+    case AX25_IDLE:
+      break;
+
+    case AX25_SYNC:
+      if (m_hdlcBits == 8U) {    // 8th bit.
+        // Start of frame data.
+        m_hdlcState = AX25_RECEIVE;
+        m_frame.append(m_hdlcBuffer);
+        m_hdlcBits = 0U;
+      }
+      break;
+
+    case AX25_RECEIVE:
+      if (m_hdlcBits == 8U) {    // 8th bit.
+        m_frame.append(m_hdlcBuffer);
+        m_hdlcBits = 0U;
+      }
+      break;
+
+    default:
+      break;
+  }
+
+  return false;
+}
+
+void CAX25Demodulator::setTwist(int8_t n)
+{
+  m_twist.setTwist(n);
+}
+
+bool CAX25Demodulator::isDCD()
+{
+  if (m_pllJitter <= (SAMPLES_PER_SYMBOL * 0.03F))
+    m_pllDCD = true;
+  else if (m_pllJitter >= (SAMPLES_PER_SYMBOL * 0.15F))
+    m_pllDCD = false;
+
+  return m_pllDCD;
+}
+
+float32_t CAX25Demodulator::iir(float32_t input)
+{
+  for (int8_t i = int8_t(PLL_IIR_SIZE) - 1; i != 0; i--)
+    m_iirHistory[i] = m_iirHistory[i - 1];
+
+  m_iirHistory[0] = input;
+  for (uint8_t i = 1U; i < PLL_IIR_SIZE; i++)
+    m_iirHistory[0] -= PLL_LOCK_A[i] * m_iirHistory[i];
+
+  float32_t result = 0.0F;
+  for (uint8_t i = 0U; i < PLL_IIR_SIZE; i++)
+    result += PLL_LOCK_B[i] * m_iirHistory[i];
+
+  return result;
+}
+

AX25Demodulator.h

@@ -0,0 +1,73 @@
+/*
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#if !defined(AX25Demodulator_H)
+#define  AX25Demodulator_H
+
+#include "Config.h"
+
+#include "AX25Frame.h"
+#include "AX25Twist.h"
+
+enum AX25_STATE {
+  AX25_IDLE,
+  AX25_SYNC,
+  AX25_RECEIVE
+};
+
+class CAX25Demodulator {
+public:
+  CAX25Demodulator(int8_t n);
+
+  bool process(q15_t* samples, uint8_t length, CAX25Frame& frame);
+
+  void setTwist(int8_t n);
+
+  bool isDCD();
+
+private:
+  CAX25Frame           m_frame;
+  CAX25Twist           m_twist;
+  arm_fir_instance_q15 m_lpfFilter;
+  q15_t                m_lpfState[70U];     // NoTaps + BlockSize - 1, 48 + 20 - 1 plus some spare
+  bool*                m_delayLine;
+  uint16_t             m_delayPos;
+  bool                 m_nrziState;
+  arm_fir_instance_f32 m_pllFilter;
+  float32_t            m_pllState[20U];     // NoTaps + BlockSize - 1, 7 + 1 - 1 plus some spare
+  bool                 m_pllLast;
+  uint8_t              m_pllBits;
+  float32_t            m_pllCount;
+  float32_t            m_pllJitter;
+  bool                 m_pllDCD;
+  float32_t            m_iirHistory[5U];
+  uint16_t             m_hdlcOnes;
+  bool                 m_hdlcFlag;
+  uint16_t             m_hdlcBuffer;
+  uint16_t             m_hdlcBits;
+  AX25_STATE           m_hdlcState;
+
+  bool delay(bool b);
+  bool NRZI(bool b);
+  bool PLL(bool b);
+  bool HDLC(bool b);
+  float32_t iir(float32_t input);
+};
+
+#endif
+

AX25Frame.cpp

@@ -0,0 +1,122 @@
+/*
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "Config.h"
+#include "Globals.h"
+#include "AX25Frame.h"
+
+const uint16_t CCITT_TABLE[] = {
+	0x0000,0x1189,0x2312,0x329b,0x4624,0x57ad,0x6536,0x74bf,
+	0x8c48,0x9dc1,0xaf5a,0xbed3,0xca6c,0xdbe5,0xe97e,0xf8f7,
+	0x1081,0x0108,0x3393,0x221a,0x56a5,0x472c,0x75b7,0x643e,
+	0x9cc9,0x8d40,0xbfdb,0xae52,0xdaed,0xcb64,0xf9ff,0xe876,
+	0x2102,0x308b,0x0210,0x1399,0x6726,0x76af,0x4434,0x55bd,
+	0xad4a,0xbcc3,0x8e58,0x9fd1,0xeb6e,0xfae7,0xc87c,0xd9f5,
+	0x3183,0x200a,0x1291,0x0318,0x77a7,0x662e,0x54b5,0x453c,
+	0xbdcb,0xac42,0x9ed9,0x8f50,0xfbef,0xea66,0xd8fd,0xc974,
+	0x4204,0x538d,0x6116,0x709f,0x0420,0x15a9,0x2732,0x36bb,
+	0xce4c,0xdfc5,0xed5e,0xfcd7,0x8868,0x99e1,0xab7a,0xbaf3,
+	0x5285,0x430c,0x7197,0x601e,0x14a1,0x0528,0x37b3,0x263a,
+	0xdecd,0xcf44,0xfddf,0xec56,0x98e9,0x8960,0xbbfb,0xaa72,
+	0x6306,0x728f,0x4014,0x519d,0x2522,0x34ab,0x0630,0x17b9,
+	0xef4e,0xfec7,0xcc5c,0xddd5,0xa96a,0xb8e3,0x8a78,0x9bf1,
+	0x7387,0x620e,0x5095,0x411c,0x35a3,0x242a,0x16b1,0x0738,
+	0xffcf,0xee46,0xdcdd,0xcd54,0xb9eb,0xa862,0x9af9,0x8b70,
+	0x8408,0x9581,0xa71a,0xb693,0xc22c,0xd3a5,0xe13e,0xf0b7,
+	0x0840,0x19c9,0x2b52,0x3adb,0x4e64,0x5fed,0x6d76,0x7cff,
+	0x9489,0x8500,0xb79b,0xa612,0xd2ad,0xc324,0xf1bf,0xe036,
+	0x18c1,0x0948,0x3bd3,0x2a5a,0x5ee5,0x4f6c,0x7df7,0x6c7e,
+	0xa50a,0xb483,0x8618,0x9791,0xe32e,0xf2a7,0xc03c,0xd1b5,
+	0x2942,0x38cb,0x0a50,0x1bd9,0x6f66,0x7eef,0x4c74,0x5dfd,
+	0xb58b,0xa402,0x9699,0x8710,0xf3af,0xe226,0xd0bd,0xc134,
+	0x39c3,0x284a,0x1ad1,0x0b58,0x7fe7,0x6e6e,0x5cf5,0x4d7c,
+	0xc60c,0xd785,0xe51e,0xf497,0x8028,0x91a1,0xa33a,0xb2b3,
+	0x4a44,0x5bcd,0x6956,0x78df,0x0c60,0x1de9,0x2f72,0x3efb,
+	0xd68d,0xc704,0xf59f,0xe416,0x90a9,0x8120,0xb3bb,0xa232,
+	0x5ac5,0x4b4c,0x79d7,0x685e,0x1ce1,0x0d68,0x3ff3,0x2e7a,
+	0xe70e,0xf687,0xc41c,0xd595,0xa12a,0xb0a3,0x8238,0x93b1,
+	0x6b46,0x7acf,0x4854,0x59dd,0x2d62,0x3ceb,0x0e70,0x1ff9,
+	0xf78f,0xe606,0xd49d,0xc514,0xb1ab,0xa022,0x92b9,0x8330,
+	0x7bc7,0x6a4e,0x58d5,0x495c,0x3de3,0x2c6a,0x1ef1,0x0f78 };
+
+CAX25Frame::CAX25Frame(const uint8_t* data, uint16_t length) :
+m_data(),
+m_length(0U),
+m_fcs(0U)
+{
+  for (uint16_t i = 0U; i < length && i < (AX25_MAX_PACKET_LEN - 2U); i++)
+    m_data[m_length++] = data[i];
+}
+
+CAX25Frame::CAX25Frame() :
+m_data(),
+m_length(0U),
+m_fcs(0U)
+{
+}
+
+bool CAX25Frame::append(uint16_t c)
+{
+  if (m_length == AX25_MAX_PACKET_LEN)
+    return false;
+
+  m_data[m_length++] = uint8_t(c);
+
+  return true;
+}
+
+bool CAX25Frame::checkCRC()
+{
+  union {
+    uint16_t crc16;
+    uint8_t  crc8[2U];
+  };
+
+  crc16 = 0xFFFFU;
+  for (uint16_t i = 0U; i < (m_length - 2U); i++)
+    crc16 = uint16_t(crc8[1U]) ^ CCITT_TABLE[crc8[0U] ^ m_data[i]];
+
+  crc16 = ~crc16;
+
+  if (crc8[0U] == m_data[m_length - 2U] && crc8[1U] == m_data[m_length - 1U]) {
+    m_fcs = crc16;
+    return true;
+  } else {
+    return false;
+  }
+}
+
+void CAX25Frame::addCRC()
+{
+  union {
+    uint16_t crc16;
+    uint8_t  crc8[2U];
+  };
+
+  crc16 = 0xFFFFU;
+  for (uint16_t i = 0U; i < m_length; i++)
+    crc16 = uint16_t(crc8[1U]) ^ CCITT_TABLE[crc8[0U] ^ m_data[i]];
+
+  crc16 = ~crc16;
+
+  m_fcs = crc16;
+
+  m_data[m_length++] = crc8[0U];
+  m_data[m_length++] = crc8[1U];
+}
+

AX25Frame.h

@@ -0,0 +1,43 @@
+/*
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#if !defined(AX25Frame_H)
+#define  AX25Frame_H
+
+#include "Config.h"
+
+const uint16_t AX25_MAX_PACKET_LEN = 300U;
+
+class CAX25Frame {
+public:
+  CAX25Frame(const uint8_t* data, uint16_t length);
+  CAX25Frame();
+
+  bool append(uint16_t c);
+
+  bool checkCRC();
+
+  void addCRC();
+
+  uint8_t  m_data[AX25_MAX_PACKET_LEN];
+  uint16_t m_length;
+  uint16_t m_fcs;
+};
+
+#endif
+

AX25RX.cpp

@@ -0,0 +1,205 @@
+/*
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "Config.h"
+#include "Globals.h"
+#include "AX25RX.h"
+
+/*
+ * Generated with Scipy Filter, 152 coefficients, 1100-2300Hz bandpass,
+ * Hann window, starting and ending 0 value coefficients removed.
+ *
+ * np.array(
+ *  firwin2(152,
+ *      [
+ *          0.0,
+ *          1000.0/(sample_rate/2),
+ *          1100.0/(sample_rate/2),
+ *          2350.0/(sample_rate/2),
+ *          2500.0/(sample_rate/2),
+ *          1.0
+ *      ],
+ *      [0,0,1,1,0,0],
+ *      antisymmetric = False,
+ *      window='hann') * 32768,
+ *  dtype=int)[10:-10]
+ */
+
+const uint32_t FILTER_LEN = 130U;
+
+q15_t FILTER_COEFFS[] = {
+      5,    12,    18,    21,   19,   11,    -2,   -15,   -25,   -27,
+    -21,   -11,    -3,    -5,  -19,  -43,   -69,   -83,   -73,   -35,
+     27,    98,   155,   180,  163,  109,    39,   -20,   -45,   -26,
+     23,    74,    89,    39,  -81, -247,  -407,  -501,  -480,  -334,
+    -92,   175,   388,   479,  429,  275,    99,     5,    68,   298,
+    626,   913,   994,   740,  115, -791, -1770, -2544, -2847, -2509,
+  -1527,   -76,  1518,  2875, 3653, 3653,  2875,  1518,   -76, -1527,
+  -2509, -2847, -2544, -1770, -791,  115,   740,   994,   913,   626,
+    298,    68,     5,    99,  275,  429,   479,   388,   175,   -92,
+   -334,  -480,  -501,  -407, -247,  -81,    39,    89,    74,    23,
+    -26,   -45,   -20,    39,  109,  163,   180,   155,    98,    27,
+    -35,   -73,   -83,   -69,  -43,  -19,    -5,    -3,   -11,   -21,
+    -27,   -25,   -15,    -2,   11,   19,    21,    18,    12,     5
+};
+
+CAX25RX::CAX25RX() :
+m_filter(),
+m_state(),
+m_demod1(3),
+m_demod2(6),
+m_demod3(9),
+m_lastFCS(0U),
+m_count(0U),
+m_slotTime(30U),
+m_slotCount(0U),
+m_pPersist(128U),
+m_dcd(false),
+m_canTX(false),
+m_x(1U),
+m_a(0xB7U),
+m_b(0x73U),
+m_c(0xF6U)
+{
+  m_filter.numTaps = FILTER_LEN;
+  m_filter.pState  = m_state;
+  m_filter.pCoeffs = FILTER_COEFFS;
+
+  initRand();
+}
+
+void CAX25RX::samples(q15_t* samples, uint8_t length)
+{
+  q15_t output[RX_BLOCK_SIZE];
+  ::arm_fir_fast_q15(&m_filter, samples, output, RX_BLOCK_SIZE);
+
+  m_count++;
+
+  CAX25Frame frame;
+
+  bool ret = m_demod1.process(output, length, frame);
+  if (ret) {
+    if (frame.m_fcs != m_lastFCS || m_count > 2U) {
+      m_lastFCS = frame.m_fcs;
+      m_count   = 0U;
+      serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
+    }
+    DEBUG1("Decoder 1 reported");
+  }
+
+  ret = m_demod2.process(output, length, frame);
+  if (ret) {
+    if (frame.m_fcs != m_lastFCS || m_count > 2U) {
+      m_lastFCS = frame.m_fcs;
+      m_count   = 0U;
+      serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
+    }
+    DEBUG1("Decoder 2 reported");
+  }
+
+  ret = m_demod3.process(output, length, frame);
+  if (ret) {
+    if (frame.m_fcs != m_lastFCS || m_count > 2U) {
+      m_lastFCS = frame.m_fcs;
+      m_count   = 0U;
+      serial.writeAX25Data(frame.m_data, frame.m_length - 2U);
+    }
+    DEBUG1("Decoder 3 reported");
+  }
+
+  m_slotCount += RX_BLOCK_SIZE;
+  if (m_slotCount >= m_slotTime) {
+    m_slotCount = 0U;
+
+    bool dcd1 = m_demod1.isDCD();
+    bool dcd2 = m_demod2.isDCD();
+    bool dcd3 = m_demod3.isDCD();
+    
+    if (dcd1 || dcd2 || dcd3) {
+      if (!m_dcd) {
+        io.setDecode(true);
+        io.setADCDetection(true);
+        m_dcd = true;
+      }
+
+      m_canTX = false;
+    } else {
+      if (m_dcd) {
+        io.setDecode(false);
+        io.setADCDetection(false);
+        m_dcd = false;
+      }
+
+      m_canTX = m_pPersist >= rand();
+    }
+  }
+}
+
+bool CAX25RX::canTX() const
+{
+  return m_canTX;
+}
+
+void CAX25RX::setParams(int8_t twist, uint8_t slotTime, uint8_t pPersist)
+{
+  m_demod1.setTwist(twist - 3);
+  m_demod2.setTwist(twist);
+  m_demod3.setTwist(twist + 3);
+
+  m_slotTime = slotTime * 240U;    // Slot time in samples
+  m_pPersist = pPersist;
+}
+
+// Taken from https://www.electro-tech-online.com/threads/ultra-fast-pseudorandom-number-generator-for-8-bit.124249/
+//X ABC Algorithm Random Number Generator for 8-Bit Devices:
+//This is a small PRNG, experimentally verified to have at least a 50 million byte period
+//by generating 50 million bytes and observing that there were no overapping sequences and repeats.
+//This generator passes serial correlation, entropy , Monte Carlo Pi value, arithmetic mean,
+//And many other statistical tests. This generator may have a period of up to 2^32, but this has
+//not been verified.
+//
+// By XORing 3 bytes into the a,b, and c registers, you can add in entropy from 
+//an external source easily.
+//
+//This generator is free to use, but is not suitable for cryptography due to its short period(by //cryptographic standards) and simple construction. No attempt was made to make this generator 
+// suitable for cryptographic use.
+//
+//Due to the use of a constant counter, the generator should be resistant to latching up.
+//A significant performance gain is had in that the x variable is only ever incremented.
+//
+//Only 4 bytes of ram are needed for the internal state, and generating a byte requires 3 XORs , //2 ADDs, one bit shift right , and one increment. Difficult or slow operations like multiply, etc 
+//were avoided for maximum speed on ultra low power devices.
+
+
+void CAX25RX::initRand() //Can also be used to seed the rng with more entropy during use.
+{
+  m_a = (m_a ^ m_c ^ m_x);
+  m_b = (m_b + m_a);
+  m_c = (m_c + (m_b >> 1) ^ m_a);
+}
+
+uint8_t CAX25RX::rand()
+{
+  m_x++;                           //x is incremented every round and is not affected by any other variable
+
+  m_a = (m_a ^ m_c ^ m_x);         //note the mix of addition and XOR
+  m_b = (m_b + m_a);               //And the use of very few instructions
+  m_c = (m_c + (m_b >> 1) ^ m_a);  //the right shift is to ensure that high-order bits from b can affect  
+
+  return uint8_t(m_c);             //low order bits of other variables
+}

AX25RX.h

@@ -0,0 +1,59 @@
+/*
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#if !defined(AX25RX_H)
+#define  AX25RX_H
+
+#include "Config.h"
+
+#include "AX25Demodulator.h"
+
+class CAX25RX {
+public:
+  CAX25RX();
+
+  void samples(q15_t* samples, uint8_t length);
+
+  void setParams(int8_t twist, uint8_t slotTime, uint8_t pPersist);
+
+  bool canTX() const;
+
+private:
+  arm_fir_instance_q15 m_filter;
+  q15_t                m_state[160U];    // NoTaps + BlockSize - 1, 130 + 20 - 1 plus some spare
+  CAX25Demodulator     m_demod1;
+  CAX25Demodulator     m_demod2;
+  CAX25Demodulator     m_demod3;
+  uint16_t             m_lastFCS;
+  uint32_t             m_count;
+  uint32_t             m_slotTime;
+  uint32_t             m_slotCount;
+  uint8_t              m_pPersist;
+  bool                 m_dcd;
+  bool                 m_canTX;
+  uint8_t              m_x;
+  uint8_t              m_a;
+  uint8_t              m_b;
+  uint8_t              m_c;
+  
+  void initRand();
+  uint8_t rand();
+};
+
+#endif
+

