Buffer output after adding some initial silence.

FM.cpp

@@ -44,12 +44,13 @@ m_blanking(),
 m_useCOS(true),
 m_cosInvert(false),
 m_rfAudioBoost(1U),
-m_downsampler(128),//Size might need adjustement
+m_downsampler(128U),//Size might need adjustement
-m_rxLevel(1)
+m_rxLevel(1),
+m_outputRB(2400U)   // 100ms of audio
 {
 }
 
-void CFM::samples(bool cos, q15_t* samples, uint8_t length)
+void CFM::samples(bool cos, const q15_t* samples, uint8_t length)
 {
   if (m_useCOS) {
     if (m_cosInvert)
@@ -115,15 +116,32 @@ void CFM::samples(bool cos, q15_t* samples, uint8_t length)
 
     currentSample += m_ctcssTX.getAudio();
 
-    samples[i] = currentSample;
+    if (m_modemState == STATE_FM)
+      m_outputRB.put(currentSample);
   }
-
-  if (m_modemState == STATE_FM)
-    io.write(STATE_FM, samples, i);//only write the actual number of processed samples to IO
 }
 
 void CFM::process()
 {
+  if (m_modemState != STATE_FM)
+    return;
+
+  uint16_t length = m_outputRB.getData();
+  if (length == 0U)
+    return;
+
+  uint16_t space = io.getSpace();
+  if (space == 0U)
+    return;
+
+  if (space < length)
+    length = space;
+
+  for (uint16_t i = 0U; i < length; i++) {
+    q15_t sample;
+    m_outputRB.get(sample);
+    io.write(STATE_FM, &sample, 1U);
+  }
 }
 
 void CFM::reset()
@@ -141,6 +159,8 @@ void CFM::reset()
   m_rfAck.stop();
   m_callsign.stop();
   m_timeoutTone.stop();
+
+  m_outputRB.reset();
 }
 
 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)
@@ -263,6 +283,8 @@ void CFM::listeningState(bool validSignal)
         sendCallsign();
     }
 
+    insertSilence(50U);
+
     beginRelaying();
 
     m_callsignTimer.start();
@@ -438,3 +460,10 @@ void CFM::beginRelaying()
   m_ackMinTimer.start();
 }
 
+void CFM::insertSilence(uint16_t ms)
+{
+  uint32_t nSamples = ms * 24U;
+
+  for (uint32_t i = 0U; i < nSamples; i++)
+    m_outputRB.put(0);
+}

FM.h

@@ -27,6 +27,7 @@
 #include "FMTimeout.h"
 #include "FMKeyer.h"
 #include "FMTimer.h"
+#include "FMRB.h"
 #include "FMDirectForm1.h"
 #include "FMDownsampler.h"
 
@@ -47,7 +48,7 @@ class CFM {
 public:
   CFM();
 
-  void samples(bool cos, q15_t* samples, uint8_t length);
+  void samples(bool cos, const q15_t* samples, uint8_t length);
 
   void process();
 
@@ -83,6 +84,7 @@ private:
   q15_t                m_rfAudioBoost;
   CFMDownsampler       m_downsampler;
   q15_t                m_rxLevel;
+  CFMRB                m_outputRB;
 
   void stateMachine(bool validSignal);
   void listeningState(bool validSignal);
@@ -97,6 +99,7 @@ private:
 
   void sendCallsign();
   void beginRelaying();
+  void insertSilence(uint16_t ms);
 };
 
 #endif

FMDownsampleRB.h

@@ -16,8 +16,8 @@
  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
-#if !defined(FMRB_H)
+#if !defined(FMDOWNSAMPLERB_H)
-#define  FMRB_H
+#define  FMDOWNSAMPLERB_H
 
 #if defined(STM32F4XX)
 #include "stm32f4xx.h"