AX25TX.cpp

@@ -0,0 +1,186 @@
+/*
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "Config.h"
+#include "Globals.h"
+#include "AX25TX.h"
+
+#include "AX25Defines.h"
+#include "AX25Frame.h"
+
+
+const uint8_t START_FLAG[] = { AX25_FRAME_START };
+const uint8_t END_FLAG[]   = { AX25_FRAME_END };
+
+const uint8_t BIT_MASK_TABLE1[] = { 0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U };
+
+#define WRITE_BIT1(p,i,b) p[(i)>>3] = (b) ? (p[(i)>>3] | BIT_MASK_TABLE1[(i)&7]) : (p[(i)>>3] & ~BIT_MASK_TABLE1[(i)&7])
+#define READ_BIT1(p,i)    (p[(i)>>3] & BIT_MASK_TABLE1[(i)&7])
+
+const uint8_t BIT_MASK_TABLE2[] = { 0x01U, 0x02U, 0x04U, 0x08U, 0x10U, 0x20U, 0x40U, 0x80U };
+
+#define WRITE_BIT2(p,i,b) p[(i)>>3] = (b) ? (p[(i)>>3] | BIT_MASK_TABLE2[(i)&7]) : (p[(i)>>3] & ~BIT_MASK_TABLE2[(i)&7])
+#define READ_BIT2(p,i)    (p[(i)>>3] & BIT_MASK_TABLE2[(i)&7])
+
+const uint16_t AUDIO_TABLE_LEN = 120U;
+
+const q15_t AUDIO_TABLE_DATA[] = {
+  0, 214, 428, 641, 851, 1060, 1265, 1468, 1666, 1859, 2048, 2230, 2407, 2577, 2740, 2896, 3043, 3182, 3313, 3434, 3546, 3649,
+  3741, 3823, 3895, 3955, 4006, 4045, 4073, 4089, 4095, 4089, 4073, 4045, 4006, 3955, 3895, 3823, 3741, 3649, 3546, 3434, 3313,
+  3182, 3043, 2896, 2740, 2577, 2407, 2230, 2048, 1859, 1666, 1468, 1265, 1060, 851, 641, 428, 214, 0, -214, -428, -641, -851,
+  -1060, -1265, -1468, -1666, -1859, -2047, -2230, -2407, -2577, -2740, -2896, -3043, -3182, -3313, -3434, -3546, -3649, -3741,
+  -3823, -3895, -3955, -4006, -4045, -4073, -4089, -4095, -4089, -4073, -4045, -4006, -3955, -3895, -3823, -3741, -3649, -3546,
+  -3434, -3313, -3182, -3043, -2896, -2740, -2577, -2407, -2230, -2047, -1859, -1666, -1468, -1265, -1060, -851, -641, -428, -214
+};
+
+CAX25TX::CAX25TX() :
+m_poBuffer(),
+m_poLen(0U),
+m_poPtr(0U),
+m_txDelay(360U),
+m_tablePtr(0U),
+m_nrzi(false)
+{
+}
+
+void CAX25TX::process()
+{
+  if (m_poLen == 0U)
+    return;
+
+  if (!m_duplex) {
+    if (m_poPtr == 0U) {
+      bool tx = ax25RX.canTX();
+      if (!tx)
+        return;
+    }
+  }
+
+  uint16_t space = io.getSpace();
+
+  while (space > AX25_RADIO_SYMBOL_LENGTH) {
+    bool b = READ_BIT1(m_poBuffer, m_poPtr) != 0U;
+    m_poPtr++;
+
+    writeBit(b);
+
+    space -= AX25_RADIO_SYMBOL_LENGTH;
+
+    if (m_poPtr >= m_poLen) {
+      m_poPtr = 0U;
+      m_poLen = 0U;
+      return;
+    }
+  }
+}
+
+uint8_t CAX25TX::writeData(const uint8_t* data, uint16_t length)
+{
+  CAX25Frame frame(data, length);
+  frame.addCRC();
+
+  m_poLen    = 0U;
+  m_poPtr    = 0U;
+  m_nrzi     = false;
+  m_tablePtr = 0U;
+
+  // Add TX delay
+  for (uint16_t i = 0U; i < m_txDelay; i++, m_poLen++) {
+    bool preamble = NRZI(false);
+    WRITE_BIT1(m_poBuffer, m_poLen, preamble);
+  }
+
+  // Add the Start Flag
+  for (uint16_t i = 0U; i < 8U; i++, m_poLen++) {
+    bool b1 = READ_BIT1(START_FLAG, i) != 0U;
+    bool b2 = NRZI(b1);
+    WRITE_BIT1(m_poBuffer, m_poLen, b2);
+  }
+
+  uint8_t ones = 0U;
+  for (uint16_t i = 0U; i < (frame.m_length * 8U); i++) {
+    bool b1 = READ_BIT2(frame.m_data, i) != 0U;
+    bool b2 = NRZI(b1);
+    WRITE_BIT1(m_poBuffer, m_poLen, b2);
+    m_poLen++;
+
+    if (b1) {
+      ones++;
+      if (ones == AX25_MAX_ONES) {
+        // Bit stuffing
+        bool b = NRZI(false);
+        WRITE_BIT1(m_poBuffer, m_poLen, b);
+        m_poLen++;
+        ones = 0U;
+      }
+    } else {
+      ones = 0U;
+    }
+  }
+
+  // Add the End Flag
+  for (uint16_t i = 0U; i < 8U; i++, m_poLen++) {
+    bool b1 = READ_BIT1(END_FLAG, i) != 0U;
+    bool b2 = NRZI(b1);
+    WRITE_BIT1(m_poBuffer, m_poLen, b2);
+  }
+
+  return 0U;
+}
+
+void CAX25TX::writeBit(bool b)
+{
+  q15_t buffer[AX25_RADIO_SYMBOL_LENGTH];
+  for (uint8_t i = 0U; i < AX25_RADIO_SYMBOL_LENGTH; i++) {
+    q15_t value = AUDIO_TABLE_DATA[m_tablePtr];
+
+    if (b) {
+      // De-emphasise the lower frequency by 6dB
+      value >>= 2;
+      m_tablePtr += 6U;
+    } else {
+      m_tablePtr += 11U;
+    }
+
+    buffer[i] = value;
+
+    if (m_tablePtr >= AUDIO_TABLE_LEN)
+      m_tablePtr -= AUDIO_TABLE_LEN;
+  }
+
+  io.write(STATE_AX25, buffer, AX25_RADIO_SYMBOL_LENGTH);
+}
+
+void CAX25TX::setTXDelay(uint8_t delay)
+{
+  m_txDelay = delay * 12U;
+}
+
+uint8_t CAX25TX::getSpace() const
+{
+  return m_poLen == 0U ? 255U : 0U;
+}
+
+bool CAX25TX::NRZI(bool b)
+{
+    if (!b)
+      m_nrzi = !m_nrzi;
+
+    return m_nrzi;
+}
+

AX25TX.h

@@ -0,0 +1,49 @@
+/*
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#if !defined(AX25TX_H)
+#define  AX25TX_H
+
+#include "Config.h"
+
+class CAX25TX {
+public:
+  CAX25TX();
+
+  uint8_t writeData(const uint8_t* data, uint16_t length);
+
+  void process();
+
+  void setTXDelay(uint8_t delay);
+
+  uint8_t getSpace() const;
+
+private:
+  uint8_t    m_poBuffer[600U];
+  uint16_t   m_poLen;
+  uint16_t   m_poPtr;
+  uint16_t   m_txDelay;
+  uint16_t   m_tablePtr;
+  bool       m_nrzi;
+
+  void writeBit(bool b);
+  bool NRZI(bool b);
+};
+
+#endif
+

AX25Twist.cpp

@@ -0,0 +1,311 @@
+/*
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "Config.h"
+#include "Globals.h"
+#include "AX25Twist.h"
+
+// 1200Hz = -12dB, 2200Hz = 0dB; 3381Hz cutoff; cosine.
+q15_t dB12[] = {
+  176,
+  -812,
+  -3916,
+  -7586,
+  23536,
+  -7586,
+  -3916,
+  -812,
+  176
+};
+
+// 1200Hz = -11dB, 2200Hz = 0dB; 3258Hz cutoff; cosine.
+q15_t dB11[] = {
+  121,
+  -957,
+  -3959,
+  -7383,
+  23871,
+  -7383,
+  -3959,
+  -957,
+  121
+};
+
+// 1200Hz = -10dB, 2200Hz = 0dB; 3118Hz cutoff; cosine.
+q15_t dB10[] = {
+  56,
+  -1110,
+  -3987,
+  -7141,
+  24254,
+  -7141,
+  -3987,
+  -1110,
+  56
+};
+
+// 1200Hz = -9dB, 2200Hz = 0dB; 2959Hz cutoff; cosine.
+q15_t dB9[] = {
+  -19,
+  -1268,
+  -3994,
+  -6856,
+  24688,
+  -6856,
+  -3994,
+  -1268,
+  -19
+};
+
+// 1200Hz = -8dB, 2200Hz = 0dB; 2778Hz cutoff; cosine.
+q15_t dB8[] = {
+  -104,
+  -1424,
+  -3968,
+  -6516,
+  25182,
+  -6516,
+  -3968,
+  -1424,
+  -104
+};
+
+// 1200Hz = -7dB, 2200Hz = 0dB; 2573Hz cutoff; cosine.
+q15_t dB7[] = {
+  -196,
+  -1565,
+  -3896,
+  -6114,
+  25742,
+  -6114,
+  -3896,
+  -1565,
+  -196
+};
+
+// 1200Hz = -6dB, 2200Hz = 0dB; 2343Hz cutoff; cosine.
+q15_t dB6[] = {
+  -288,
+  -1676,
+  -3761,
+  -5642,
+  26370,
+  -5642,
+  -3761,
+  -1676,
+  -288
+};
+
+// 1200Hz = -5dB, 2200Hz = 0dB; 2085Hz cutoff; cosine.
+q15_t dB5[] = {
+  -370,
+  -1735,
+  -3545,
+  -5088,
+  27075,
+  -5088,
+  -3545,
+  -1735,
+  -370
+};
+
+// 1200Hz = -4dB, 2200Hz = 0dB; 1790Hz cutoff; cosine.
+q15_t dB4[] = {
+  -432,
+  -1715,
+  -3220,
+  -4427,
+  27880,
+  -4427,
+  -3220,
+  -1715,
+  -432
+};
+
+// 1200Hz = -3dB, 2200Hz = 0dB; 1456Hz cutoff; cosine.
+q15_t dB3[] = {
+  -452,
+  -1582,
+  -2759,
+  -3646,
+  28792,
+  -3646,
+  -2759,
+  -1582,
+  -452
+};
+
+// 1200Hz = -2dB, 2200Hz = 0dB; 1070Hz cutoff; cosine.
+q15_t dB2[] = {
+  -408,
+  -1295,
+  -2123,
+  -2710,
+  29846,
+  -2710,
+  -2123,
+  -1295,
+  -408
+};
+
+// 1200Hz = -1dB, 2200Hz = 0dB; 605Hz cutoff; cosine.
+q15_t dB1[] = {
+  -268,
+  -795,
+  -1244,
+  -1546,
+  31116,
+  -1546,
+  -1244,
+  -795,
+  -268
+};
+
+q15_t dB0[] = {
+  0,
+  0,
+  0,
+  0,
+  32767,
+  0,
+  0,
+  0,
+  0,
+};
+
+// 1200Hz = 0dB, 2200Hz = -1dB; 4130Hz cutoff; cosine.
+q15_t dB_1[] = {
+  -419,
+  -177,
+  3316,
+  8650,
+  11278,
+  8650,
+  3316,
+  -177,
+  -419
+};
+
+// 1200Hz = 0dB, 2200Hz = -2dB; 3190Hz cutoff; cosine.
+q15_t dB_2[] = {
+  -90,
+  1033,
+  3975,
+  7267,
+  8711,
+  7267,
+  3975,
+  1033,
+  -90
+};
+
+// 1200Hz = 0dB, 2200Hz = -3dB; 2330Hz cutoff; cosine.
+q15_t dB_3[] = {
+  292,
+  1680,
+  3752,
+  5615,
+  6362,
+  5615,
+  3752,
+  1680,
+  292
+};
+
+// 1200Hz = 0dB, 2200Hz = -4dB; 2657Hz cutoff; boxcar.
+q15_t dB_4[] = {
+  917,
+  3024,
+  5131,
+  6684,
+  7255,
+  6684,
+  5131,
+  3024,
+  917
+};
+
+// 1200Hz = 0dB, 2200Hz = -5dB; 2360Hz cutoff; boxcar.
+q15_t dB_5[] = {
+  1620,
+  3339,
+  4925,
+  6042,
+  6444,
+  6042,
+  4925,
+  3339,
+  1620
+};
+
+// 1200Hz = 0dB, 2200Hz = -6dB; 2067Hz cutoff; boxcar.
+q15_t dB_6[] = {
+  2161,
+  3472,
+  4605,
+  5373,
+  5644,
+  5373,
+  4605,
+  3472,
+  2161
+};
+
+q15_t* coeffs[] = {
+  dB12,
+  dB11,
+  dB10,
+  dB9,
+  dB8,
+  dB7,
+  dB6,
+  dB5,
+  dB4,
+  dB3,
+  dB2,
+  dB1,
+  dB0,
+  dB_1,
+  dB_2,
+  dB_3,
+  dB_4,
+  dB_5,
+  dB_6
+};
+
+CAX25Twist::CAX25Twist(int8_t n) :
+m_filter(),
+m_state()
+{
+  setTwist(n);
+}
+
+void CAX25Twist::process(q15_t* in, q15_t* out, uint8_t length)
+{
+  ::arm_fir_fast_q15(&m_filter, in, out, length);
+}
+
+void CAX25Twist::setTwist(int8_t n)
+{
+  uint8_t twist = uint8_t(n + 6);
+
+  m_filter.numTaps = 9;
+  m_filter.pState  = m_state;
+  m_filter.pCoeffs = coeffs[twist];
+}
+

AX25Twist.h

@@ -0,0 +1,39 @@
+/*
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#if !defined(AX25Twist_H)
+#define  AX25Twist_H
+
+#include "Config.h"
+
+
+class CAX25Twist {
+public:
+  CAX25Twist(int8_t n);
+
+  void process(q15_t* in, q15_t* out, uint8_t length);
+
+  void setTwist(int8_t n);
+
+private:
+  arm_fir_instance_q15 m_filter;
+  q15_t                m_state[40U];   // NoTaps + BlockSize - 1, 9 + 20 - 1 plus some spare
+};
+
+#endif
+

CWIdTX.cpp

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2009-2017 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2009-2017,2020 by Jonathan Naylor G4KLX
  *   Copyright (C) 2016 by Colin Durbridge G4EML
  *
  *   This program is free software; you can redistribute it and/or modify
@@ -125,7 +125,7 @@ void CCWIdTX::process()
   }
 }
 
-uint8_t CCWIdTX::write(const uint8_t* data, uint8_t length)
+uint8_t CCWIdTX::write(const uint8_t* data, uint16_t length)
 {
   ::memset(m_poBuffer, 0x00U, 1000U * sizeof(uint8_t));
 

CWIdTX.h

@@ -1,6 +1,6 @@
 /*
  *   Copyright (C) 2009-2015 by Jonathan Naylor G4KLX
- *   Copyright (C) 2016 by Colin Durbridge G4EML
+ *   Copyright (C) 2016,2020 by Colin Durbridge G4EML
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -28,7 +28,7 @@ public:
 
   void process();
 
-  uint8_t write(const uint8_t* data, uint8_t length);
+  uint8_t write(const uint8_t* data, uint16_t length);
 
   void reset();
 

CalDMR.cpp

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2009-2015 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2009-2015,2020 by Jonathan Naylor G4KLX
  *   Copyright (C) 2016 by Colin Durbridge G4EML
  *
  *   This program is free software; you can redistribute it and/or modify
@@ -208,7 +208,7 @@ void CCalDMR::dmrdmo1k()
   }
 }
 
-uint8_t CCalDMR::write(const uint8_t* data, uint8_t length)
+uint8_t CCalDMR::write(const uint8_t* data, uint16_t length)
 {
   if (length != 1U)
     return 4U;

CalDMR.h

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2009-2015 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2009-2015,2020 by Jonathan Naylor G4KLX
  *   Copyright (C) 2016 by Colin Durbridge G4EML
  *
  *   This program is free software; you can redistribute it and/or modify
@@ -41,7 +41,7 @@ public:
   void createData1k(uint8_t n);
   void createDataDMO1k(uint8_t n);
 
-  uint8_t write(const uint8_t* data, uint8_t length);
+  uint8_t write(const uint8_t* data, uint16_t length);
 
 private:
   bool      m_transmit;

CalDStarTX.cpp

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2009-2016 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2009-2016,2020 by Jonathan Naylor G4KLX
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -162,7 +162,7 @@ void CCalDStarTX::process()
   m_count = (m_count + 1U) % (30U * 21U);
 }
 
-uint8_t CCalDStarTX::write(const uint8_t* data, uint8_t length)
+uint8_t CCalDStarTX::write(const uint8_t* data, uint16_t length)
 {
   if (length != 1U)
     return 4U;

CalDStarTX.h

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016,2020 by Jonathan Naylor G4KLX
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -26,7 +26,7 @@ class CCalDStarTX {
 public:
   CCalDStarTX();
 
-  uint8_t write(const uint8_t* data, uint8_t length);
+  uint8_t write(const uint8_t* data, uint16_t length);
 
   void process();
 

CalFM.cpp

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2009-2015 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2009-2015,2020 by Jonathan Naylor G4KLX
  *   Copyright (C) 2016 by Colin Durbridge G4EML
  *   Copyright (C) 2020 by Phil Taylor M0VSE
  *
@@ -116,7 +116,7 @@ void CCalFM::process()
 }
 
 
-uint8_t CCalFM::write(const uint8_t* data, uint8_t length)
+uint8_t CCalFM::write(const uint8_t* data, uint16_t length)
 {
   if (length != 1U)
     return 4U;

CalFM.h

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2009-2015 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2009-2015,2020 by Jonathan Naylor G4KLX
  *   Copyright (C) 2016 by Colin Durbridge G4EML
  *   Copyright (C) 2020 by Phil Taylor M0VSE
  *
@@ -35,7 +35,7 @@ public:
   void fm25kcal();
   void fm30kcal();
 
-  uint8_t write(const uint8_t* data, uint8_t length);
+  uint8_t write(const uint8_t* data, uint16_t length);
 
 private:
   uint16_t  m_frequency;

CalNXDN.cpp

@@ -1,5 +1,6 @@
 /*
  *   Copyright (C) 2018 by Andy Uribe CA6JAU
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -79,7 +80,7 @@ void CCalNXDN::process()
   }
 }
 
-uint8_t CCalNXDN::write(const uint8_t* data, uint8_t length)
+uint8_t CCalNXDN::write(const uint8_t* data, uint16_t length)
 {
   if (length != 1U)
     return 4U;

CalNXDN.h

@@ -1,5 +1,6 @@
 /*
  *   Copyright (C) 2018 by Andy Uribe CA6JAU
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -32,7 +33,7 @@ public:
 
   void process();
 
-  uint8_t write(const uint8_t* data, uint8_t length);
+  uint8_t write(const uint8_t* data, uint16_t length);
 
 private:
   bool      m_transmit;

CalP25.cpp

@@ -1,5 +1,6 @@
 /*
  *   Copyright (C) 2018 by Andy Uribe CA6JAU
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -82,7 +83,7 @@ void CCalP25::process()
   }
 }
 
-uint8_t CCalP25::write(const uint8_t* data, uint8_t length)
+uint8_t CCalP25::write(const uint8_t* data, uint16_t length)
 {
   if (length != 1U)
     return 4U;

CalP25.h

@@ -1,5 +1,6 @@
 /*
  *   Copyright (C) 2018 by Andy Uribe CA6JAU
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -34,7 +35,7 @@ public:
 
   void process();
 
-  uint8_t write(const uint8_t* data, uint8_t length);
+  uint8_t write(const uint8_t* data, uint16_t length);
 
 private:
   bool      m_transmit;

CalPOCSAG.cpp

@@ -1,5 +1,6 @@
 /*
  *   Copyright (C) 2019 by Florian Wolters DF2ET
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -38,7 +39,7 @@ void CCalPOCSAG::process()
   pocsagTX.writeByte(0xAAU);
 }
 
-uint8_t CCalPOCSAG::write(const uint8_t* data, uint8_t length)
+uint8_t CCalPOCSAG::write(const uint8_t* data, uint16_t length)
 {
   if (length != 1U)
     return 4U;

CalPOCSAG.h

@@ -1,5 +1,6 @@
 /*
  *   Copyright (C) 2019 by Florian Wolters DF2ET
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -32,7 +33,7 @@ public:
 
   void process();
 
-  uint8_t write(const uint8_t* data, uint8_t length);
+  uint8_t write(const uint8_t* data, uint16_t length);
 
 private:
   POCSAGCAL m_state;

Config.h

@@ -44,7 +44,7 @@
 // #define USE_COS_AS_LOCKOUT
 
 // Use pins to output the current mode via LEDs
-// #define MODE_LEDS
+#define MODE_LEDS
 
 // For the original Arduino Due pin layout
 // #define ARDUINO_DUE_PAPA
@@ -93,3 +93,4 @@
 #define USE_ALTERNATE_FM_LEDS
 
 #endif
+

DMRDMOTX.cpp

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2009-2017 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2009-2017,2020 by Jonathan Naylor G4KLX
  *   Copyright (C) 2016 by Colin Durbridge G4EML
  *   Copyright (C) 2017 by Andy Uribe CA6JAU
  *
@@ -104,7 +104,7 @@ void CDMRDMOTX::process()
   }
 }
 
-uint8_t CDMRDMOTX::writeData(const uint8_t* data, uint8_t length)
+uint8_t CDMRDMOTX::writeData(const uint8_t* data, uint16_t length)
 {
   if (length != (DMR_FRAME_LENGTH_BYTES + 1U))
     return 4U;

DMRDMOTX.h

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016,2017 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016,2017,2020 by Jonathan Naylor G4KLX
  *   Copyright (C) 2016 by Colin Durbridge G4EML
  *
  *   This program is free software; you can redistribute it and/or modify
@@ -29,7 +29,7 @@ class CDMRDMOTX {
 public:
   CDMRDMOTX();
 
-  uint8_t writeData(const uint8_t* data, uint8_t length);
+  uint8_t writeData(const uint8_t* data, uint16_t length);
 
   void process();
 

DMRTX.cpp

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2009-2017 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2009-2017,2020 by Jonathan Naylor G4KLX
  *   Copyright (C) 2016 by Colin Durbridge G4EML
  *   Copyright (C) 2017 by Andy Uribe CA6JAU
  *
@@ -144,7 +144,7 @@ void CDMRTX::process()
   }
 }
 
-uint8_t CDMRTX::writeData1(const uint8_t* data, uint8_t length)
+uint8_t CDMRTX::writeData1(const uint8_t* data, uint16_t length)
 {
   if (length != (DMR_FRAME_LENGTH_BYTES + 1U))
     return 4U;
@@ -168,7 +168,7 @@ uint8_t CDMRTX::writeData1(const uint8_t* data, uint8_t length)
   return 0U;
 }
 
-uint8_t CDMRTX::writeData2(const uint8_t* data, uint8_t length)
+uint8_t CDMRTX::writeData2(const uint8_t* data, uint16_t length)
 {
   if (length != (DMR_FRAME_LENGTH_BYTES + 1U))
     return 4U;
@@ -192,7 +192,7 @@ uint8_t CDMRTX::writeData2(const uint8_t* data, uint8_t length)
   return 0U;
 }
 
-uint8_t CDMRTX::writeShortLC(const uint8_t* data, uint8_t length)
+uint8_t CDMRTX::writeShortLC(const uint8_t* data, uint16_t length)
 {
   if (length != 9U)
     return 4U;
@@ -208,7 +208,7 @@ uint8_t CDMRTX::writeShortLC(const uint8_t* data, uint8_t length)
   return 0U;
 }
 
-uint8_t CDMRTX::writeAbort(const uint8_t* data, uint8_t length)
+uint8_t CDMRTX::writeAbort(const uint8_t* data, uint16_t length)
 {
   if (length != 1U)
     return 4U;

DMRTX.h

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016,2017 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016,2017,2020 by Jonathan Naylor G4KLX
  *   Copyright (C) 2016 by Colin Durbridge G4EML
  *
  *   This program is free software; you can redistribute it and/or modify
@@ -38,11 +38,11 @@ class CDMRTX {
 public:
   CDMRTX();
 
-  uint8_t writeData1(const uint8_t* data, uint8_t length);
-  uint8_t writeData2(const uint8_t* data, uint8_t length);
+  uint8_t writeData1(const uint8_t* data, uint16_t length);
+  uint8_t writeData2(const uint8_t* data, uint16_t length);
 
-  uint8_t writeShortLC(const uint8_t* data, uint8_t length);
-  uint8_t writeAbort(const uint8_t* data, uint8_t length);
+  uint8_t writeShortLC(const uint8_t* data, uint16_t length);
+  uint8_t writeAbort(const uint8_t* data, uint16_t length);
 
   void setStart(bool start);
   void setCal(bool start);

DStarTX.cpp

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2009-2017 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2009-2017,2020 by Jonathan Naylor G4KLX
  *   Copyright (C) 2017 by Andy Uribe CA6JAU
  *
  *   This program is free software; you can redistribute it and/or modify
@@ -280,7 +280,7 @@ void CDStarTX::process()
   }
 }
 
-uint8_t CDStarTX::writeHeader(const uint8_t* header, uint8_t length)
+uint8_t CDStarTX::writeHeader(const uint8_t* header, uint16_t length)
 {
   if (length != DSTAR_HEADER_LENGTH_BYTES)
     return 4U;
@@ -299,7 +299,7 @@ uint8_t CDStarTX::writeHeader(const uint8_t* header, uint8_t length)
   return 0U;
 }
 
-uint8_t CDStarTX::writeData(const uint8_t* data, uint8_t length)
+uint8_t CDStarTX::writeData(const uint8_t* data, uint16_t length)
 {
   if (length != DSTAR_DATA_LENGTH_BYTES)
     return 4U;

DStarTX.h

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016,2017 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016,2017,2020 by Jonathan Naylor G4KLX
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -27,8 +27,8 @@ class CDStarTX {
 public:
   CDStarTX();
 
-  uint8_t writeHeader(const uint8_t* header, uint8_t length);
-  uint8_t writeData(const uint8_t* data, uint8_t length);
+  uint8_t writeHeader(const uint8_t* header, uint16_t length);
+  uint8_t writeData(const uint8_t* data, uint16_t length);
   uint8_t writeEOT();
 
   void process();

FM.cpp

@@ -20,18 +20,26 @@
 #include "Globals.h"
 #include "FM.h"
 
-
 const uint16_t FM_TX_BLOCK_SIZE = 100U;
 const uint16_t FM_SERIAL_BLOCK_SIZE = 84U;//this is the number of sample pairs to send over serial. One sample pair is 3bytes.
                                           //three times this value shall never exceed 252
 const uint16_t FM_SERIAL_BLOCK_SIZE_BYTES = FM_SERIAL_BLOCK_SIZE * 3U;
 
+/*
+ * Access Mode values are:
+ *   0 - Carrier access with COS
+ *   1 - CTCSS only access without COS
+ *   2 - CTCSS only access with COS
+ *   3 - CTCSS only access with COS to start, then carrier access with COS
+ */
+
 CFM::CFM() :
 m_callsign(),
 m_rfAck(),
 m_extAck(),
 m_ctcssRX(),
 m_ctcssTX(),
+m_squelch(),
 m_timeoutTone(),
 m_state(FS_LISTENING),
 m_callsignAtStart(false),
@@ -41,20 +49,22 @@ m_callsignTimer(),
 m_timeoutTimer(),
 m_holdoffTimer(),
 m_kerchunkTimer(),
-m_kerchunkTX(true),
 m_ackMinTimer(),
 m_ackDelayTimer(),
 m_hangTimer(),
 m_statusTimer(),
+m_reverseTimer(),
+m_needReverse(false),
 m_filterStage1(  724,   1448,   724, 32768, -37895, 21352),//3rd order Cheby Filter 300 to 2700Hz, 0.2dB passband ripple, sampling rate 24kHz
 m_filterStage2(32768,      0,-32768, 32768, -50339, 19052),
 m_filterStage3(32768, -65536, 32768, 32768, -64075, 31460),
 m_blanking(),
-m_useCOS(true),
+m_accessMode(1U),
 m_cosInvert(false),
+m_noiseSquelch(false),
 m_rfAudioBoost(1U),
 m_extAudioBoost(1U),
-m_downsampler(400U),// 100 ms of audio
+m_downSampler(400U),// 100 ms of audio
 m_extEnabled(false),
 m_rxLevel(1),
 m_inputRFRB(2401U),   // 100ms of audio + 1 sample
@@ -62,18 +72,15 @@ m_outputRFRB(2400U),  // 100ms of audio
 m_inputExtRB()
 {
   m_statusTimer.setTimeout(1U, 0U);
+  m_reverseTimer.setTimeout(0U, 150U);
 
   insertDelay(100U);
 }
 
 void CFM::samples(bool cos, q15_t* samples, uint8_t length)
 {
-  if (m_useCOS) {
-    if (m_cosInvert)
-      cos = !cos;
-  } else {
-    cos = true;
-  }
+  if (m_cosInvert)
+    cos = !cos;
 
   clock(length);
 
@@ -81,34 +88,82 @@ void CFM::samples(bool cos, q15_t* samples, uint8_t length)
   for (; i < length; i++) {
     // ARMv7-M has hardware integer division 
     q15_t currentRFSample = q15_t((q31_t(samples[i]) << 8) / m_rxLevel);
-    uint8_t ctcssState = m_ctcssRX.process(currentRFSample);
 
-    if (!m_useCOS) {
-      // Delay the audio by 100ms to better match the CTCSS detector output
-      m_inputRFRB.put(currentRFSample);
-      m_inputRFRB.get(currentRFSample);
-    }
+    if (m_noiseSquelch)
+      cos = m_squelch.process(currentRFSample);
 
     q15_t currentExtSample;
     bool inputExt = m_inputExtRB.getSample(currentExtSample);//always consume the external input data so it does not overflow
     inputExt = inputExt && m_extEnabled;
 
-    if (!inputExt && (CTCSS_NOT_READY(ctcssState)) && m_modemState != STATE_FM) {
-      //Not enough samples to determine if you have CTCSS, just carry on. But only if we haven't any external data in the queue
-      continue;
-    } else if ((inputExt || CTCSS_READY(ctcssState)) && m_modemState != STATE_FM) {
-      //we had enough samples for CTCSS and we are in some other mode than FM
-      bool validCTCSS = CTCSS_VALID(ctcssState);
-      stateMachine(validCTCSS && cos, inputExt);
-      if (m_modemState != STATE_FM)
-        continue;
-    } else if ((inputExt || CTCSS_NOT_READY(ctcssState)) && m_modemState == STATE_FM && i == length - 1) {
-      //Not enough samples for CTCSS but we already are in FM, trigger the state machine
-      //but do not trigger the state machine on every single sample, save CPU!
-      bool validCTCSS = CTCSS_VALID(ctcssState);
-      stateMachine(validCTCSS && cos, inputExt);
+    switch (m_accessMode) {
+      case 0U:
+        if (!inputExt && !cos && m_modemState != STATE_FM)
+          continue;
+        else
+          stateMachine(cos, inputExt);
+        break;
+
+      case 1U: {
+          bool ctcss = m_ctcssRX.process(currentRFSample);
+
+          // Delay the audio by 100ms to better match the CTCSS detector output
+          m_inputRFRB.put(currentRFSample);
+          m_inputRFRB.get(currentRFSample);
+
+          if (!inputExt && !ctcss && m_modemState != STATE_FM) {
+            // No CTCSS detected, just carry on
+            continue;
+          } else if ((inputExt || ctcss) && m_modemState != STATE_FM) {
+            // We had CTCSS or external input
+            stateMachine(ctcss, inputExt);
+            if (m_state == FS_LISTENING)
+              continue;
+          } else {
+            stateMachine(ctcss, inputExt);
+          }
+        }
+        break;
+
+      case 2U: {
+          bool ctcss = m_ctcssRX.process(currentRFSample);
+          if (!inputExt && !ctcss && m_modemState != STATE_FM) {
+            // No CTCSS detected, just carry on
+            continue;
+          } else if ((inputExt || (ctcss && cos)) && m_modemState != STATE_FM) {
+            // We had CTCSS or external input
+            stateMachine(ctcss && cos, inputExt);
+            if (m_state == FS_LISTENING)
+              continue;
+          } else {
+            stateMachine(ctcss && cos, inputExt);
+          }
+        }
+        break;
+
+      default: {
+          bool ctcss = m_ctcssRX.process(currentRFSample);
+          if (!inputExt && !ctcss && m_modemState != STATE_FM) {
+            // No CTCSS detected, just carry on
+            continue;
+          } else if ((inputExt || (ctcss && cos)) && m_modemState != STATE_FM) {
+            // We had CTCSS or external input
+            stateMachine(ctcss && cos, inputExt);
+            if (m_state == FS_LISTENING)
+              continue;
+          } else {
+            stateMachine(cos, inputExt);
+          }
+        }
+        break;
     }
 
+    if (m_modemState != STATE_FM)
+      continue;
+
+    if (m_state == FS_LISTENING && !m_rfAck.isWanted() && !m_extAck.isWanted() && !m_callsign.isWanted() && !m_reverseTimer.isRunning())
+      continue;
+
     q15_t currentSample = currentRFSample;
     q15_t currentBoost  = m_rfAudioBoost;
     if (m_state == FS_RELAYING_EXT || m_state == FS_KERCHUNK_EXT) {
@@ -117,14 +172,24 @@ void CFM::samples(bool cos, q15_t* samples, uint8_t length)
     }
 
     // Only let RF audio through when relaying RF audio
-    if (m_state == FS_RELAYING_RF || m_state == FS_KERCHUNK_RF || m_state == FS_RELAYING_EXT || m_state == FS_KERCHUNK_EXT) {
-      currentSample = m_blanking.process(currentSample);
-      if (m_extEnabled && (m_state == FS_RELAYING_RF || m_state == FS_KERCHUNK_RF))
-        m_downsampler.addSample(currentSample);
+    if (m_duplex) {
+      if (m_state == FS_RELAYING_RF || m_state == FS_KERCHUNK_RF || m_state == FS_RELAYING_EXT || m_state == FS_KERCHUNK_EXT) {
+        currentSample = m_blanking.process(currentSample);
+        if (m_extEnabled && (m_state == FS_RELAYING_RF || m_state == FS_KERCHUNK_RF))
+          m_downSampler.addSample(currentSample);
 
-      currentSample *= currentBoost;
+        currentSample *= currentBoost;
+      } else {
+        currentSample = 0;
+      }
     } else {
-      currentSample = 0;
+        if (m_state == FS_RELAYING_EXT || m_state == FS_KERCHUNK_EXT) {
+          currentSample *= currentBoost;
+        } else {
+          if (m_extEnabled && (m_state == FS_RELAYING_RF || m_state == FS_KERCHUNK_RF))
+            m_downSampler.addSample(currentSample);
+          continue; 
+        }
     }
 
     if (!m_callsign.isRunning() && !m_extAck.isRunning())
@@ -140,12 +205,12 @@ void CFM::samples(bool cos, q15_t* samples, uint8_t length)
         currentSample += m_callsign.getLowAudio();
     }
 
+    currentSample = m_filterStage3.filter(m_filterStage2.filter(m_filterStage1.filter(currentSample)));
+
     if (!m_callsign.isRunning() && !m_rfAck.isRunning() && !m_extAck.isRunning())
       currentSample += m_timeoutTone.getAudio();
 
-    currentSample = m_filterStage3.filter(m_filterStage2.filter(m_filterStage1.filter(currentSample)));
-
-    currentSample += m_ctcssTX.getAudio();
+    currentSample += m_ctcssTX.getAudio(m_reverseTimer.isRunning());
 
     m_outputRFRB.put(currentSample);
   }
@@ -177,7 +242,7 @@ void CFM::process()
   }
 
   if (m_extEnabled) {
-    uint16_t length = m_downsampler.getData();
+    uint16_t length = m_downSampler.getData();
 
     if (length >= FM_SERIAL_BLOCK_SIZE) {
       if (length > FM_SERIAL_BLOCK_SIZE)
@@ -186,7 +251,7 @@ void CFM::process()
       TSamplePairPack serialSamples[FM_SERIAL_BLOCK_SIZE];
 
       for (uint16_t j = 0U; j < length; j++)
-        m_downsampler.getPackedData(serialSamples[j]);
+        m_downSampler.getPackedData(serialSamples[j]);
 
       serial.writeFMData((uint8_t*)serialSamples, length * sizeof(TSamplePairPack));
     }
@@ -204,6 +269,7 @@ void CFM::reset()
   m_ackDelayTimer.stop();
   m_hangTimer.stop();
   m_statusTimer.stop();
+  m_reverseTimer.stop();
 
   m_ctcssRX.reset();
   m_rfAck.stop();
@@ -214,7 +280,10 @@ void CFM::reset()
   m_outputRFRB.reset();
   m_inputExtRB.reset();
 
-  m_downsampler.reset();
+  m_downSampler.reset();
+  m_squelch.reset();
+  
+  m_needReverse = false;
 }
 
 uint8_t CFM::setCallsign(const char* callsign, uint8_t speed, uint16_t frequency, uint8_t time, uint8_t holdoff, uint8_t highLevel, uint8_t lowLevel, bool callsignAtStart, bool callsignAtEnd, bool callsignAtLatch)
@@ -245,17 +314,17 @@ uint8_t CFM::setAck(const char* rfAck, uint8_t speed, uint16_t frequency, uint8_
   return m_rfAck.setParams(rfAck, speed, frequency, level, level);
 }
 
-uint8_t CFM::setMisc(uint16_t timeout, uint8_t timeoutLevel, uint8_t ctcssFrequency, uint8_t ctcssHighThreshold, uint8_t ctcssLowThreshold, uint8_t ctcssLevel, uint8_t kerchunkTime, bool kerchunkTX, uint8_t hangTime, bool useCOS, bool cosInvert, uint8_t rfAudioBoost, uint8_t maxDev, uint8_t rxLevel)
+uint8_t CFM::setMisc(uint16_t timeout, uint8_t timeoutLevel, uint8_t ctcssFrequency, uint8_t ctcssHighThreshold, uint8_t ctcssLowThreshold, uint8_t ctcssLevel, uint8_t kerchunkTime, uint8_t hangTime, uint8_t accessMode, bool cosInvert, bool noiseSquelch, uint8_t squelchHighThreshold, uint8_t squelchLowThreshold, uint8_t rfAudioBoost, uint8_t maxDev, uint8_t rxLevel)
 {
-  m_useCOS    = useCOS;
-  m_cosInvert = cosInvert;
+  m_accessMode   = accessMode;
+  m_cosInvert    = cosInvert;
+  m_noiseSquelch = noiseSquelch;
 
   m_rfAudioBoost = q15_t(rfAudioBoost);
 
   m_timeoutTimer.setTimeout(timeout, 0U);
 
   m_kerchunkTimer.setTimeout(kerchunkTime, 0U);
-  m_kerchunkTX = kerchunkTX;
 
   m_hangTimer.setTimeout(hangTime, 0U);
 
@@ -264,6 +333,8 @@ uint8_t CFM::setMisc(uint16_t timeout, uint8_t timeoutLevel, uint8_t ctcssFreque
 
   m_rxLevel = rxLevel; //q15_t(255)/q15_t(rxLevel >> 1);
 
+  m_squelch.setParams(squelchHighThreshold, squelchLowThreshold);
+
   uint8_t ret = m_ctcssRX.setParams(ctcssFrequency, ctcssHighThreshold, ctcssLowThreshold);
   if (ret != 0U)
     return ret;
@@ -281,51 +352,109 @@ uint8_t CFM::setExt(const char* ack, uint8_t audioBoost, uint8_t speed, uint16_t
 }
 
 void CFM::stateMachine(bool validRFSignal, bool validExtSignal)
+{
+  if (m_duplex)
+    duplexStateMachine(validRFSignal, validExtSignal);
+  else
+    simplexStateMachine(validRFSignal, validExtSignal);
+}
+
+void CFM::simplexStateMachine(bool validRFSignal, bool validExtSignal)
 {
   switch (m_state) {
     case FS_LISTENING:
-      listeningState(validRFSignal, validExtSignal);
-      break;
-    case FS_KERCHUNK_RF:
-      kerchunkRFState(validRFSignal);
+      listeningStateSimplex(validRFSignal, validExtSignal);
       break;
     case FS_RELAYING_RF:
-      relayingRFState(validRFSignal);
+      relayingRFStateSimplex(validRFSignal);
       break;
     case FS_RELAYING_WAIT_RF:
-      relayingRFWaitState(validRFSignal);
+      relayingRFWaitStateSimplex(validRFSignal);
       break;
     case FS_TIMEOUT_RF:
-      timeoutRFState(validRFSignal);
+      timeoutRFStateSimplex(validRFSignal);
       break;
     case FS_TIMEOUT_WAIT_RF:
-      timeoutRFWaitState(validRFSignal);
-      break;
-    case FS_KERCHUNK_EXT:
-      kerchunkExtState(validExtSignal);
+      timeoutRFStateSimplex(validRFSignal);
       break;
     case FS_RELAYING_EXT:
-      relayingExtState(validExtSignal);
+      relayingExtStateSimplex(validExtSignal);
       break;
     case FS_RELAYING_WAIT_EXT:
-      relayingExtWaitState(validExtSignal);
+      relayingExtWaitStateSimplex(validExtSignal);
       break;
     case FS_TIMEOUT_EXT:
-      timeoutExtState(validExtSignal);
+      timeoutExtStateSimplex(validExtSignal);
       break;
     case FS_TIMEOUT_WAIT_EXT:
-      timeoutExtWaitState(validExtSignal);
+      timeoutExtWaitStateSimplex(validExtSignal);
+      break;
+    default:
+      break;
+  }
+
+  if (m_state == FS_LISTENING) {
+    if (!m_reverseTimer.isRunning() && m_needReverse)
+      m_reverseTimer.start();
+
+    if (m_reverseTimer.isRunning() && m_reverseTimer.hasExpired()) {
+      m_reverseTimer.stop();
+      m_needReverse = false;
+    }
+  }
+}
+
+void CFM::duplexStateMachine(bool validRFSignal, bool validExtSignal)
+{
+  switch (m_state) {
+    case FS_LISTENING:
+      listeningStateDuplex(validRFSignal, validExtSignal);
+      break;
+    case FS_KERCHUNK_RF:
+      kerchunkRFStateDuplex(validRFSignal);
+      break;
+    case FS_RELAYING_RF:
+      relayingRFStateDuplex(validRFSignal);
+      break;
+    case FS_RELAYING_WAIT_RF:
+      relayingRFWaitStateDuplex(validRFSignal);
+      break;
+    case FS_TIMEOUT_RF:
+      timeoutRFStateDuplex(validRFSignal);
+      break;
+    case FS_TIMEOUT_WAIT_RF:
+      timeoutRFWaitStateDuplex(validRFSignal);
+      break;
+    case FS_KERCHUNK_EXT:
+      kerchunkExtStateDuplex(validExtSignal);
+      break;
+    case FS_RELAYING_EXT:
+      relayingExtStateDuplex(validExtSignal);
+      break;
+    case FS_RELAYING_WAIT_EXT:
+      relayingExtWaitStateDuplex(validExtSignal);
+      break;
+    case FS_TIMEOUT_EXT:
+      timeoutExtStateDuplex(validExtSignal);
+      break;
+    case FS_TIMEOUT_WAIT_EXT:
+      timeoutExtWaitStateDuplex(validExtSignal);
       break;
     case FS_HANG:
-      hangState(validRFSignal, validExtSignal);
+      hangStateDuplex(validRFSignal, validExtSignal);
       break;
     default:
       break;
   }
 
   if (m_state == FS_LISTENING && !m_rfAck.isWanted() && !m_extAck.isWanted() && !m_callsign.isWanted()) {
-    m_outputRFRB.reset();
-    m_downsampler.reset();
+    if (!m_reverseTimer.isRunning() && m_needReverse)
+      m_reverseTimer.start();
+
+    if (m_reverseTimer.isRunning() && m_reverseTimer.hasExpired()) {
+      m_reverseTimer.stop();
+      m_needReverse = false;
+    }
   }
 }
 