FMRB.cpp

@@ -0,0 +1,110 @@
+/*
+TX fifo control - Copyright (C) KI6ZUM 2015
+Copyright (C) 2015,2016,2020 by Jonathan Naylor G4KLX
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public
+License as published by the Free Software Foundation; either
+version 2 of the License, or (at your option) any later version.
+
+This library 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with this library; if not, write to the
+Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+Boston, MA  02110-1301, USA.
+*/
+
+#include "FMRB.h"
+
+CFMRB::CFMRB(uint16_t length) :
+m_length(length),
+m_head(0U),
+m_tail(0U),
+m_full(false),
+m_overflow(false)
+{
+  m_samples = new q15_t[length];
+}
+
+uint16_t CFMRB::getSpace() const
+{
+  uint16_t n = 0U;
+
+  if (m_tail == m_head)
+    n = m_full ? 0U : m_length;
+  else if (m_tail < m_head)
+    n = m_length - m_head + m_tail;
+  else
+    n = m_tail - m_head;
+
+  if (n > m_length)
+    n = 0U;
+
+  return n;
+}
+
+uint16_t CFMRB::getData() const
+{
+  if (m_tail == m_head)
+    return m_full ? m_length : 0U;
+  else if (m_tail < m_head)
+    return m_head - m_tail;
+  else
+    return m_length - m_tail + m_head;
+}
+
+bool CFMRB::put(q15_t sample)
+{
+  if (m_full) {
+    m_overflow = true;
+    return false;
+  }
+
+  m_samples[m_head] = sample;
+
+  m_head++;
+  if (m_head >= m_length)
+    m_head = 0U;
+
+  if (m_head == m_tail)
+    m_full = true;
+
+  return true;
+}
+
+bool CFMRB::get(q15_t& sample)
+{
+  if (m_head == m_tail && !m_full)
+    return false;
+
+  sample = m_samples[m_tail];
+
+  m_full = false;
+
+  m_tail++;
+  if (m_tail >= m_length)
+    m_tail = 0U;
+
+  return true;
+}
+
+bool CFMRB::hasOverflowed()
+{
+  bool overflow = m_overflow;
+
+  m_overflow = false;
+
+  return overflow;
+}
+
+void CFMRB::reset()
+{
+  m_head = 0U;
+  m_tail = 0U;
+  m_full     = false;
+  m_overflow = false;
+}

FMRB.h

@@ -0,0 +1,72 @@
+/*
+Serial fifo control - Copyright (C) KI6ZUM 2015
+Copyright (C) 2015,2016,2020 by Jonathan Naylor G4KLX
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public
+License as published by the Free Software Foundation; either
+version 2 of the License, or (at your option) any later version.
+
+This library 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with this library; if not, write to the
+Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+Boston, MA  02110-1301, USA.
+*/
+
+#if !defined(FMRB_H)
+#define  FMRB_H
+
+#if defined(STM32F4XX)
+#include "stm32f4xx.h"
+#elif defined(STM32F7XX)
+#include "stm32f7xx.h"
+#elif defined(STM32F105xC)
+#include "stm32f1xx.h"
+#include <cstddef>
+#else
+#include <Arduino.h>
+#endif
+
+#if defined(__SAM3X8E__) || defined(STM32F105xC)
+#define  ARM_MATH_CM3
+#elif defined(STM32F7XX)
+#define  ARM_MATH_CM7
+#elif defined(STM32F4XX) || defined(__MK20DX256__) || defined(__MK64FX512__) || defined(__MK66FX1M0__)
+#define  ARM_MATH_CM4
+#else
+#error "Unknown processor type"
+#endif
+
+#include <arm_math.h>
+
+class CFMRB {
+public:
+  CFMRB(uint16_t length);
+  
+  uint16_t getSpace() const;
+  
+  uint16_t getData() const;
+
+  bool put(q15_t sample);
+
+  bool get(q15_t& sample);
+
+  bool hasOverflowed();
+
+  void reset();
+
+private:
+  uint16_t          m_length;
+  volatile q15_t*   m_samples;
+  volatile uint16_t m_head;
+  volatile uint16_t m_tail;
+  volatile bool     m_full;
+  bool              m_overflow;
+};
+
+#endif

SerialPort.cpp

@@ -101,7 +101,7 @@ const uint8_t MMDVM_DEBUG5       = 0xF5U;
 #define	HW_TYPE	"MMDVM"
 #endif
 
-#define DESCRIPTION "20200506 (D-Star/DMR/System Fusion/P25/NXDN/POCSAG/FM)"
+#define DESCRIPTION "20200508 (D-Star/DMR/System Fusion/P25/NXDN/POCSAG/FM)"
 
 #if defined(GITVERSION)
 #define concat(h, a, b, c) h " " a " " b " GitID #" c ""