@@ -339,6 +468,7 @@ void CFM::clock(uint8_t length)
   m_ackDelayTimer.clock(length);
   m_hangTimer.clock(length);
   m_statusTimer.clock(length);
+  m_reverseTimer.clock(length);
 
   if (m_statusTimer.isRunning() && m_statusTimer.hasExpired()) {
     serial.writeFMStatus(m_state);
@@ -346,7 +476,7 @@ void CFM::clock(uint8_t length)
   }
 }
 
-void CFM::listeningState(bool validRFSignal, bool validExtSignal)
+void CFM::listeningStateDuplex(bool validRFSignal, bool validExtSignal)
 {
   if (validRFSignal) {
     if (m_kerchunkTimer.getTimeout() > 0U) {
@@ -362,12 +492,13 @@ void CFM::listeningState(bool validRFSignal, bool validExtSignal)
         sendCallsign();
     }
 
-    if (m_state == FS_RELAYING_RF || (m_state == FS_KERCHUNK_RF && m_kerchunkTX)) {
+    if (m_state == FS_RELAYING_RF || m_state == FS_KERCHUNK_RF) {
       insertSilence(50U);
 
       beginRelaying();
 
       m_callsignTimer.start();
+      m_reverseTimer.stop();
 
       io.setDecode(true);
       io.setADCDetection(true);
@@ -389,12 +520,13 @@ void CFM::listeningState(bool validRFSignal, bool validExtSignal)
         sendCallsign();
     }
 
-    if (m_state == FS_RELAYING_EXT || (m_state == FS_KERCHUNK_EXT && m_kerchunkTX)) {
+    if (m_state == FS_RELAYING_EXT || m_state == FS_KERCHUNK_EXT) {
       insertSilence(50U);
 
       beginRelaying();
 
       m_callsignTimer.start();
+      m_reverseTimer.stop();
 
       m_statusTimer.start();
       serial.writeFMStatus(m_state);
@@ -402,26 +534,41 @@ void CFM::listeningState(bool validRFSignal, bool validExtSignal)
   }
 }
 
-void CFM::kerchunkRFState(bool validSignal)
+void CFM::listeningStateSimplex(bool validRFSignal, bool validExtSignal)
+{
+  if (validRFSignal) {
+    DEBUG1("State to RELAYING_RF");
+    m_state = FS_RELAYING_RF;
+
+    io.setDecode(true);
+    io.setADCDetection(true);
+
+    m_timeoutTimer.start();
+    m_reverseTimer.stop();
+
+    m_statusTimer.start();
+    serial.writeFMStatus(m_state);
+  } else if (validExtSignal) {
+    DEBUG1("State to RELAYING_EXT");
+    m_state = FS_RELAYING_EXT;
+
+    insertSilence(50U);
+
+    m_timeoutTimer.start();
+    m_reverseTimer.stop();
+
+    m_statusTimer.start();
+    serial.writeFMStatus(m_state);
+  }
+}
+
+void CFM::kerchunkRFStateDuplex(bool validSignal)
 {
   if (validSignal) {
     if (m_kerchunkTimer.hasExpired()) {
       DEBUG1("State to RELAYING_RF");
       m_state = FS_RELAYING_RF;
       m_kerchunkTimer.stop();
-      if (!m_kerchunkTX) {
-        insertSilence(50U);
-
-        beginRelaying();
-
-        m_callsignTimer.start();
-
-        io.setDecode(true);
-        io.setADCDetection(true);
-
-        m_statusTimer.start();
-        serial.writeFMStatus(m_state);
-      }
       if (m_callsignAtStart && m_callsignAtLatch) {
         sendCallsign();
         m_callsignTimer.start();
@@ -438,13 +585,13 @@ void CFM::kerchunkRFState(bool validSignal)
     m_ackMinTimer.stop();
     m_callsignTimer.stop();
     m_statusTimer.stop();
-
+    m_needReverse = true;
     if (m_extEnabled)
       serial.writeFMEOT();
   }
 }
 
-void CFM::relayingRFState(bool validSignal)
+void CFM::relayingRFStateDuplex(bool validSignal)
 {
   if (validSignal) {
     if (m_timeoutTimer.isRunning() && m_timeoutTimer.hasExpired()) {
@@ -475,7 +622,32 @@ void CFM::relayingRFState(bool validSignal)
   }
 }
 
-void CFM::relayingRFWaitState(bool validSignal)
+void CFM::relayingRFStateSimplex(bool validSignal)
+{
+  if (validSignal) {
+    if (m_timeoutTimer.isRunning() && m_timeoutTimer.hasExpired()) {
+      DEBUG1("State to TIMEOUT_RF");
+      m_state = FS_TIMEOUT_RF;
+
+      m_timeoutTimer.stop();
+
+      if (m_extEnabled)
+        serial.writeFMEOT();
+    }
+  } else {
+    io.setDecode(false);
+    io.setADCDetection(false);
+
+    DEBUG1("State to RELAYING_WAIT_RF");
+    m_state = FS_RELAYING_WAIT_RF;
+    m_ackDelayTimer.start();
+
+    if (m_extEnabled)
+      serial.writeFMEOT();
+  }
+}
+
+void CFM::relayingRFWaitStateDuplex(bool validSignal)
 {
   if (validSignal) {
     io.setDecode(true);
@@ -513,23 +685,32 @@ void CFM::relayingRFWaitState(bool validSignal)
   }
 }
 
-void CFM::kerchunkExtState(bool validSignal)
+void CFM::relayingRFWaitStateSimplex(bool validSignal)
+{
+  if (validSignal) {
+    io.setDecode(true);
+    io.setADCDetection(true);
+
+    DEBUG1("State to RELAYING_RF");
+    m_state = FS_RELAYING_RF;
+    m_ackDelayTimer.stop();
+  } else {
+    if (m_ackDelayTimer.isRunning() && m_ackDelayTimer.hasExpired()) {
+      DEBUG1("State to LISTENING");
+      m_state = FS_LISTENING;
+      m_ackDelayTimer.stop();
+      m_timeoutTimer.stop();
+    }
+  }
+}
+
+void CFM::kerchunkExtStateDuplex(bool validSignal)
 {
   if (validSignal) {
     if (m_kerchunkTimer.hasExpired()) {
       DEBUG1("State to RELAYING_EXT");
       m_state = FS_RELAYING_EXT;
       m_kerchunkTimer.stop();
-      if (!m_kerchunkTX) {
-        insertSilence(50U);
-
-        beginRelaying();
-
-        m_callsignTimer.start();
-
-        m_statusTimer.start();
-        serial.writeFMStatus(m_state);
-      }
       if (m_callsignAtStart && m_callsignAtLatch) {
         sendCallsign();
         m_callsignTimer.start();
@@ -543,10 +724,11 @@ void CFM::kerchunkExtState(bool validSignal)
     m_ackMinTimer.stop();
     m_callsignTimer.stop();
     m_statusTimer.stop();
+    m_needReverse = true;
   }
 }
 
-void CFM::relayingExtState(bool validSignal)
+void CFM::relayingExtStateDuplex(bool validSignal)
 {
   if (validSignal) {
     if (m_timeoutTimer.isRunning() && m_timeoutTimer.hasExpired()) {
@@ -568,7 +750,23 @@ void CFM::relayingExtState(bool validSignal)
   }
 }
 
-void CFM::relayingExtWaitState(bool validSignal)
+void CFM::relayingExtStateSimplex(bool validSignal)
+{
+  if (validSignal) {
+    if (m_timeoutTimer.isRunning() && m_timeoutTimer.hasExpired()) {
+      DEBUG1("State to TIMEOUT_EXT");
+      m_state = FS_TIMEOUT_EXT;
+
+      m_timeoutTimer.stop();
+    }
+  } else {
+    DEBUG1("State to RELAYING_WAIT_EXT");
+    m_state = FS_RELAYING_WAIT_EXT;
+    m_ackDelayTimer.start();
+  }
+}
+
+void CFM::relayingExtWaitStateDuplex(bool validSignal)
 {
   if (validSignal) {
     DEBUG1("State to RELAYING_EXT");
@@ -603,7 +801,24 @@ void CFM::relayingExtWaitState(bool validSignal)
   }
 }
 
-void CFM::hangState(bool validRFSignal, bool validExtSignal)
+void CFM::relayingExtWaitStateSimplex(bool validSignal)
+{
+  if (validSignal) {
+    DEBUG1("State to RELAYING_EXT");
+    m_state = FS_RELAYING_EXT;
+    m_ackDelayTimer.stop();
+  } else {
+    if (m_ackDelayTimer.isRunning() && m_ackDelayTimer.hasExpired()) {
+      DEBUG1("State to LISTENING");
+      m_state = FS_LISTENING;
+      m_ackDelayTimer.stop();
+      m_timeoutTimer.stop();
+      m_needReverse = true;
+    }
+  }
+}
+
+void CFM::hangStateDuplex(bool validRFSignal, bool validExtSignal)
 {
   if (validRFSignal) {
     io.setDecode(true);
@@ -633,7 +848,7 @@ void CFM::hangState(bool validRFSignal, bool validExtSignal)
         sendCallsign();
 
       m_callsignTimer.stop();
-
+      m_needReverse = true;
     }
   }
 
@@ -643,7 +858,7 @@ void CFM::hangState(bool validRFSignal, bool validExtSignal)
   }
 }
 
-void CFM::timeoutRFState(bool validSignal)
+void CFM::timeoutRFStateDuplex(bool validSignal)
 {
   if (!validSignal) {
     io.setDecode(false);
@@ -664,7 +879,20 @@ void CFM::timeoutRFState(bool validSignal)
   }
 }
 
-void CFM::timeoutRFWaitState(bool validSignal)
+void CFM::timeoutRFStateSimplex(bool validSignal)
+{
+  if (!validSignal) {
+    io.setDecode(false);
+    io.setADCDetection(false);
+
+    DEBUG1("State to TIMEOUT_WAIT_RF");
+    m_state = FS_TIMEOUT_WAIT_RF;
+
+    m_ackDelayTimer.start();
+  }
+}
+
+void CFM::timeoutRFWaitStateDuplex(bool validSignal)
 {
   if (validSignal) {
     io.setDecode(true);
@@ -693,7 +921,26 @@ void CFM::timeoutRFWaitState(bool validSignal)
   }
 }
 
-void CFM::timeoutExtState(bool validSignal)
+void CFM::timeoutRFWaitStateSimplex(bool validSignal)
+{
+  if (validSignal) {
+    io.setDecode(true);
+    io.setADCDetection(true);
+
+    DEBUG1("State to TIMEOUT_RF");
+    m_state = FS_TIMEOUT_RF;
+    m_ackDelayTimer.stop();
+  } else {
+    if (m_ackDelayTimer.isRunning() && m_ackDelayTimer.hasExpired()) {
+      DEBUG1("State to LISTENING");
+      m_state = FS_LISTENING;
+      m_ackDelayTimer.stop();
+      m_timeoutTimer.stop();
+    }
+  }
+}
+
+void CFM::timeoutExtStateDuplex(bool validSignal)
 {
   if (!validSignal) {
     DEBUG1("State to TIMEOUT_WAIT_EXT");
@@ -707,7 +954,16 @@ void CFM::timeoutExtState(bool validSignal)
   }
 }
 
-void CFM::timeoutExtWaitState(bool validSignal)
+void CFM::timeoutExtStateSimplex(bool validSignal)
+{
+  if (!validSignal) {
+    DEBUG1("State to TIMEOUT_WAIT_EXT");
+    m_state = FS_TIMEOUT_WAIT_EXT;
+    m_ackDelayTimer.start();
+  }
+}
+
+void CFM::timeoutExtWaitStateDuplex(bool validSignal)
 {
   if (validSignal) {
     DEBUG1("State to TIMEOUT_EXT");
@@ -732,6 +988,24 @@ void CFM::timeoutExtWaitState(bool validSignal)
     m_callsignTimer.start();
   }
 }
+
+void CFM::timeoutExtWaitStateSimplex(bool validSignal)
+{
+  if (validSignal) {
+    DEBUG1("State to TIMEOUT_EXT");
+    m_state = FS_TIMEOUT_EXT;
+    m_ackDelayTimer.stop();
+  } else {
+    if (m_ackDelayTimer.isRunning() && m_ackDelayTimer.hasExpired()) {
+      DEBUG1("State to LISTENING");
+      m_state = FS_LISTENING;
+      m_ackDelayTimer.stop();
+      m_timeoutTimer.stop();
+      m_needReverse = true;
+    }
+  }
+}
+
 void CFM::sendCallsign()
 {
   if (m_holdoffTimer.isRunning()) {

FM.h

@@ -29,8 +29,9 @@
 #include "FMTimer.h"
 #include "RingBuffer.h"
 #include "FMDirectForm1.h"
-#include "FMDownsampler.h"
+#include "FMDownSampler.h"
 #include "FMUpSampler.h"
+#include "FMNoiseSquelch.h"
 
 enum FM_STATE {
   FS_LISTENING,
@@ -60,7 +61,7 @@ public:
 
   uint8_t setCallsign(const char* callsign, uint8_t speed, uint16_t frequency, uint8_t time, uint8_t holdoff, uint8_t highLevel, uint8_t lowLevel, bool callsignAtStart, bool callsignAtEnd, bool callsignAtLatch);
   uint8_t setAck(const char* rfAck, uint8_t speed, uint16_t frequency, uint8_t minTime, uint16_t delay, uint8_t level);
-  uint8_t setMisc(uint16_t timeout, uint8_t timeoutLevel, uint8_t ctcssFrequency, uint8_t ctcssHighThreshold, uint8_t ctcssLowThreshold, uint8_t ctcssLevel, uint8_t kerchunkTime, bool kerchunkTX, uint8_t hangTime, bool useCOS, bool cosInvert, uint8_t rfAudioBoost, uint8_t maxDev, uint8_t rxLevel);
+  uint8_t setMisc(uint16_t timeout, uint8_t timeoutLevel, uint8_t ctcssFrequency, uint8_t ctcssHighThreshold, uint8_t ctcssLowThreshold, uint8_t ctcssLevel, uint8_t kerchunkTime, uint8_t hangTime, uint8_t accessMode, bool cosInvert, bool noiseSquelch, uint8_t squelchHighThreshold, uint8_t squelchLowThreshold, uint8_t rfAudioBoost, uint8_t maxDev, uint8_t rxLevel);
   uint8_t setExt(const char* ack, uint8_t audioBoost, uint8_t speed, uint16_t frequency, uint8_t level);
 
   uint8_t getSpace() const;
@@ -73,6 +74,7 @@ private:
   CFMKeyer             m_extAck;
   CFMCTCSSRX           m_ctcssRX;
   CFMCTCSSTX           m_ctcssTX;
+  CFMNoiseSquelch      m_squelch;
   CFMTimeout           m_timeoutTone;
   FM_STATE             m_state;
   bool                 m_callsignAtStart;
@@ -82,20 +84,22 @@ private:
   CFMTimer             m_timeoutTimer;
   CFMTimer             m_holdoffTimer;
   CFMTimer             m_kerchunkTimer;
-  bool                 m_kerchunkTX;
   CFMTimer             m_ackMinTimer;
   CFMTimer             m_ackDelayTimer;
   CFMTimer             m_hangTimer;
   CFMTimer             m_statusTimer;
+  CFMTimer             m_reverseTimer;
+  bool                 m_needReverse;
   CFMDirectFormI       m_filterStage1;
   CFMDirectFormI       m_filterStage2;
   CFMDirectFormI       m_filterStage3;
   CFMBlanking          m_blanking;
-  bool                 m_useCOS;
+  uint8_t              m_accessMode;
   bool                 m_cosInvert;
+  bool                 m_noiseSquelch;
   q15_t                m_rfAudioBoost;
   q15_t                m_extAudioBoost;
-  CFMDownsampler       m_downsampler;
+  CFMDownSampler       m_downSampler;
   bool                 m_extEnabled;
   q15_t                m_rxLevel;
   CRingBuffer<q15_t>   m_inputRFRB;
@@ -103,18 +107,31 @@ private:
   CFMUpSampler         m_inputExtRB;
 
   void stateMachine(bool validRFSignal, bool validExtSignal);
-  void listeningState(bool validRFSignal, bool validExtSignal);
-  void kerchunkRFState(bool validSignal);
-  void relayingRFState(bool validSignal);
-  void relayingRFWaitState(bool validSignal);
-  void timeoutRFState(bool validSignal);
-  void timeoutRFWaitState(bool validSignal);
-  void kerchunkExtState(bool validSignal);
-  void relayingExtState(bool validSignal);
-  void relayingExtWaitState(bool validSignal);
-  void timeoutExtState(bool validSignal);
-  void timeoutExtWaitState(bool validSignal);
-  void hangState(bool validRFSignal, bool validExtSignal);
+
+  void duplexStateMachine(bool validRFSignal, bool validExtSignal);
+  void listeningStateDuplex(bool validRFSignal, bool validExtSignal);
+  void kerchunkRFStateDuplex(bool validSignal);
+  void relayingRFStateDuplex(bool validSignal);
+  void relayingRFWaitStateDuplex(bool validSignal);
+  void timeoutRFStateDuplex(bool validSignal);
+  void timeoutRFWaitStateDuplex(bool validSignal);
+  void kerchunkExtStateDuplex(bool validSignal);
+  void relayingExtStateDuplex(bool validSignal);
+  void relayingExtWaitStateDuplex(bool validSignal);
+  void timeoutExtStateDuplex(bool validSignal);
+  void timeoutExtWaitStateDuplex(bool validSignal);
+  void hangStateDuplex(bool validRFSignal, bool validExtSignal);
+
+  void simplexStateMachine(bool validRFSignal, bool validExtSignal);
+  void listeningStateSimplex(bool validRFSignal, bool validExtSignal);
+  void relayingRFStateSimplex(bool validSignal);
+  void relayingRFWaitStateSimplex(bool validSignal);
+  void timeoutRFStateSimplex(bool validSignal);
+  void timeoutRFWaitStateSimplex(bool validSignal);
+  void relayingExtStateSimplex(bool validSignal);
+  void relayingExtWaitStateSimplex(bool validSignal);
+  void timeoutExtStateSimplex(bool validSignal);
+  void timeoutExtWaitStateSimplex(bool validSignal);
 
   void clock(uint8_t length);
 

FMCTCSSRX.cpp

@@ -87,7 +87,7 @@ m_lowThreshold(0),
 m_count(0U),
 m_q0(0),
 m_q1(0),
-m_result(CTS_NONE)
+m_state(false)
 {
 }
 
@@ -111,13 +111,11 @@ uint8_t CFMCTCSSRX::setParams(uint8_t frequency, uint8_t highThreshold, uint8_t
   return 0U;
 }
 
-uint8_t CFMCTCSSRX::process(q15_t sample)
+bool CFMCTCSSRX::process(q15_t sample)
 {
   //get more dynamic into the decoder by multiplying the sample by 1.5
   q31_t sample31 = q31_t(sample) +  (q31_t(sample) >> 1);
 
-  m_result &= ~CTS_READY;
-
   q31_t q2 = m_q1;
   m_q1 = m_q0;
 
@@ -149,33 +147,29 @@ uint8_t CFMCTCSSRX::process(q15_t sample)
     // value = m_q0 * m_q0 + m_q1 * m_q1 - m_q0 * m_q1 * m_coeffDivTwo * 2
     q31_t value = t2 + t4 - t9;
 
-    bool previousCTCSSValid = CTCSS_VALID(m_result);
+    bool previousState = m_state;
 
     q31_t threshold = m_highThreshold;
-    if (previousCTCSSValid)
+    if (previousState)
       threshold = m_lowThreshold;
 
-    m_result |= CTS_READY;
-    if (value >= threshold)
-      m_result |= CTS_VALID;
-    else
-      m_result &= ~CTS_VALID;
+    m_state = value >= threshold;
 
-    if (previousCTCSSValid != CTCSS_VALID(m_result))
-      DEBUG4("CTCSS Value / Threshold / Valid", value, threshold, CTCSS_VALID(m_result));
+    if (previousState != m_state)
+      DEBUG4("CTCSS Value / Threshold / Valid", value, threshold, m_state);
 
     m_count = 0U;
     m_q0 = 0;
     m_q1 = 0;
   }
 
-  return m_result;
+  return m_state;
 }
 
 void CFMCTCSSRX::reset()
 {
   m_q0 = 0;
   m_q1 = 0;
-  m_result = CTS_NONE;
-  m_count  = 0U;
+  m_state = false;
+  m_count = 0U;
 }

FMCTCSSRX.h

@@ -21,22 +21,13 @@
 
 #include "Config.h"
 
-const uint8_t CTS_NONE  = 0U;
-const uint8_t CTS_READY = 1U;
-const uint8_t CTS_VALID = 2U;
-
-#define CTCSS_READY(a) ((a & CTS_READY) != 0)
-#define CTCSS_NOT_READY(a) ((a & CTS_READY) == 0)
-#define CTCSS_VALID(a) ((a & CTS_VALID) != 0)
-#define CTCSS_NOT_VALID(a) ((a & CTS_VALID) == 0)
-
 class CFMCTCSSRX {
 public:
   CFMCTCSSRX();
 
   uint8_t setParams(uint8_t frequency, uint8_t highThreshold, uint8_t lowThreshold);
   
-  uint8_t process(q15_t sample);
+  bool process(q15_t sample);
 
   void reset();
 
@@ -47,7 +38,7 @@ private:
   uint16_t m_count;
   q31_t    m_q0;
   q31_t    m_q1;
-  uint8_t  m_result;
+  bool     m_state;
 };
 
 #endif

FMCTCSSTX.cpp

@@ -115,11 +115,14 @@ uint8_t CFMCTCSSTX::setParams(uint8_t frequency, uint8_t level)
   return 0U;
 }
 
-q15_t CFMCTCSSTX::getAudio()
+q15_t CFMCTCSSTX::getAudio(bool reverse)
 {
   q15_t sample = m_values[m_n++];
-  if(m_n >= m_length)
+  if (m_n >= m_length)
     m_n = 0U;
   
-  return sample;
+  if (reverse)
+    return -sample;
+  else
+    return sample;
 }

FMCTCSSTX.h

@@ -27,7 +27,7 @@ public:
 
   uint8_t setParams(uint8_t frequency, uint8_t level);
 
-  q15_t getAudio();
+  q15_t getAudio(bool reverse);
 
 private:
   q15_t*   m_values;

FMDownSampler.cpp

@@ -18,9 +18,9 @@
  */
 
 #include "Config.h"
-#include "FMDownsampler.h"
+#include "FMDownSampler.h"
 
-CFMDownsampler::CFMDownsampler(uint16_t length) :
+CFMDownSampler::CFMDownSampler(uint16_t length) :
 m_ringBuffer(length),
 m_samplePack(0U),
 m_samplePackPointer(NULL),
@@ -29,7 +29,7 @@ m_sampleIndex(0U)
   m_samplePackPointer = (uint8_t*)&m_samplePack;
 }
 
-void CFMDownsampler::addSample(q15_t sample)
+void CFMDownSampler::addSample(q15_t sample)
 {
   uint32_t usample = uint32_t(int32_t(sample) + 2048);
   //only take one of three samples
@@ -54,21 +54,21 @@ void CFMDownsampler::addSample(q15_t sample)
   }
 
   m_sampleIndex++;
-  if(m_sampleIndex >= 6U)//did we pack two samples ?
+  if (m_sampleIndex >= 6U)//did we pack two samples ?
       m_sampleIndex = 0U;  
 }
 
-bool CFMDownsampler::getPackedData(TSamplePairPack& data)
+bool CFMDownSampler::getPackedData(TSamplePairPack& data)
 {
   return m_ringBuffer.get(data);
 }
 
-uint16_t CFMDownsampler::getData()
+uint16_t CFMDownSampler::getData()
 {
   return m_ringBuffer.getData();
 }
 
-void CFMDownsampler::reset()
+void CFMDownSampler::reset()
 {
   m_sampleIndex = 0U;
-}
+}

FMDownSampler.h

@@ -24,12 +24,16 @@
 #include "RingBuffer.h"
 #include "FMSamplePairPack.h"
 
-class CFMDownsampler {
+class CFMDownSampler {
 public:
-  CFMDownsampler(uint16_t length);
+  CFMDownSampler(uint16_t length);
+
   void addSample(q15_t sample);
+
   bool getPackedData(TSamplePairPack& data);
+
   uint16_t getData();
+
   void reset();
 
 private:
@@ -40,3 +44,4 @@ private:
 };
 
 #endif
+

FMNoiseSquelch.cpp

@@ -0,0 +1,127 @@
+/*
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "Config.h"
+#include "Globals.h"
+#include "FMNoiseSquelch.h"
+
+// 4500Hz centre frequency
+const q31_t COEFF_DIV_TWO = 821806413;
+
+// 400Hz bandwidth
+const uint16_t N = 24000U / 400U;
+
+CFMNoiseSquelch::CFMNoiseSquelch() :
+m_highThreshold(0),
+m_lowThreshold(0),
+m_count(0U),
+m_q0(0),
+m_q1(0),
+m_state(false),
+m_validCount(0U)
+{
+
+}
+
+void CFMNoiseSquelch::setParams(uint8_t highThreshold, uint8_t lowThreshold)
+{
+  m_highThreshold = q31_t(highThreshold);
+  m_lowThreshold  = q31_t(lowThreshold);
+}
+
+bool CFMNoiseSquelch::process(q15_t sample)
+{
+  //get more dynamic into the decoder by multiplying the sample by 64
+  q31_t sample31 = q31_t(sample) << 6; //+  (q31_t(sample) >> 1);
+
+  q31_t q2 = m_q1;
+  m_q1 = m_q0;
+
+  // Q31 multiplication, t3 = m_coeffDivTwo * 2 * m_q1
+  q63_t t1 = COEFF_DIV_TWO * m_q1;
+  q31_t t2 = __SSAT((t1 >> 31), 31);
+  q31_t t3 = t2 * 2;
+
+  // m_q0 = m_coeffDivTwo * m_q1 * 2 - q2 + sample
+  m_q0 = t3 - q2 + sample31;
+
+  m_count++;
+  if (m_count == N) {
+    // Q31 multiplication, t2 = m_q0 * m_q0
+    q63_t t1 = q63_t(m_q0) * q63_t(m_q0);
+    q31_t t2 = __SSAT((t1 >> 31), 31);
+
+    // Q31 multiplication, t4 = m_q0 * m_q0
+    q63_t t3 = q63_t(m_q1) * q63_t(m_q1);
+    q31_t t4 = __SSAT((t3 >> 31), 31);
+
+    // Q31 multiplication, t9 = m_q0 * m_q1 * m_coeffDivTwo * 2
+    q63_t t5 = q63_t(m_q0) * q63_t(m_q1);
+    q31_t t6 = __SSAT((t5 >> 31), 31);
+    q63_t t7 = t6 * COEFF_DIV_TWO;
+    q31_t t8 = __SSAT((t7 >> 31), 31);
+    q31_t t9  = t8 * 2;
+
+    // value = m_q0 * m_q0 + m_q1 * m_q1 - m_q0 * m_q1 * m_coeffDivTwo * 2
+    q31_t value = t2 + t4 - t9;
+
+    bool previousState = m_state;
+
+    q31_t threshold = m_highThreshold;
+    if (previousState)
+      threshold = m_lowThreshold;
+
+    if (!m_state) {
+      if (value < threshold)
+        m_validCount++;
+      else
+        m_validCount = 0U;
+    }
+
+    if (m_state) {
+      if (value >= threshold)
+        m_invalidCount++;
+      else
+        m_invalidCount = 0U;
+    }
+
+    m_state = m_validCount >= 10U && m_invalidCount < 10U;
+
+    if(previousState && !m_state)
+      m_invalidCount = 0U;
+
+    if (previousState != m_state) {
+      DEBUG4("Noise Squelch Value / Threshold / Valid", value, threshold, m_state);
+      DEBUG3("Valid Count / Invalid Count", m_validCount, m_invalidCount);
+    }
+
+    m_count = 0U;
+    m_q0 = 0;
+    m_q1 = 0;
+  }
+
+  return m_state;
+}
+
+void CFMNoiseSquelch::reset()
+{
+  m_q0 = 0;
+  m_q1 = 0;
+  m_state = false;
+  m_count = 0U;
+}

FMNoiseSquelch.h

@@ -0,0 +1,45 @@
+/*
+ *   Copyright (C) 2020 by Jonathan Naylor G4KLX
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#if !defined(FMNOISESQUELCH_H)
+#define  FMNOISESQUELCH_H
+
+#include "Config.h"
+
+class CFMNoiseSquelch {
+public:
+  CFMNoiseSquelch();
+
+  void setParams(uint8_t highThreshold, uint8_t lowThreshold);
+  
+  bool process(q15_t sample);
+
+  void reset();
+
+private:
+  q31_t    m_highThreshold;
+  q31_t    m_lowThreshold;
+  uint16_t m_count;
+  q31_t    m_q0;
+  q31_t    m_q1;
+  bool     m_state;
+  uint8_t  m_validCount;
+  uint8_t  m_invalidCount;
+};
+
+#endif

FMTimeout.cpp

@@ -36,24 +36,22 @@ m_n(0U)
 
 void CFMTimeout::setParams(uint8_t level)
 {
-  m_level = q15_t(level * 128);
+  m_level = q15_t(level * 5);
 }
 
 q15_t CFMTimeout::getAudio()
 {
-  q15_t sample = 0U;
+  q15_t sample = 0;
   if (!m_running)
     return sample;
 
-  if (m_pos > 12000U) {
-    q31_t sample = BUSY_AUDIO[m_n] * m_level;
-    sample = q15_t(__SSAT((sample >> 15), 16));
+  if (m_pos >= 12000U) {
+    q31_t sample31 = BUSY_AUDIO[m_n] * m_level;
+    sample = q15_t(__SSAT((sample31 >> 15), 16));
 
     m_n++;
     if (m_n >= BUSY_AUDIO_LEN)
       m_n = 0U;
-  } else {
-    sample = 0U;
   }
 
   m_pos++;

Globals.h

@@ -52,6 +52,7 @@ enum MMDVM_STATE {
   STATE_NXDN      = 5,
   STATE_POCSAG    = 6,
   STATE_FM        = 10,
+  STATE_AX25      = 11,
 
   // Dummy states start at 90
   STATE_NXDNCAL1K = 91,
@@ -97,6 +98,8 @@ enum MMDVM_STATE {
 #include "CalPOCSAG.h"
 #include "CalRSSI.h"
 #include "CWIdTX.h"
+#include "AX25RX.h"
+#include "AX25TX.h"
 #include "Debug.h"
 #include "IO.h"
 #include "FM.h"
@@ -125,6 +128,7 @@ extern bool m_p25Enable;
 extern bool m_nxdnEnable;
 extern bool m_pocsagEnable;
 extern bool m_fmEnable;
+extern bool m_ax25Enable;
 
 extern bool m_duplex;
 
@@ -155,7 +159,9 @@ extern CNXDNTX nxdnTX;
 
 extern CPOCSAGTX pocsagTX;
 
-extern CFM fm;
+extern CFM     fm;
+extern CAX25RX ax25RX;
+extern CAX25TX ax25TX;
 
 extern CCalDStarRX calDStarRX;
 extern CCalDStarTX calDStarTX;
@@ -169,3 +175,4 @@ extern CCalRSSI    calRSSI;
 extern CCWIdTX cwIdTX;
 
 #endif
+

IO.cpp

@@ -81,8 +81,10 @@ m_p25TXLevel(128 * 128),
 m_nxdnTXLevel(128 * 128),
 m_pocsagTXLevel(128 * 128),
 m_fmTXLevel(128 * 128),
+m_ax25TXLevel(128 * 128),
 m_rxDCOffset(DC_OFFSET),
 m_txDCOffset(DC_OFFSET),
+m_useCOSAsLockout(false),
 m_ledCount(0U),
 m_ledValue(true),
 m_detect(false),
@@ -132,7 +134,7 @@ void CIO::selfTest()
 {
   bool ledValue = false;
 
-  for (uint8_t i = 0; i < 6; i++) {
+  for (uint8_t i = 0U; i < 6U; i++) {
     ledValue = !ledValue;
 
     // We exclude PTT to avoid trigger the transmitter
@@ -143,21 +145,34 @@ void CIO::selfTest()
     setDMRInt(ledValue);
     setYSFInt(ledValue);
     setP25Int(ledValue);
+#if !defined(USE_ALTERNATE_NXDN_LEDS)
     setNXDNInt(ledValue);
+#endif
+#if !defined(USE_ALTERNATE_POCSAG_LEDS)
     setPOCSAGInt(ledValue);
+#endif
+#if !defined(USE_ALTERNATE_FM_LEDS)
     setFMInt(ledValue);
+#endif
 #endif
     delayInt(250);
   }
 
 #if defined(MODE_LEDS)
-  setDStarInt(true);
+  setDStarInt(false);
   setDMRInt(false);
   setYSFInt(false);
   setP25Int(false);
+#if !defined(USE_ALTERNATE_NXDN_LEDS)
   setNXDNInt(false);
+#endif
+#if !defined(USE_ALTERNATE_POCSAG_LEDS)
   setPOCSAGInt(false);
+#endif
+#if !defined(USE_ALTERNATE_FM_LEDS)
   setFMInt(false);
+#endif
+  setDStarInt(true);
 
   delayInt(250);
   setDMRInt(true);
@@ -219,7 +234,7 @@ void CIO::start()
 
   m_started = true;
 
-  setMode();
+  setMode(STATE_IDLE);
 }
 
 void CIO::process()
@@ -231,8 +246,7 @@ void CIO::process()
       if (m_modemState == STATE_DSTAR || m_modemState == STATE_DMR || m_modemState == STATE_YSF || m_modemState == STATE_P25 || m_modemState == STATE_NXDN || m_modemState == STATE_POCSAG) {
         if (m_modemState == STATE_DMR && m_tx)
           dmrTX.setStart(false);
-        m_modemState = STATE_IDLE;
-        setMode();
+        setMode(STATE_IDLE);
       }
 
       m_watchdog = 0U;
@@ -256,9 +270,8 @@ void CIO::process()
     return;
   }
 
-#if defined(USE_COS_AS_LOCKOUT)
-  m_lockout = getCOSInt();
-#endif
+  if (m_useCOSAsLockout)
+    m_lockout = getCOSInt();
 
   // Switch off the transmitter if needed
   if (m_txBuffer.getData() == 0U && m_tx) {
@@ -364,6 +377,14 @@ void CIO::process()
         fm.samples(cos, dcSamples, RX_BLOCK_SIZE);
 #else
         fm.samples(cos, samples, RX_BLOCK_SIZE);
+#endif
+      }
+
+      if (m_ax25Enable) {
+#if defined(USE_DCBLOCKER)
+        ax25RX.samples(dcSamples, RX_BLOCK_SIZE);
+#else
+        ax25RX.samples(samples, RX_BLOCK_SIZE);
 #endif
       }
     } else if (m_modemState == STATE_DSTAR) {
@@ -428,8 +449,12 @@ void CIO::process()
       bool cos = getCOSInt();
 #if defined(USE_DCBLOCKER)
       fm.samples(cos, dcSamples, RX_BLOCK_SIZE);
+      if (m_ax25Enable)
+        ax25RX.samples(dcSamples, RX_BLOCK_SIZE);
 #else
       fm.samples(cos, samples, RX_BLOCK_SIZE);
+      if (m_ax25Enable)
+        ax25RX.samples(samples, RX_BLOCK_SIZE);
 #endif
     } else if (m_modemState == STATE_DSTARCAL) {
       q15_t GMSKVals[RX_BLOCK_SIZE];
@@ -480,6 +505,9 @@ void CIO::write(MMDVM_STATE mode, q15_t* samples, uint16_t length, const uint8_t
     case STATE_FM:
       txLevel = m_fmTXLevel;
       break;
+    case STATE_AX25:
+      txLevel = m_ax25TXLevel;
+      break;
     default:
       txLevel = m_cwIdTXLevel;
       break;
@@ -519,20 +547,37 @@ void CIO::setADCDetection(bool detect)
   m_detect = detect;
 }
 
-void CIO::setMode()
+void CIO::setMode(MMDVM_STATE state)
 {
+  if (state == m_modemState)
+    return;
+
 #if defined(MODE_LEDS)
-  setDStarInt(m_modemState == STATE_DSTAR);
-  setDMRInt(m_modemState   == STATE_DMR);
-  setYSFInt(m_modemState   == STATE_YSF);
-  setP25Int(m_modemState   == STATE_P25);
-  setNXDNInt(m_modemState  == STATE_NXDN);
-  setPOCSAGInt(m_modemState  == STATE_POCSAG);
-  setFMInt(m_modemState == STATE_FM);
+  switch (m_modemState) {
+    case STATE_DSTAR:  setDStarInt(false);  break;
+    case STATE_DMR:    setDMRInt(false);    break;
+    case STATE_YSF:    setYSFInt(false);    break;
+    case STATE_P25:    setP25Int(false);    break;
+    case STATE_NXDN:   setNXDNInt(false);   break;
+    case STATE_POCSAG: setPOCSAGInt(false); break;
+    case STATE_FM:     setFMInt(false);     break;
+  }
+
+  switch (state) {
+    case STATE_DSTAR:  setDStarInt(true);  break;
+    case STATE_DMR:    setDMRInt(true);    break;
+    case STATE_YSF:    setYSFInt(true);    break;
+    case STATE_P25:    setP25Int(true);    break;
+    case STATE_NXDN:   setNXDNInt(true);   break;
+    case STATE_POCSAG: setPOCSAGInt(true); break;
+    case STATE_FM:     setFMInt(true);     break;
+  }
 #endif
+
+  m_modemState = state;
 }
 
-void CIO::setParameters(bool rxInvert, bool txInvert, bool pttInvert, uint8_t rxLevel, uint8_t cwIdTXLevel, uint8_t dstarTXLevel, uint8_t dmrTXLevel, uint8_t ysfTXLevel, uint8_t p25TXLevel, uint8_t nxdnTXLevel, uint8_t pocsagTXLevel, uint8_t fmTXLevel, int16_t txDCOffset, int16_t rxDCOffset)
+void CIO::setParameters(bool rxInvert, bool txInvert, bool pttInvert, uint8_t rxLevel, uint8_t cwIdTXLevel, uint8_t dstarTXLevel, uint8_t dmrTXLevel, uint8_t ysfTXLevel, uint8_t p25TXLevel, uint8_t nxdnTXLevel, uint8_t pocsagTXLevel, uint8_t fmTXLevel, uint8_t ax25TXLevel, int16_t txDCOffset, int16_t rxDCOffset, bool useCOSAsLockout)
 {
   m_pttInvert = pttInvert;
 
@@ -545,9 +590,12 @@ void CIO::setParameters(bool rxInvert, bool txInvert, bool pttInvert, uint8_t rx
   m_nxdnTXLevel   = q15_t(nxdnTXLevel * 128);
   m_pocsagTXLevel = q15_t(pocsagTXLevel * 128);
   m_fmTXLevel     = q15_t(fmTXLevel * 128);
+  m_ax25TXLevel   = q15_t(ax25TXLevel * 128);
 
   m_rxDCOffset   = DC_OFFSET + rxDCOffset;
   m_txDCOffset   = DC_OFFSET + txDCOffset;
+
+  m_useCOSAsLockout = useCOSAsLockout;
   
   if (rxInvert)
     m_rxLevel = -m_rxLevel;

IO.h

@@ -42,11 +42,11 @@ public:
 
   void setDecode(bool dcd);
   void setADCDetection(bool detect);
-  void setMode();
+  void setMode(MMDVM_STATE state);
   
   void interrupt();
 
-  void setParameters(bool rxInvert, bool txInvert, bool pttInvert, uint8_t rxLevel, uint8_t cwIdTXLevel, uint8_t dstarTXLevel, uint8_t dmrTXLevel, uint8_t ysfTXLevel, uint8_t p25TXLevel, uint8_t nxdnTXLevel, uint8_t pocsagTXLevel, uint8_t fmTXLevel, int16_t txDCOffset, int16_t rxDCOffset);
+  void setParameters(bool rxInvert, bool txInvert, bool pttInvert, uint8_t rxLevel, uint8_t cwIdTXLevel, uint8_t dstarTXLevel, uint8_t dmrTXLevel, uint8_t ysfTXLevel, uint8_t p25TXLevel, uint8_t nxdnTXLevel, uint8_t pocsagTXLevel, uint8_t fmTXLevel, uint8_t ax25TXLevel, int16_t txDCOffset, int16_t rxDCOffset, bool useCOSAsLockout);
 
   void getOverflow(bool& adcOverflow, bool& dacOverflow);
 
@@ -91,10 +91,13 @@ private:
   q15_t                m_nxdnTXLevel;
   q15_t                m_pocsagTXLevel;
   q15_t                m_fmTXLevel;
+  q15_t                m_ax25TXLevel;
 
   uint16_t             m_rxDCOffset;
   uint16_t             m_txDCOffset;
 
+  bool                 m_useCOSAsLockout;
+
   uint32_t             m_ledCount;
   bool                 m_ledValue;
 

IOPins.h

@@ -62,9 +62,12 @@
 #elif defined(DRCC_DVM_NQF)
     #include "pins/pins_f4_drcc_nqf.h"
 
+#elif defined(STM32F4_EDA_405) || defined(STM32F4_EDA_446)
+    #include "pins/pins_f4_stm32eda.h"
+
 #else
     #error "A valid board type macro need to be defined."
 
 #endif
 
-#endif  //#ifndef _IO_PINS_H
+#endif  //#ifndef _IO_PINS_H

IOSTM_CMSIS.cpp

@@ -41,7 +41,6 @@ YSF      PB8    output
 P25      PB9    output
 NXDN     PB10   output
 POCSAG   PB11   output
-FM       PB12   output
 
 RX       PB0    analog input (ADC1_8)
 RSSI     PB1    analog input (ADC2_9)
@@ -85,9 +84,6 @@ USART1_RXD PA10  input (AF)
 #define PIN_POCSAG        11
 #define PORT_POCSAG       GPIOB
 #define BB_POCSAG         *((bitband_t)BITBAND_PERIPH(&PORT_POCSAG->ODR, PIN_POCSAG))
-#define PIN_FM            14
-#define PORT_FM           GPIOB
-#define BB_FM             *((bitband_t)BITBAND_PERIPH(&PORT_FM->ODR, PIN_FM))
 
 #define PIN_RX            0
 #define PIN_RX_ADC_CH     8
@@ -158,35 +154,16 @@ void GPIOConfigPin(GPIO_TypeDef *port_ptr, uint32_t pin, uint32_t mode_cnf_value
 #if defined(STM32F1_POG)
 void FancyLEDEffect()
 {
-  int ledCount = 10;
-
-  bitband_t foo[] = {&BB_LED, &BB_COSLED, &BB_PTT, &BB_DMR, &BB_DSTAR, &BB_YSF, &BB_P25,
-#if defined(USE_ALTERNATE_NXDN_LEDS)
-	NULL,
-#else
-	&BB_NXDN,
-#endif
-#if defined(USE_ALTERNATE_POCSAG_LEDS)
-	NULL,
-#else
-  	&BB_POCSAG,
-#endif
-#if defined(USE_ALTERNATE_FM_LEDS)
-	NULL};
-#else
-	&BB_FM};
-#endif
-
-  for(int i=0; i<ledCount; i++){
-    if(foo[i] != NULL)
-      *foo[i] = 0x01;
+  bitband_t foo[] = {&BB_LED, &BB_COSLED, &BB_PTT, &BB_DMR, &BB_DSTAR, &BB_YSF, &BB_P25};
+   
+  for(int i=0; i<7; i++){
+    *foo[i] = 0x01;
   }
   GPIOConfigPin(PORT_USART1_TXD, PIN_USART1_TXD, GPIO_CRL_MODE0_1);
   *((bitband_t)BITBAND_PERIPH(&PORT_USART1_TXD->ODR, PIN_USART1_TXD)) = 0x00;
   delay(SystemCoreClock/1000*100);
-  for(int i=0; i<ledCount; i++){
-    if(foo[i] != NULL)
-      *foo[i] = 0x00;
+  for(int i=0; i<7; i++){
+    *foo[i] = 0x00;
   }
   *((bitband_t)BITBAND_PERIPH(&PORT_USART1_TXD->ODR, PIN_USART1_TXD)) = 0x01;
   delay(SystemCoreClock/1000*20);
@@ -195,22 +172,18 @@ void FancyLEDEffect()
   *((bitband_t)BITBAND_PERIPH(&PORT_USART1_TXD->ODR, PIN_USART1_TXD)) = 0x01;
   
   *foo[0] = 0x01;
-  for(int i=1; i<ledCount; i++){
+  for(int i=1; i<7; i++){
     delay(SystemCoreClock/1000*10);
-    if (foo[i-1] != NULL)
-      *foo[i-1] = 0x00;
-    if (foo[i] != NULL)
-      *foo[i] = 0x01;
+    *foo[i-1] = 0x00;
+    *foo[i] = 0x01;
   }
-  for(int i=ledCount - 2; i>=0; i--) {
+  for(int i=5; i>=0; i--){
     delay(SystemCoreClock/1000*10);
-    if (foo[i+1] != NULL)
-      *foo[i+1] = 0x00;
-    if (foo[i] != NULL)
-      *foo[i] = 0x01;
+    *foo[i+1] = 0x00;
+    *foo[i] = 0x01;
   }
   delay(SystemCoreClock/1000*10);
-  *foo[0] = 0x00;
+  *foo[5+1-6] = 0x00;
   *((bitband_t)BITBAND_PERIPH(&PORT_USART1_TXD->ODR, PIN_USART1_TXD)) = 0x00;
   delay(SystemCoreClock/1000*10);
   *((bitband_t)BITBAND_PERIPH(&PORT_USART1_TXD->ODR, PIN_USART1_TXD)) = 0x01;
@@ -255,9 +228,6 @@ static inline void GPIOInit()
 #if !defined(USE_ALTERNATE_POCSAG_LEDS)
   GPIOConfigPin(PORT_POCSAG, PIN_POCSAG, GPIO_CRL_MODE0_1);
 #endif
-#if !defined(USE_ALTERNATE_FM_LEDS)
-  GPIOConfigPin(PORT_FM,     PIN_FM,     GPIO_CRL_MODE0_1);
-#endif
 
   GPIOConfigPin(PORT_RX, PIN_RX, 0);
 #if defined(SEND_RSSI_DATA)
@@ -494,8 +464,6 @@ void CIO::setFMInt(bool on)
 #if defined(USE_ALTERNATE_FM_LEDS)
   BB_DSTAR = !!on;
   BB_YSF   = !!on;
-#else
-  BB_FM = !!on;
 #endif
 }
 

MMDVM.cpp

@@ -33,6 +33,7 @@ bool m_p25Enable    = true;
 bool m_nxdnEnable   = true;
 bool m_pocsagEnable = true;
 bool m_fmEnable     = true;
+bool m_ax25Enable   = true;
 
 bool m_duplex = true;
 
@@ -61,6 +62,8 @@ CNXDNTX    nxdnTX;
 CPOCSAGTX  pocsagTX;
 
 CFM        fm;
+CAX25RX    ax25RX;
+CAX25TX    ax25TX;
 
 CCalDStarRX calDStarRX;
 CCalDStarTX calDStarTX;
@@ -110,6 +113,9 @@ void loop()
   if (m_pocsagEnable && (m_modemState == STATE_POCSAG || pocsagTX.busy()))
     pocsagTX.process();
 
+  if (m_ax25Enable && (m_modemState == STATE_IDLE || m_modemState == STATE_FM))
+    ax25TX.process();
+
   if (m_fmEnable && m_modemState == STATE_FM)
     fm.process();
 

MMDVM.ino

@@ -30,6 +30,7 @@ bool m_p25Enable    = true;
 bool m_nxdnEnable   = true;
 bool m_pocsagEnable = true;
 bool m_fmEnable     = true;
+bool m_ax25Enable   = true;
 
 bool m_duplex = true;
 
@@ -58,6 +59,8 @@ CNXDNTX    nxdnTX;
 CPOCSAGTX  pocsagTX;
 
 CFM        fm;
+CAX25RX    ax25RX;
+CAX25TX    ax25TX;
 
 CCalDStarRX calDStarRX;
 CCalDStarTX calDStarTX;
@@ -107,6 +110,9 @@ void loop()
   if (m_pocsagEnable && (m_modemState == STATE_POCSAG || pocsagTX.busy()))
     pocsagTX.process();
 
+  if (m_ax25Enable && (m_modemState == STATE_IDLE || m_modemState == STATE_FM))
+    ax25TX.process();
+
   if (m_fmEnable && m_modemState == STATE_FM)
     fm.process();
 

Makefile

@@ -139,6 +139,10 @@ DEFS_DVM=-DUSE_STDPERIPH_DRIVER -DSTM32F4XX -DSTM32F446xx -DSTM32F4_DVM -DHSE_VA
 DEFS_RPT_HAT_TGO=-DUSE_STDPERIPH_DRIVER -DSTM32F4XX -DSTM32F40_41xxx -DSTM32F4_RPT_HAT_TGO -DHSE_VALUE=$(OSC) -DMADEBYMAKEFILE
 # DRCC_DVM BG7NQF board:
 DEFS_DRCC_DVM=-DUSE_STDPERIPH_DRIVER -DSTM32F4XX -DSTM32F446xx -DDRCC_DVM -DHSE_VALUE=$(OSC) -DMADEBYMAKEFILE
+# WA0EDA F405 MTR2K, MASTR3 board:
+DEFS_EDA_405=-DUSE_STDPERIPH_DRIVER -DSTM32F4XX -DSTM32F40_41xxx -DSTM32F4_EDA_405 -DHSE_VALUE=$(OSC) -DMADEBYMAKEFILE
+# WA0EDA F446 MTR2K, MASTR3 board:
+DEFS_EDA_446=-DUSE_STDPERIPH_DRIVER -DSTM32F4XX -DSTM32F446xx -DSTM32F4_EDA_446 -DHSE_VALUE=$(OSC) -DMADEBYMAKEFILE
 
 
 # Build compiler flags
@@ -155,7 +159,7 @@ LDFLAGS_F722 =-T stm32f722_link.ld $(MCFLAGS_F7) --specs=nosys.specs $(INCLUDES_
 # Common flags
 CFLAGS=-Os -ffunction-sections -fdata-sections -fno-builtin -Wno-implicit -DCUSTOM_NEW -DNO_EXCEPTIONS
 CXXFLAGS=-Os -fno-exceptions -ffunction-sections -fdata-sections -fno-builtin -fno-rtti -DCUSTOM_NEW -DNO_EXCEPTIONS
-LDFLAGS=-Os --specs=nano.specs
+LDFLAGS=-Os --specs=nano.specs -Wl,-Map=bin/mmdvm.map
 
 # Build Rules
 .PHONY: all release dis pi pi-f722 f4m nucleo f767 dvm drcc_nqf clean
@@ -229,6 +233,18 @@ drcc_nqf: CXXFLAGS+=$(CXXFLAGS_F4) $(DEFS_DRCC_DVM) -DDRCC_DVM_NQF
 drcc_nqf: LDFLAGS+=$(LDFLAGS_F4)
 drcc_nqf: release_f4
 
+eda405: GitVersion.h
+eda405: CFLAGS+=$(CFLAGS_F4) $(DEFS_EDA_405)
+eda405: CXXFLAGS+=$(CXXFLAGS_F4) $(DEFS_EDA_405)
+eda405: LDFLAGS+=$(LDFLAGS_F4)
+eda405: release_f4
+
+eda446: GitVersion.h
+eda446: CFLAGS+=$(CFLAGS_F4) $(DEFS_EDA_446)
+eda446: CXXFLAGS+=$(CXXFLAGS_F4) $(DEFS_EDA_446)
+eda446: LDFLAGS+=$(LDFLAGS_F4)
+eda446: release_f4
+
 release_f4: $(BINDIR)
 release_f4: $(OBJDIR_F4)
 release_f4: $(BINDIR)/$(BINHEX_F4)
@@ -350,6 +366,8 @@ endif
 
 deploy-f4m: deploy-pi
 deploy-dvm: deploy-pi
+deploy-eda405: deploy-pi
+deploy-eda446: deploy-pi
 
 deploy-pi-f7:
 ifneq ($(wildcard /usr/local/bin/stm32flash),)

NXDNTX.cpp

@@ -123,7 +123,7 @@ void CNXDNTX::process()
   }
 }
 
-uint8_t CNXDNTX::writeData(const uint8_t* data, uint8_t length)
+uint8_t CNXDNTX::writeData(const uint8_t* data, uint16_t length)
 {
   if (length != (NXDN_FRAME_LENGTH_BYTES + 1U))
     return 4U;

NXDNTX.h

@@ -27,7 +27,7 @@ class CNXDNTX {
 public:
   CNXDNTX();
 
-  uint8_t writeData(const uint8_t* data, uint8_t length);
+  uint8_t writeData(const uint8_t* data, uint16_t length);
 
   void process();
 

P25TX.cpp

@@ -120,7 +120,7 @@ void CP25TX::process()
   }
 }
 
-uint8_t CP25TX::writeData(const uint8_t* data, uint8_t length)
+uint8_t CP25TX::writeData(const uint8_t* data, uint16_t length)
 {
   if (length < (P25_TERM_FRAME_LENGTH_BYTES + 1U))
     return 4U;

P25TX.h

@@ -27,7 +27,7 @@ class CP25TX {
 public:
   CP25TX();
 
-  uint8_t writeData(const uint8_t* data, uint8_t length);
+  uint8_t writeData(const uint8_t* data, uint16_t length);
 
   void process();
 

POCSAGTX.cpp

@@ -96,7 +96,7 @@ bool CPOCSAGTX::busy()
     return false;
 }
 
-uint8_t CPOCSAGTX::writeData(const uint8_t* data, uint8_t length)
+uint8_t CPOCSAGTX::writeData(const uint8_t* data, uint16_t length)
 {
   if (length != POCSAG_FRAME_LENGTH_BYTES)
     return 4U;

POCSAGTX.h

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015-2019 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015-2020 by Jonathan Naylor G4KLX
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -27,7 +27,7 @@ class CPOCSAGTX {
 public:
   CPOCSAGTX();
 
-  uint8_t writeData(const uint8_t* data, uint8_t length);
+  uint8_t writeData(const uint8_t* data, uint16_t length);
 
   void writeByte(uint8_t c);
 

README.md

@@ -1,7 +1,17 @@
-This is the source code of the MMDVM firmware that supports D-Star, DMR, System Fusion, P25, NXDN, and POCSAG modes.
+This is the source code of the MMDVM firmware that supports D-Star, DMR,
+System Fusion, P25, NXDN, POCSAG, and FM modes.
 
-It runs on the Arduino Due, the ST-Micro STM32F1xxx, STM32F4xxx and STM32F7xxx processors, as well as the Teensy 3.1/3.2/3.5/3.6. What these platforms have in common is the use of an ARM Cortex-M3 or M4 processor with a clock speed greater than 70 MHz, and access to at least one analogue to digital converter and one digital to analogue converter.
+It runs on the Arduino Due, the ST-Micro STM32F1xxx, STM32F4xxx and STM32F7xxx
+processors, as well as the Teensy 3.1/3.2/3.5/3.6. What these platforms have in
+common is the use of an ARM Cortex-M3, M4, or M7 processors with a clock speed
+greater than 70 MHz, and access to at least one analogue to digital converter
+and one digital to analogue converter.
 
-In order to build this software for the Arduino Due, you will need to edit a file within the Arduino GUI and that is detailed in the BUILD.txt file. The STM32 support is being supplied via the Coocox IDE with ARM GCC. The Teensy support uses Teensyduino.
+In order to build this software for the Arduino Due, you will need to edit a
+file within the Arduino GUI and that is detailed in the BUILD.txt file. The
+STM32 support is being supplied via the ARM GCC compiler. The Teensy support
+uses Teensyduino.
 
-This software is licenced under the GPL v2 and is intended for amateur and educational use only. Use of this software for commercial purposes is strictly forbidden.
+This software is licenced under the GPL v2 and is intended for amateur and
+educational use only. Use of this software for commercial purposes is strictly
+forbidden.

SerialPort.cpp

@@ -65,6 +65,8 @@ const uint8_t MMDVM_NXDN_LOST    = 0x41U;
 
 const uint8_t MMDVM_POCSAG_DATA  = 0x50U;
 
+const uint8_t MMDVM_AX25_DATA    = 0x55U;
+
 const uint8_t MMDVM_FM_PARAMS1   = 0x60U;
 const uint8_t MMDVM_FM_PARAMS2   = 0x61U;
 const uint8_t MMDVM_FM_PARAMS3   = 0x62U;
@@ -107,7 +109,7 @@ const uint8_t MMDVM_DEBUG5       = 0xF5U;
 #define	HW_TYPE	"MMDVM"
 #endif
 
-#define DESCRIPTION "20200620 (D-Star/DMR/System Fusion/P25/NXDN/POCSAG/FM)"
+#define DESCRIPTION "20200901 (D-Star/DMR/System Fusion/P25/NXDN/POCSAG/FM/AX.25)"
 
 #if defined(GITVERSION)
 #define concat(h, a, b, c) h " " a " " b " GitID #" c ""
@@ -162,7 +164,7 @@ void CSerialPort::getStatus()
 
   // Send all sorts of interesting internal values
   reply[0U]  = MMDVM_FRAME_START;
-  reply[1U]  = 14U;
+  reply[1U]  = 15U;
   reply[2U]  = MMDVM_GET_STATUS;
 
   reply[3U]  = 0x00U;
@@ -180,6 +182,8 @@ void CSerialPort::getStatus()
     reply[3U] |= 0x20U;
   if (m_fmEnable)
     reply[3U] |= 0x40U;
+  if (m_ax25Enable)
+    reply[3U] |= 0x80U;
 
   reply[4U]  = uint8_t(m_modemState);
 
@@ -249,7 +253,12 @@ void CSerialPort::getStatus()
   else
     reply[13U] = 0U;
 
-  writeInt(1U, reply, 14);
+  if (m_ax25Enable)
+    reply[14U] = ax25TX.getSpace();
+  else
+    reply[14U] = 0U;
+
+  writeInt(1U, reply, 15);
 }
 
 void CSerialPort::getVersion()
@@ -271,16 +280,17 @@ void CSerialPort::getVersion()
   writeInt(1U, reply, count);
 }
 
-uint8_t CSerialPort::setConfig(const uint8_t* data, uint8_t length)
+uint8_t CSerialPort::setConfig(const uint8_t* data, uint16_t length)
 {
-  if (length < 21U)
+  if (length < 26U)
     return 4U;
 
-  bool rxInvert  = (data[0U] & 0x01U) == 0x01U;
-  bool txInvert  = (data[0U] & 0x02U) == 0x02U;
-  bool pttInvert = (data[0U] & 0x04U) == 0x04U;
-  bool ysfLoDev  = (data[0U] & 0x08U) == 0x08U;
-  bool simplex   = (data[0U] & 0x80U) == 0x80U;
+  bool rxInvert        = (data[0U] & 0x01U) == 0x01U;
+  bool txInvert        = (data[0U] & 0x02U) == 0x02U;
+  bool pttInvert       = (data[0U] & 0x04U) == 0x04U;
+  bool ysfLoDev        = (data[0U] & 0x08U) == 0x08U;
+  bool useCOSAsLockout = (data[0U] & 0x20U) == 0x20U;
+  bool simplex         = (data[0U] & 0x80U) == 0x80U;
 
   m_debug = (data[0U] & 0x10U) == 0x10U;
 
@@ -291,6 +301,7 @@ uint8_t CSerialPort::setConfig(const uint8_t* data, uint8_t length)
   bool nxdnEnable   = (data[1U] & 0x10U) == 0x10U;
   bool pocsagEnable = (data[1U] & 0x20U) == 0x20U;
   bool fmEnable     = (data[1U] & 0x40U) == 0x40U;
+  bool ax25Enable   = (data[1U] & 0x80U) == 0x80U;
 
   uint8_t txDelay = data[2U];
   if (txDelay > 50U)
@@ -344,6 +355,18 @@ uint8_t CSerialPort::setConfig(const uint8_t* data, uint8_t length)
 
   uint8_t nxdnTXHang    = data[20U];
 
+  uint8_t ax25TXLevel   = data[21U];
+
+  int8_t ax25RXTwist    = int8_t(data[22U]) - 128;
+  if (ax25RXTwist < -4 || ax25RXTwist > 10)
+    return 4U;
+
+  uint8_t ax25TXDelay   = data[23U];
+
+  uint8_t ax25SlotTime  = data[24U];
+
+  uint8_t ax25PPersist  = data[25U];
+
   setMode(modemState);
 
   m_dstarEnable  = dstarEnable;
@@ -353,6 +376,7 @@ uint8_t CSerialPort::setConfig(const uint8_t* data, uint8_t length)
   m_nxdnEnable   = nxdnEnable;
   m_pocsagEnable = pocsagEnable;
   m_fmEnable     = fmEnable;
+  m_ax25Enable   = ax25Enable;
   m_duplex       = !simplex;
 
   dstarTX.setTXDelay(txDelay);
@@ -361,6 +385,7 @@ uint8_t CSerialPort::setConfig(const uint8_t* data, uint8_t length)
   dmrDMOTX.setTXDelay(txDelay);
   nxdnTX.setTXDelay(txDelay);
   pocsagTX.setTXDelay(txDelay);
+  ax25TX.setTXDelay(ax25TXDelay);
 
   dmrTX.setColorCode(colorCode);
   dmrRX.setColorCode(colorCode);
@@ -371,15 +396,16 @@ uint8_t CSerialPort::setConfig(const uint8_t* data, uint8_t length)
   ysfTX.setParams(ysfLoDev, ysfTXHang);
   p25TX.setParams(p25TXHang);
   nxdnTX.setParams(nxdnTXHang);
+  ax25RX.setParams(ax25RXTwist, ax25SlotTime, ax25PPersist);
 
-  io.setParameters(rxInvert, txInvert, pttInvert, rxLevel, cwIdTXLevel, dstarTXLevel, dmrTXLevel, ysfTXLevel, p25TXLevel, nxdnTXLevel, pocsagTXLevel, fmTXLevel, txDCOffset, rxDCOffset);
+  io.setParameters(rxInvert, txInvert, pttInvert, rxLevel, cwIdTXLevel, dstarTXLevel, dmrTXLevel, ysfTXLevel, p25TXLevel, nxdnTXLevel, pocsagTXLevel, fmTXLevel, ax25TXLevel, txDCOffset, rxDCOffset, useCOSAsLockout);
 
   io.start();
 
   return 0U;
 }
 
-uint8_t CSerialPort::setFMParams1(const uint8_t* data, uint8_t length)
+uint8_t CSerialPort::setFMParams1(const uint8_t* data, uint16_t length)
 {
   if (length < 8U)
     return 4U;
@@ -404,7 +430,7 @@ uint8_t CSerialPort::setFMParams1(const uint8_t* data, uint8_t length)
   return fm.setCallsign(callsign, speed, frequency, time, holdoff, highLevel, lowLevel, callAtStart, callAtEnd, callAtLatch);
 }
 
-uint8_t CSerialPort::setFMParams2(const uint8_t* data, uint8_t length)
+uint8_t CSerialPort::setFMParams2(const uint8_t* data, uint16_t length)
 {
   if (length < 6U)
     return 4U;
@@ -424,9 +450,9 @@ uint8_t CSerialPort::setFMParams2(const uint8_t* data, uint8_t length)
   return fm.setAck(ack, speed, frequency, minTime, delay, level);
 }
 
-uint8_t CSerialPort::setFMParams3(const uint8_t* data, uint8_t length)
+uint8_t CSerialPort::setFMParams3(const uint8_t* data, uint16_t length)
 {
-  if (length < 12U)
+  if (length < 14U)
     return 4U;
 
   uint16_t timeout        = data[0U] * 5U;
@@ -440,18 +466,21 @@ uint8_t CSerialPort::setFMParams3(const uint8_t* data, uint8_t length)
   uint8_t  kerchunkTime   = data[6U];
   uint8_t  hangTime       = data[7U];
 
-  bool     useCOS         = (data[8U] & 0x01U) == 0x01U;
-  bool     cosInvert      = (data[8U] & 0x02U) == 0x02U;
-  bool     kerchunkTX     = (data[8U] & 0x04U) == 0x04U;
+  uint8_t  accessMode     = data[8U] & 0x0FU;
+  bool     noiseSquelch   = (data[8U] & 0x40U) == 0x40U;
+  bool     cosInvert      = (data[8U] & 0x80U) == 0x80U;
 
   uint8_t  rfAudioBoost   = data[9U];
   uint8_t  maxDev         = data[10U];
   uint8_t  rxLevel        = data[11U];
 
-  return fm.setMisc(timeout, timeoutLevel, ctcssFrequency, ctcssHighThreshold, ctcssLowThreshold, ctcssLevel, kerchunkTime, kerchunkTX, hangTime, useCOS, cosInvert, rfAudioBoost, maxDev, rxLevel);
+  uint8_t  squelchHighThreshold = data[12U];
+  uint8_t  squelchLowThreshold  = data[13U];
+
+  return fm.setMisc(timeout, timeoutLevel, ctcssFrequency, ctcssHighThreshold, ctcssLowThreshold, ctcssLevel, kerchunkTime, hangTime, accessMode, cosInvert, noiseSquelch, squelchHighThreshold, squelchLowThreshold, rfAudioBoost, maxDev, rxLevel);
 }
 
-uint8_t CSerialPort::setFMParams4(const uint8_t* data, uint8_t length)
+uint8_t CSerialPort::setFMParams4(const uint8_t* data, uint16_t length)
 {
   if (length < 4U)
     return 4U;
@@ -470,7 +499,7 @@ uint8_t CSerialPort::setFMParams4(const uint8_t* data, uint8_t length)
   return fm.setExt(ack, audioBoost, speed, frequency, level);
 }
 
-uint8_t CSerialPort::setMode(const uint8_t* data, uint8_t length)
+uint8_t CSerialPort::setMode(const uint8_t* data, uint16_t length)
 {
   if (length < 1U)
     return 4U;
@@ -596,9 +625,7 @@ void CSerialPort::setMode(MMDVM_STATE modemState)
 
   cwIdTX.reset();
 
-  m_modemState = modemState;
-
-  io.setMode();
+  io.setMode(modemState);
 }
 
 void CSerialPort::start()
@@ -621,15 +648,25 @@ void CSerialPort::process()
         m_buffer[0U] = c;
         m_ptr = 1U;
         m_len = 0U;
-      }
-      else {
+      } else {
         m_ptr = 0U;
         m_len = 0U;
       }
     } else if (m_ptr == 1U) {
-      // Handle the frame length
+      // Handle the frame length, 1/2
       m_len = m_buffer[m_ptr] = c;
       m_ptr = 2U;
+    } else if (m_ptr == 2U) {
+      // Handle the frame length, 2/2
+      m_buffer[m_ptr] = c;
+      m_ptr = 3U;
+
+      if (m_len == 0U)
+        m_len = c + 255U;
+
+      // The full packet has been received, process it
+      if (m_ptr == m_len)
+        processMessage(m_buffer + 3U, m_len - 3U);
     } else {
       // Any other bytes are added to the buffer
       m_buffer[m_ptr] = c;
@@ -637,328 +674,10 @@ void CSerialPort::process()
 
       // The full packet has been received, process it
       if (m_ptr == m_len) {
-        uint8_t err = 2U;
-
-        switch (m_buffer[2U]) {
-          case MMDVM_GET_STATUS:
-            getStatus();
-            break;
-
-          case MMDVM_GET_VERSION:
-            getVersion();
-            break;
-
-          case MMDVM_SET_CONFIG:
-            err = setConfig(m_buffer + 3U, m_len - 3U);
-            if (err == 0U)
-              sendACK();
-            else
-              sendNAK(err);
-            break;
-
-          case MMDVM_SET_MODE:
-            err = setMode(m_buffer + 3U, m_len - 3U);
-            if (err == 0U)
-              sendACK();
-            else
-              sendNAK(err);
-            break;
-
-          case MMDVM_SET_FREQ:
-            sendACK();
-            break;
-
-          case MMDVM_FM_PARAMS1:
-            err = setFMParams1(m_buffer + 3U, m_len - 3U);
-            if (err == 0U) {
-              sendACK();
-            } else {
-              DEBUG2("Received invalid FM params 1", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_FM_PARAMS2:
-            err = setFMParams2(m_buffer + 3U, m_len - 3U);
-            if (err == 0U) {
-              sendACK();
-            } else {
-              DEBUG2("Received invalid FM params 2", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_FM_PARAMS3:
-            err = setFMParams3(m_buffer + 3U, m_len - 3U);
-            if (err == 0U) {
-              sendACK();
-            } else {
-              DEBUG2("Received invalid FM params 3", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_FM_PARAMS4:
-            err = setFMParams4(m_buffer + 3U, m_len - 3U);
-            if (err == 0U) {
-              sendACK();
-            } else {
-              DEBUG2("Received invalid FM params 4", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_CAL_DATA:
-            if (m_modemState == STATE_DSTARCAL)
-              err = calDStarTX.write(m_buffer + 3U, m_len - 3U);
-            if (m_modemState == STATE_DMRCAL || m_modemState == STATE_LFCAL || m_modemState == STATE_DMRCAL1K || m_modemState == STATE_DMRDMO1K)
-              err = calDMR.write(m_buffer + 3U, m_len - 3U);
-            if (m_modemState == STATE_FMCAL10K || m_modemState == STATE_FMCAL12K || m_modemState == STATE_FMCAL15K || m_modemState == STATE_FMCAL20K || m_modemState == STATE_FMCAL25K || m_modemState == STATE_FMCAL30K)
-              err = calFM.write(m_buffer + 3U, m_len - 3U);
-            if (m_modemState == STATE_P25CAL1K)
-              err = calP25.write(m_buffer + 3U, m_len - 3U);
-            if (m_modemState == STATE_NXDNCAL1K)
-              err = calNXDN.write(m_buffer + 3U, m_len - 3U);
-            if (m_modemState == STATE_POCSAGCAL)
-              err = calPOCSAG.write(m_buffer + 3U, m_len - 3U);
-            if (err == 0U) {
-              sendACK();
-            } else {
-              DEBUG2("Received invalid calibration data", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_SEND_CWID:
-            err = 5U;
-            if (m_modemState == STATE_IDLE)
-              err = cwIdTX.write(m_buffer + 3U, m_len - 3U);
-            if (err != 0U) {
-              DEBUG2("Invalid CW Id data", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_DSTAR_HEADER:
-            if (m_dstarEnable) {
-              if (m_modemState == STATE_IDLE || m_modemState == STATE_DSTAR)
-                err = dstarTX.writeHeader(m_buffer + 3U, m_len - 3U);
-            }
-            if (err == 0U) {
-              if (m_modemState == STATE_IDLE)
-                setMode(STATE_DSTAR);
-            } else {
-              DEBUG2("Received invalid D-Star header", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_DSTAR_DATA:
-            if (m_dstarEnable) {
-              if (m_modemState == STATE_IDLE || m_modemState == STATE_DSTAR)
-                err = dstarTX.writeData(m_buffer + 3U, m_len - 3U);
-            }
-            if (err == 0U) {
-              if (m_modemState == STATE_IDLE)
-                setMode(STATE_DSTAR);
-            } else {
-              DEBUG2("Received invalid D-Star data", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_DSTAR_EOT:
-            if (m_dstarEnable) {
-              if (m_modemState == STATE_IDLE || m_modemState == STATE_DSTAR)
-                err = dstarTX.writeEOT();
-            }
-            if (err == 0U) {
-              if (m_modemState == STATE_IDLE)
-                setMode(STATE_DSTAR);
-            } else {
-              DEBUG2("Received invalid D-Star EOT", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_DMR_DATA1:
-            if (m_dmrEnable) {
-              if (m_modemState == STATE_IDLE || m_modemState == STATE_DMR) {
-                if (m_duplex)
-                  err = dmrTX.writeData1(m_buffer + 3U, m_len - 3U);
-              }
-            }
-            if (err == 0U) {
-              if (m_modemState == STATE_IDLE)
-                setMode(STATE_DMR);
-            } else {
-              DEBUG2("Received invalid DMR data", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_DMR_DATA2:
-            if (m_dmrEnable) {
-              if (m_modemState == STATE_IDLE || m_modemState == STATE_DMR) {
-                if (m_duplex)
-                  err = dmrTX.writeData2(m_buffer + 3U, m_len - 3U);
-                else
-                  err = dmrDMOTX.writeData(m_buffer + 3U, m_len - 3U);
-              }
-            }
-            if (err == 0U) {
-              if (m_modemState == STATE_IDLE)
-                setMode(STATE_DMR);
-            } else {
-              DEBUG2("Received invalid DMR data", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_DMR_START:
-            if (m_dmrEnable) {
-              err = 4U;
-              if (m_len == 4U) {
-                if (m_buffer[3U] == 0x01U && m_modemState == STATE_DMR) {
-                  if (!m_tx)
-                    dmrTX.setStart(true);
-                  err = 0U;
-                } else if (m_buffer[3U] == 0x00U && m_modemState == STATE_DMR) {
-                  if (m_tx)
-                    dmrTX.setStart(false);
-                  err = 0U;
-                }
-              }
-            }
-            if (err != 0U) {
-              DEBUG2("Received invalid DMR start", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_DMR_SHORTLC:
-            if (m_dmrEnable)
-              err = dmrTX.writeShortLC(m_buffer + 3U, m_len - 3U);
-            if (err != 0U) {
-              DEBUG2("Received invalid DMR Short LC", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_DMR_ABORT:
-            if (m_dmrEnable)
-              err = dmrTX.writeAbort(m_buffer + 3U, m_len - 3U);
-            if (err != 0U) {
-              DEBUG2("Received invalid DMR Abort", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_YSF_DATA:
-            if (m_ysfEnable) {
-              if (m_modemState == STATE_IDLE || m_modemState == STATE_YSF)
-                err = ysfTX.writeData(m_buffer + 3U, m_len - 3U);
-            }
-            if (err == 0U) {
-              if (m_modemState == STATE_IDLE)
-                setMode(STATE_YSF);
-            } else {
-              DEBUG2("Received invalid System Fusion data", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_P25_HDR:
-            if (m_p25Enable) {
-              if (m_modemState == STATE_IDLE || m_modemState == STATE_P25)
-                err = p25TX.writeData(m_buffer + 3U, m_len - 3U);
-            }
-            if (err == 0U) {
-              if (m_modemState == STATE_IDLE)
-                setMode(STATE_P25);
-            } else {
-              DEBUG2("Received invalid P25 header", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_P25_LDU:
-            if (m_p25Enable) {
-              if (m_modemState == STATE_IDLE || m_modemState == STATE_P25)
-                err = p25TX.writeData(m_buffer + 3U, m_len - 3U);
-            }
-            if (err == 0U) {
-              if (m_modemState == STATE_IDLE)
-                setMode(STATE_P25);
-            } else {
-              DEBUG2("Received invalid P25 LDU", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_NXDN_DATA:
-            if (m_nxdnEnable) {
-              if (m_modemState == STATE_IDLE || m_modemState == STATE_NXDN)
-                err = nxdnTX.writeData(m_buffer + 3U, m_len - 3U);
-            }
-            if (err == 0U) {
-              if (m_modemState == STATE_IDLE)
-                setMode(STATE_NXDN);
-            } else {
-              DEBUG2("Received invalid NXDN data", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_POCSAG_DATA:
-            if (m_pocsagEnable) {
-              if (m_modemState == STATE_IDLE || m_modemState == STATE_POCSAG)
-                err = pocsagTX.writeData(m_buffer + 3U, m_len - 3U);
-            }
-            if (err == 0U) {
-              if (m_modemState == STATE_IDLE)
-                setMode(STATE_POCSAG);
-            } else {
-              DEBUG2("Received invalid POCSAG data", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_FM_DATA:
-            if (m_fmEnable) {
-              if (m_modemState == STATE_IDLE || m_modemState == STATE_FM)
-                err = fm.writeData(m_buffer + 3U, m_len - 3U);
-            }
-            if (err == 0U) {
-              if (m_modemState == STATE_IDLE)
-                setMode(STATE_FM);
-            } else {
-              DEBUG2("Received invalid FM data", err);
-              sendNAK(err);
-            }
-            break;
-
-          case MMDVM_TRANSPARENT:
-          case MMDVM_QSO_INFO:
-            // Do nothing on the MMDVM.
-            break;
-
-#if defined(SERIAL_REPEATER)
-          case MMDVM_SERIAL: {
-            for (uint8_t i = 3U; i < m_len; i++)
-              m_repeat.put(m_buffer[i]);
-            }
-            break;
-#endif
-
-          default:
-            // Handle this, send a NAK back
-            sendNAK(1U);
-            break;
-        }
-
-        m_ptr = 0U;
-        m_len = 0U;
+        if (m_len > 255U)
+          processMessage(m_buffer + 4U, m_len - 4U);
+        else
+          processMessage(m_buffer + 3U, m_len - 3U);
       }
     }
   }
@@ -988,6 +707,343 @@ void CSerialPort::process()
 #endif
 }
 
+void CSerialPort::processMessage(const uint8_t* buffer, uint16_t length)
+{
+  uint8_t err = 2U;
+
+  switch (m_buffer[2U]) {
+    case MMDVM_GET_STATUS:
+      getStatus();
+      break;
+
+    case MMDVM_GET_VERSION:
+      getVersion();
+      break;
+
+    case MMDVM_SET_CONFIG:
+      err = setConfig(buffer, length);
+      if (err == 0U)
+        sendACK();
+      else
+        sendNAK(err);
+      break;
+
+    case MMDVM_SET_MODE:
+      err = setMode(buffer, length);
+      if (err == 0U)
+        sendACK();
+      else
+        sendNAK(err);
+      break;
+
+    case MMDVM_SET_FREQ:
+      sendACK();
+      break;
+
+    case MMDVM_FM_PARAMS1:
+      err = setFMParams1(buffer, length);
+      if (err == 0U) {
+        sendACK();
+      } else {
+        DEBUG2("Received invalid FM params 1", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_FM_PARAMS2:
+      err = setFMParams2(buffer, length);
+      if (err == 0U) {
+        sendACK();
+      } else {
+        DEBUG2("Received invalid FM params 2", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_FM_PARAMS3:
+      err = setFMParams3(buffer, length);
+      if (err == 0U) {
+        sendACK();
+      } else {
+        DEBUG2("Received invalid FM params 3", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_FM_PARAMS4:
+      err = setFMParams4(buffer, length);
+      if (err == 0U) {
+        sendACK();
+      } else {
+        DEBUG2("Received invalid FM params 4", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_CAL_DATA:
+      if (m_modemState == STATE_DSTARCAL)
+        err = calDStarTX.write(buffer, length);
+      if (m_modemState == STATE_DMRCAL || m_modemState == STATE_LFCAL || m_modemState == STATE_DMRCAL1K || m_modemState == STATE_DMRDMO1K)
+        err = calDMR.write(buffer, length);
+      if (m_modemState == STATE_FMCAL10K || m_modemState == STATE_FMCAL12K || m_modemState == STATE_FMCAL15K || m_modemState == STATE_FMCAL20K || m_modemState == STATE_FMCAL25K || m_modemState == STATE_FMCAL30K)
+        err = calFM.write(buffer, length);
+      if (m_modemState == STATE_P25CAL1K)
+        err = calP25.write(buffer, length);
+      if (m_modemState == STATE_NXDNCAL1K)
+        err = calNXDN.write(buffer, length);
+      if (m_modemState == STATE_POCSAGCAL)
+        err = calPOCSAG.write(buffer, length);
+      if (err == 0U) {
+        sendACK();
+      } else {
+        DEBUG2("Received invalid calibration data", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_SEND_CWID:
+      err = 5U;
+      if (m_modemState == STATE_IDLE)
+        err = cwIdTX.write(buffer, length);
+      if (err != 0U) {
+        DEBUG2("Invalid CW Id data", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_DSTAR_HEADER:
+      if (m_dstarEnable) {
+        if (m_modemState == STATE_IDLE || m_modemState == STATE_DSTAR)
+          err = dstarTX.writeHeader(buffer, length);
+      }
+      if (err == 0U) {
+        if (m_modemState == STATE_IDLE)
+          setMode(STATE_DSTAR);
+      } else {
+        DEBUG2("Received invalid D-Star header", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_DSTAR_DATA:
+      if (m_dstarEnable) {
+        if (m_modemState == STATE_IDLE || m_modemState == STATE_DSTAR)
+          err = dstarTX.writeData(buffer, length);
+      }
+      if (err == 0U) {
+        if (m_modemState == STATE_IDLE)
+          setMode(STATE_DSTAR);
+      } else {
+        DEBUG2("Received invalid D-Star data", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_DSTAR_EOT:
+      if (m_dstarEnable) {
+        if (m_modemState == STATE_IDLE || m_modemState == STATE_DSTAR)
+          err = dstarTX.writeEOT();
+      }
+      if (err == 0U) {
+        if (m_modemState == STATE_IDLE)
+          setMode(STATE_DSTAR);
+      } else {
+        DEBUG2("Received invalid D-Star EOT", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_DMR_DATA1:
+      if (m_dmrEnable) {
+        if (m_modemState == STATE_IDLE || m_modemState == STATE_DMR) {
+          if (m_duplex)
+            err = dmrTX.writeData1(buffer, length);
+        }
+      }
+      if (err == 0U) {
+        if (m_modemState == STATE_IDLE)
+          setMode(STATE_DMR);
+      } else {
+        DEBUG2("Received invalid DMR data", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_DMR_DATA2:
+      if (m_dmrEnable) {
+        if (m_modemState == STATE_IDLE || m_modemState == STATE_DMR) {
+          if (m_duplex)
+            err = dmrTX.writeData2(buffer, length);
+          else
+            err = dmrDMOTX.writeData(buffer, length);
+        }
+      }
+      if (err == 0U) {
+        if (m_modemState == STATE_IDLE)
+          setMode(STATE_DMR);
+      } else {
+        DEBUG2("Received invalid DMR data", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_DMR_START:
+      if (m_dmrEnable) {
+        err = 4U;
+        if (m_len == 4U) {
+          if (m_buffer[3U] == 0x01U && m_modemState == STATE_DMR) {
+            if (!m_tx)
+              dmrTX.setStart(true);
+            err = 0U;
+          } else if (m_buffer[3U] == 0x00U && m_modemState == STATE_DMR) {
+            if (m_tx)
+              dmrTX.setStart(false);
+            err = 0U;
+          }
+        }
+      }
+      if (err != 0U) {
+        DEBUG2("Received invalid DMR start", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_DMR_SHORTLC:
+      if (m_dmrEnable)
+        err = dmrTX.writeShortLC(buffer, length);
+      if (err != 0U) {
+        DEBUG2("Received invalid DMR Short LC", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_DMR_ABORT:
+      if (m_dmrEnable)
+        err = dmrTX.writeAbort(buffer, length);
+      if (err != 0U) {
+        DEBUG2("Received invalid DMR Abort", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_YSF_DATA:
+      if (m_ysfEnable) {
+        if (m_modemState == STATE_IDLE || m_modemState == STATE_YSF)
+          err = ysfTX.writeData(buffer, length);
+      }
+      if (err == 0U) {
+        if (m_modemState == STATE_IDLE)
+          setMode(STATE_YSF);
+      } else {
+        DEBUG2("Received invalid System Fusion data", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_P25_HDR:
+      if (m_p25Enable) {
+        if (m_modemState == STATE_IDLE || m_modemState == STATE_P25)
+          err = p25TX.writeData(buffer, length);
+      }
+      if (err == 0U) {
+        if (m_modemState == STATE_IDLE)
+          setMode(STATE_P25);
+      } else {
+        DEBUG2("Received invalid P25 header", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_P25_LDU:
+      if (m_p25Enable) {
+        if (m_modemState == STATE_IDLE || m_modemState == STATE_P25)
+          err = p25TX.writeData(buffer, length);
+      }
+      if (err == 0U) {
+        if (m_modemState == STATE_IDLE)
+          setMode(STATE_P25);
+      } else {
+        DEBUG2("Received invalid P25 LDU", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_NXDN_DATA:
+      if (m_nxdnEnable) {
+        if (m_modemState == STATE_IDLE || m_modemState == STATE_NXDN)
+          err = nxdnTX.writeData(buffer, length);
+      }
+      if (err == 0U) {
+        if (m_modemState == STATE_IDLE)
+          setMode(STATE_NXDN);
+      } else {
+        DEBUG2("Received invalid NXDN data", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_POCSAG_DATA:
+      if (m_pocsagEnable) {
+        if (m_modemState == STATE_IDLE || m_modemState == STATE_POCSAG)
+          err = pocsagTX.writeData(buffer, length);
+      }
+      if (err == 0U) {
+        if (m_modemState == STATE_IDLE)
+          setMode(STATE_POCSAG);
+      } else {
+        DEBUG2("Received invalid POCSAG data", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_FM_DATA:
+      if (m_fmEnable) {
+        if (m_modemState == STATE_IDLE || m_modemState == STATE_FM)
+          err = fm.writeData(m_buffer + 3U, m_len - 3U);
+      }
+      if (err == 0U) {
+        if (m_modemState == STATE_IDLE)
+          setMode(STATE_FM);
+      } else {
+        DEBUG2("Received invalid FM data", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_AX25_DATA:
+      if (m_ax25Enable) {
+        if (m_modemState == STATE_IDLE || m_modemState == STATE_FM)
+          err = ax25TX.writeData(buffer, length);
+      }
+      if (err != 0U) {
+        DEBUG2("Received invalid AX.25 data", err);
+        sendNAK(err);
+      }
+      break;
+
+    case MMDVM_TRANSPARENT:
+    case MMDVM_QSO_INFO:
+      // Do nothing on the MMDVM.
+      break;
+
+#if defined(SERIAL_REPEATER)
+    case MMDVM_SERIAL: {
+      for (uint8_t i = 3U; i < m_len; i++)
+        m_repeat.put(m_buffer[i]);
+      }
+      break;
+#endif
+
+    default:
+      // Handle this, send a NAK back
+      sendNAK(1U);
+      break;
+  }
+
+  m_ptr = 0U;
+  m_len = 0U;
+}
+
 void CSerialPort::writeDStarHeader(const uint8_t* header, uint8_t length)
 {
   if (m_modemState != STATE_DSTAR && m_modemState != STATE_IDLE)
@@ -1250,7 +1306,7 @@ void CSerialPort::writeNXDNLost()
   writeInt(1U, reply, 3);
 }
 
-void CSerialPort::writeFMData(const uint8_t* data, uint8_t length)
+void CSerialPort::writeFMData(const uint8_t* data, uint16_t length)
 {
   if (m_modemState != STATE_FM && m_modemState != STATE_IDLE)
     return;
@@ -1258,19 +1314,28 @@ void CSerialPort::writeFMData(const uint8_t* data, uint8_t length)
   if (!m_fmEnable)
     return;
 
-  uint8_t reply[255U];
+  uint8_t reply[512U];
 
   reply[0U] = MMDVM_FRAME_START;
-  reply[1U] = 0U;
-  reply[2U] = MMDVM_FM_DATA;
 
-  uint8_t count = 3U;
-  for (uint8_t i = 0U; i < length; i++, count++)
-    reply[count] = data[i];
+  if (length > 252U) {
+    reply[1U] = 0U;
+    reply[2U] = (length + 4U) - 255U;
+    reply[3U] = MMDVM_FM_DATA;
 
-  reply[1U] = count;
+    for (uint8_t i = 0U; i < length; i++)
+      reply[i + 4U] = data[i];
 
-  writeInt(1U, reply, count);
+    writeInt(1U, reply, length + 4U);
+  } else {
+    reply[1U] = length + 3U;
+    reply[2U] = MMDVM_FM_DATA;
+
+    for (uint8_t i = 0U; i < length; i++)
+      reply[i + 3U] = data[i];
+
+    writeInt(1U, reply, length + 3U);
+  }
 }
 
 void CSerialPort::writeFMStatus(uint8_t status)
@@ -1308,6 +1373,38 @@ void CSerialPort::writeFMEOT()
   writeInt(1U, reply, 3U);
 }
 
+void CSerialPort::writeAX25Data(const uint8_t* data, uint16_t length)
+{
+  if (m_modemState != STATE_FM && m_modemState != STATE_IDLE)
+    return;
+
+  if (!m_ax25Enable)
+    return;
+
+  uint8_t reply[512U];
+
+  reply[0U] = MMDVM_FRAME_START;
+
+  if (length > 252U) {
+    reply[1U] = 0U;
+    reply[2U] = (length + 4U) - 255U;
+    reply[3U] = MMDVM_AX25_DATA;
+
+    for (uint8_t i = 0U; i < length; i++)
+      reply[i + 4U] = data[i];
+
+    writeInt(1U, reply, length + 4U);
+  } else {
+    reply[1U] = length + 3U;
+    reply[2U] = MMDVM_AX25_DATA;
+
+    for (uint8_t i = 0U; i < length; i++)
+      reply[i + 3U] = data[i];
+
+    writeInt(1U, reply, length + 3U);
+  }
+}
+
 void CSerialPort::writeCalData(const uint8_t* data, uint8_t length)
 {
   if (m_modemState != STATE_DSTARCAL)

SerialPort.h

@@ -54,7 +54,9 @@ public:
   void writeNXDNData(const uint8_t* data, uint8_t length);
   void writeNXDNLost();
 
-  void writeFMData(const uint8_t* data, uint8_t length);
+  void writeAX25Data(const uint8_t* data, uint16_t length);
+
+  void writeFMData(const uint8_t* data, uint16_t length);
   void writeFMStatus(uint8_t status);
   void writeFMEOT();
 
@@ -68,9 +70,9 @@ public:
   void writeDebug(const char* text, int16_t n1, int16_t n2, int16_t n3, int16_t n4);
 
 private:
-  uint8_t   m_buffer[256U];
-  uint8_t   m_ptr;
-  uint8_t   m_len;
+  uint8_t   m_buffer[512U];
+  uint16_t  m_ptr;
+  uint16_t  m_len;
   bool      m_debug;
   CRingBuffer<uint8_t> m_repeat;
 
@@ -78,13 +80,14 @@ private:
   void    sendNAK(uint8_t err);
   void    getStatus();
   void    getVersion();
-  uint8_t setConfig(const uint8_t* data, uint8_t length);
-  uint8_t setMode(const uint8_t* data, uint8_t length);
+  uint8_t setConfig(const uint8_t* data, uint16_t length);
+  uint8_t setMode(const uint8_t* data, uint16_t length);
   void    setMode(MMDVM_STATE modemState);
-  uint8_t setFMParams1(const uint8_t* data, uint8_t length);
-  uint8_t setFMParams2(const uint8_t* data, uint8_t length);
-  uint8_t setFMParams3(const uint8_t* data, uint8_t length);
-  uint8_t setFMParams4(const uint8_t* data, uint8_t length);
+  uint8_t setFMParams1(const uint8_t* data, uint16_t length);
+  uint8_t setFMParams2(const uint8_t* data, uint16_t length);
+  uint8_t setFMParams3(const uint8_t* data, uint16_t length);
+  uint8_t setFMParams4(const uint8_t* data, uint16_t length);
+  void    processMessage(const uint8_t* data, uint16_t length);
 
   // Hardware versions
   void    beginInt(uint8_t n, int speed);

SerialSTM.cpp

@@ -48,7 +48,7 @@ extern "C" {
 }
 
 /* ************* USART1 ***************** */
-#if defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_F7M) || defined(STM32F722_PI) || defined(STM32F722_RPT_HAT) || defined(STM32F4_DVM) || (defined(STM32F4_NUCLEO) && defined(STM32F4_NUCLEO_ARDUINO_HEADER)) || defined(DRCC_DVM)
+#if defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_F7M) || defined(STM32F722_PI) || defined(STM32F722_RPT_HAT) || defined(STM32F4_DVM) || (defined(STM32F4_NUCLEO) && defined(STM32F4_NUCLEO_ARDUINO_HEADER)) || defined(DRCC_DVM) || defined(STM32F4_EDA_405) || defined(STM32F4_EDA_446)
 
 
 static CSTMUART m_USART1;
@@ -305,7 +305,7 @@ void CSerialPort::beginInt(uint8_t n, int speed)
       case 1U:
          #if defined(STM32F4_DISCOVERY) || defined(STM32F7_NUCLEO)
          InitUSART3(speed);
-         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_RPT_HAT) || defined(STM32F4_DVM)
+         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_RPT_HAT) || defined(STM32F4_DVM) || defined(STM32F4_EDA_405) || defined(STM32F4_EDA_446)
          InitUSART1(speed);
          #elif defined(STM32F4_NUCLEO) || defined(STM32F4_RPT_HAT_TGO)
          InitUSART2(speed);
@@ -333,7 +333,7 @@ int CSerialPort::availableInt(uint8_t n)
       case 1U:
          #if defined(STM32F4_DISCOVERY) || defined(STM32F7_NUCLEO)
          return m_USART3.availble();//AvailUSART3();
-         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_RPT_HAT) || defined(STM32F4_DVM)
+         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_RPT_HAT) || defined(STM32F4_DVM) || defined(STM32F4_EDA_405) || defined(STM32F4_EDA_446)
          return m_USART1.available();//AvailUSART1();
          #elif defined(STM32F4_NUCLEO) || defined(STM32F4_RPT_HAT_TGO)
          return m_USART2.available();//AvailUSART2();
@@ -359,7 +359,7 @@ int CSerialPort::availableForWriteInt(uint8_t n)
       case 1U:
          #if defined(STM32F4_DISCOVERY) || defined(STM32F7_NUCLEO)
          return m_USART3.availableForWrite(); //AvailForWriteUSART3();
-         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_RPT_HAT) || defined(STM32F4_DVM)
+         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_RPT_HAT) || defined(STM32F4_DVM) || defined(STM32F4_EDA_405) || defined(STM32F4_EDA_446)
          return m_USART1.availableForWrite(); //AvailForWriteUSART1();
          #elif defined(STM32F4_NUCLEO) || defined(STM32F4_RPT_HAT_TGO)
          return m_USART2.availableForWrite();//AvailForWriteUSART2();
@@ -385,7 +385,7 @@ uint8_t CSerialPort::readInt(uint8_t n)
       case 1U:
          #if defined(STM32F4_DISCOVERY) || defined(STM32F7_NUCLEO)
          return m_USART3.read();//ReadUSART3();
-         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_RPT_HAT) || defined(STM32F4_DVM)
+         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_RPT_HAT) || defined(STM32F4_DVM) || defined(STM32F4_EDA_405) || defined(STM32F4_EDA_446)
          return m_USART1.read();//ReadUSART1();
          #elif defined(STM32F4_NUCLEO) || defined(STM32F4_RPT_HAT_TGO)
          return m_USART2.read();//ReadUSART2();
@@ -413,7 +413,7 @@ void CSerialPort::writeInt(uint8_t n, const uint8_t* data, uint16_t length, bool
          m_USART3.write(data, length); //WriteUSART3(data, length);
          if (flush)
             m_USART3.flush();//TXSerialFlush3();
-         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_RPT_HAT) || defined(STM32F4_DVM)
+         #elif defined(STM32F4_PI) || defined(STM32F4_F4M) || defined(STM32F722_PI) || defined(STM32F722_F7M) || defined(STM32F722_RPT_HAT) || defined(STM32F4_DVM) || defined(STM32F4_EDA_405) || defined(STM32F4_EDA_446)
          m_USART1.write(data, length);//WriteUSART1(data, length);
          if (flush)
             m_USART1.flush();//TXSerialFlush1();
@@ -448,3 +448,4 @@ void CSerialPort::writeInt(uint8_t n, const uint8_t* data, uint16_t length, bool
 }
 
 #endif
+

YSFRX.cpp

@@ -36,7 +36,7 @@ const uint8_t NOAVEPTR = 99U;
 
 const uint16_t NOENDPTR = 9999U;
 
-const unsigned int MAX_SYNC_FRAMES = 4U + 1U;
+const unsigned int MAX_SYNC_FRAMES = 1U + 1U;
 
 CYSFRX::CYSFRX() :
 m_state(YSFRXS_NONE),

YSFTX.cpp

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2009-2018 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2009-2018,2020 by Jonathan Naylor G4KLX
  *   Copyright (C) 2017 by Andy Uribe CA6JAU
  *
  *   This program is free software; you can redistribute it and/or modify
@@ -117,7 +117,7 @@ void CYSFTX::process()
   }
 }
 
-uint8_t CYSFTX::writeData(const uint8_t* data, uint8_t length)
+uint8_t CYSFTX::writeData(const uint8_t* data, uint16_t length)
 {
   if (length != (YSF_FRAME_LENGTH_BYTES + 1U))
     return 4U;

YSFTX.h

@@ -1,5 +1,5 @@
 /*
- *   Copyright (C) 2015,2016,2017 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2015,2016,2017,2020 by Jonathan Naylor G4KLX
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -27,7 +27,7 @@ class CYSFTX {
 public:
   CYSFTX();
 
-  uint8_t writeData(const uint8_t* data, uint8_t length);
+  uint8_t writeData(const uint8_t* data, uint16_t length);
 
   void process();
 

pins/pins_f4_drcc_nqf.h

@@ -22,36 +22,40 @@
 /*
 Pin definitions for DRCC_DVM BG7NQF  board rev1
 
-PTT      PB12   output
-LED_PTT  PB4    output
-LED_COS  PB5    output
-LED_SRV  PB10   output
-COS      PB13   input
+TX/PTT_LED  PB12   output
+RX/COS_LED  PB5    output
+STATUS_LED  PB10   output
 
-DSTAR    N/A
-DMR      N/A
-YSF      N/A
-P25      N/A
-NXDN     N/A
-POCSAG   N/A
+COS_IN      PB13   input
 
-MDSTAR   PB14   output
-MDMR     PB8    output
-MYSF     PB9    output
-MP25     PB15   output
-MNXDN    N/A
-MPOCSAG  N/A
+DSTAR       N/A
+DMR         N/A
+YSF         N/A
+P25         N/A
+NXDN        N/A
+POCSAG      N/A
 
-RX       PB0    analog input
-RSSI     PB1    analog input
-TX       PA4    analog output
+MDMR/BIT0   PB8    output
+MYSF/BIT1   PB9    output
+MDSTAR/BIT2 PB14   output
+MP25/BIT3   PB15   output          Generic Mode Pins
+MNXDN       N/A
+MPOCSAG     N/A
 
-EXT_CLK  PA15   input
+RX          PA0    analog input
+RSSI        PA1    analog input
+TX          PA4    analog output
 
-UART1_TX PA9    output
-UART1_RX PA10   output
-UART2_TX PA2    output
-UART2_RX PA3    output
+EXT_CLK     PA15   input
+
+UART1_TX    PA9    output
+UART1_RX    PA10   output          Host Data Communication
+
+UART2_TX    PA2    output
+UART2_RX    PA3    output          Nextion Data Communication
+
+I2C1_SCL    PB6    output
+I2C1_SDA    PB7    output          OLED Data Communication as master
 
 */
 
@@ -124,13 +128,13 @@ UART2_RX PA3    output
 
 #define PIN_RX            GPIO_Pin_0
 #define PIN_RX_CH         ADC_Channel_0
-#define PORT_RX           GPIOB
-#define RCC_Per_RX        RCC_AHB1Periph_GPIOB
+#define PORT_RX           GPIOA
+#define RCC_Per_RX        RCC_AHB1Periph_GPIOA
 
 #define PIN_RSSI          GPIO_Pin_1
 #define PIN_RSSI_CH       ADC_Channel_1
-#define PORT_RSSI         GPIOB
-#define RCC_Per_RSSI      RCC_AHB1Periph_GPIOB
+#define PORT_RSSI         GPIOA
+#define RCC_Per_RSSI      RCC_AHB1Periph_GPIOA
 
 #define PIN_TX            GPIO_Pin_4
 #define PIN_TX_CH         DAC_Channel_1

pins/pins_f4_stm32eda.h

@@ -0,0 +1,108 @@
+/*
+ *   Copyright (C) 2019,2020 by BG5HHP
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef _PINS_F4_STM32EDA
+#define _PINS_F4_STM32EDA
+
+/*
+Pin definitions for STM32F4 STM32-DVM-MTR2K & STM32-DVM-MASTR3:
+
+COS      PB13   input
+PTT      PB12   output
+COSLED   PB4    output
+LED      PB3    output
+
+P25      PB8    output
+NXDN     PB9    output
+DSTAR    PB6    output
+DMR      PB5    output
+YSF      PB7    output
+POCSAG   PC10   output
+FM       PC11   output
+
+RX       PB0    analog input
+RSSI     PB1    analog input
+TX       PA4    analog output
+
+EXT_CLK  PA15   input
+*/
+
+#define PIN_COS           GPIO_Pin_13
+#define PORT_COS          GPIOB
+#define RCC_Per_COS       RCC_AHB1Periph_GPIOB
+
+
+#define PIN_PTT           GPIO_Pin_12
+#define PORT_PTT          GPIOB
+#define RCC_Per_PTT       RCC_AHB1Periph_GPIOB
+
+#define PIN_COSLED        GPIO_Pin_4
+#define PORT_COSLED       GPIOB
+#define RCC_Per_COSLED    RCC_AHB1Periph_GPIOB
+
+#define PIN_LED           GPIO_Pin_3
+#define PORT_LED          GPIOB
+#define RCC_Per_LED       RCC_AHB1Periph_GPIOB
+
+#define PIN_P25           GPIO_Pin_8
+#define PORT_P25          GPIOB
+#define RCC_Per_P25       RCC_AHB1Periph_GPIOB
+
+#define PIN_NXDN          GPIO_Pin_9
+#define PORT_NXDN         GPIOB
+#define RCC_Per_NXDN      RCC_AHB1Periph_GPIOB
+
+#define PIN_DSTAR         GPIO_Pin_6
+#define PORT_DSTAR        GPIOB
+#define RCC_Per_DSTAR     RCC_AHB1Periph_GPIOB
+
+#define PIN_DMR           GPIO_Pin_5
+#define PORT_DMR          GPIOB
+#define RCC_Per_DMR       RCC_AHB1Periph_GPIOB
+
+#define PIN_YSF           GPIO_Pin_7
+#define PORT_YSF          GPIOB
+#define RCC_Per_YSF       RCC_AHB1Periph_GPIOB
+
+#define PIN_POCSAG        GPIO_Pin_10
+#define PORT_POCSAG       GPIOC
+#define RCC_Per_POCSAG    RCC_AHB1Periph_GPIOC
+
+#define PIN_FM            GPIO_Pin_11
+#define PORT_FM           GPIOC
+#define RCC_Per_FM        RCC_AHB1Periph_GPIOC
+
+#define PIN_EXT_CLK       GPIO_Pin_15
+#define SRC_EXT_CLK       GPIO_PinSource15
+#define PORT_EXT_CLK      GPIOA
+
+#define PIN_RX            GPIO_Pin_0
+#define PIN_RX_CH         ADC_Channel_8
+#define PORT_RX           GPIOB
+#define RCC_Per_RX        RCC_AHB1Periph_GPIOB
+
+#define PIN_RSSI          GPIO_Pin_1
+#define PIN_RSSI_CH       ADC_Channel_9
+#define PORT_RSSI         GPIOB
+#define RCC_Per_RSSI      RCC_AHB1Periph_GPIOB
+
+#define PIN_TX            GPIO_Pin_4
+#define PIN_TX_CH         DAC_Channel_1
+
+#endif
+