mirror of https://github.com/g4klx/MMDVM.git
First version of the AX25 TX functionality.
This commit is contained in:
Jonathan Naylor
parent
7ad70d04a4
commit
3de10fe98b
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@ -0,0 +1,36 @@
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/*
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* Copyright (C) 2020 by Jonathan Naylor G4KLX
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#if !defined(AX25DEFINES_H)
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#define AX25DEFINES_H
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const uint8_t AX25_RADIO_SYMBOL_LENGTH = 20U; // At 24 kHz sample rate
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const uint8_t AX25_FRAME_START = 0x7EU;
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const uint8_t AX25_FRAME_END = 0x7EU;
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const uint8_t AX25_FRAME_ABORT = 0xFEU;
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const uint8_t AX25_MAX_ONES = 5U;
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const uint16_t AX25_MIN_FRAME_LENGTH = 17U; // Callsign (7) + Callsign (7) + Control (1) + Checksum (2)
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const uint16_t AX25_MAX_FRAME_LENGTH = 294U; // Callsign (7) + Callsign (7) + 3 Digipeaters (21) +
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// Control (1) + Data (256) + Checksum (2)
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#endif
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@ -20,6 +20,7 @@
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#include "Config.h"
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#include "Globals.h"
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#include "AX25Demodulator.h"
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#include "AX25Defines.h"
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const float32_t SAMPLE_RATE = 24000.0F;
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const float32_t SYMBOL_RATE = 1200.0F;
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@ -178,7 +179,7 @@ bool CAX25Demodulator::PLL(bool input)
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bool CAX25Demodulator::HDLC(bool b)
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{
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if (m_hdlcOnes == 5U) {
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if (m_hdlcOnes == AX25_MAX_ONES) {
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if (b) {
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// flag byte
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m_hdlcFlag = true;
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@ -203,8 +204,8 @@ bool CAX25Demodulator::HDLC(bool b)
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bool result = false;
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switch (m_hdlcBuffer) {
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case 0x7E:
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if (m_frame.m_length >= 17U) {
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case AX25_FRAME_END:
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if (m_frame.m_length >= AX25_MIN_FRAME_LENGTH) {
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result = m_frame.checkCRC();
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if (!result)
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m_frame.m_length = 0U;
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@ -216,7 +217,7 @@ bool CAX25Demodulator::HDLC(bool b)
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m_hdlcBits = 0U;
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break;
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case 0xFE:
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case AX25_FRAME_ABORT:
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// Frame aborted
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m_frame.m_length = 0U;
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m_hdlcState = AX25_IDLE;
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@ -54,6 +54,15 @@ const uint16_t CCITT_TABLE[] = {
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0xf78f,0xe606,0xd49d,0xc514,0xb1ab,0xa022,0x92b9,0x8330,
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0x7bc7,0x6a4e,0x58d5,0x495c,0x3de3,0x2c6a,0x1ef1,0x0f78 };
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CAX25Frame::CAX25Frame(const uint8_t* data, uint16_t length) :
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m_data(),
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m_length(0U),
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m_fcs(0U)
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{
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for (uint16_t i = 0U; i < length && i < (AX25_MAX_PACKET_LEN - 2U); i++)
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m_data[m_length++] = data[i];
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}
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CAX25Frame::CAX25Frame() :
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m_data(),
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m_length(0U),
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@ -92,3 +101,22 @@ bool CAX25Frame::checkCRC()
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}
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}
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void CAX25Frame::addCRC()
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{
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union {
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uint16_t crc16;
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uint8_t crc8[2U];
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};
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crc16 = 0xFFFFU;
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for (uint16_t i = 0U; i < m_length; i++)
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crc16 = uint16_t(crc8[1U]) ^ CCITT_TABLE[crc8[0U] ^ m_data[i]];
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crc16 = ~crc16;
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m_fcs = crc16;
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m_data[m_length++] = crc8[0U];
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m_data[m_length++] = crc8[1U];
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}
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@ -25,12 +25,15 @@ const uint16_t AX25_MAX_PACKET_LEN = 300U;
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class CAX25Frame {
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public:
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CAX25Frame(const uint8_t* data, uint16_t length);
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CAX25Frame();
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bool append(uint16_t c);
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bool checkCRC();
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void addCRC();
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uint8_t m_data[AX25_MAX_PACKET_LEN];
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uint16_t m_length;
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uint16_t m_fcs;
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134
AX25TX.cpp
134
AX25TX.cpp
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@ -20,30 +20,160 @@
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#include "Globals.h"
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#include "AX25TX.h"
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#include "AX25Defines.h"
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#include "AX25Frame.h"
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CAX25TX::CAX25TX()
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const uint8_t START_FLAG[] = { AX25_FRAME_START };
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const uint8_t END_FLAG[] = { AX25_FRAME_END };
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const uint8_t BIT_MASK_TABLE1[] = { 0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U };
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#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])
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#define READ_BIT1(p,i) (p[(i)>>3] & BIT_MASK_TABLE1[(i)&7])
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const uint8_t BIT_MASK_TABLE2[] = { 0x01U, 0x02U, 0x04U, 0x08U, 0x10U, 0x20U, 0x40U, 0x80U };
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#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])
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#define READ_BIT2(p,i) (p[(i)>>3] & BIT_MASK_TABLE2[(i)&7])
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const uint16_t AUDIO_TABLE_LEN = 120U;
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const q15_t AUDIO_TABLE_DATA[] = {
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0, 214, 428, 641, 851, 1060, 1265, 1468, 1666, 1859, 2048, 2230, 2407, 2577, 2740, 2896, 3043, 3182, 3313, 3434, 3546, 3649,
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3741, 3823, 3895, 3955, 4006, 4045, 4073, 4089, 4095, 4089, 4073, 4045, 4006, 3955, 3895, 3823, 3741, 3649, 3546, 3434, 3313,
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3182, 3043, 2896, 2740, 2577, 2407, 2230, 2048, 1859, 1666, 1468, 1265, 1060, 851, 641, 428, 214, 0, -214, -428, -641, -851,
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-1060, -1265, -1468, -1666, -1859, -2047, -2230, -2407, -2577, -2740, -2896, -3043, -3182, -3313, -3434, -3546, -3649, -3741,
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-3823, -3895, -3955, -4006, -4045, -4073, -4089, -4095, -4089, -4073, -4045, -4006, -3955, -3895, -3823, -3741, -3649, -3546,
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-3434, -3313, -3182, -3043, -2896, -2740, -2577, -2407, -2230, -2047, -1859, -1666, -1468, -1265, -1060, -851, -641, -428, -214
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};
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CAX25TX::CAX25TX() :
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m_twist(-6),
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m_poBuffer(),
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m_poLen(0U),
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m_poPtr(0U),
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m_txDelay(120U),
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m_tablePtr(0U),
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m_nrzi(false)
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{
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}
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void CAX25TX::process()
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{
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if (m_poLen == 0U)
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return;
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uint16_t space = io.getSpace();
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while (space > AX25_RADIO_SYMBOL_LENGTH) {
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bool b = READ_BIT1(m_poBuffer, m_poPtr) != 0U;
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m_poPtr++;
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writeBit(b);
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space -= AX25_RADIO_SYMBOL_LENGTH;
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if (m_poPtr >= m_poLen) {
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m_poPtr = 0U;
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m_poLen = 0U;
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return;
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}
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}
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}
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uint8_t CAX25TX::writeData(const uint8_t* data, uint16_t length)
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{
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CAX25Frame frame(data, length);
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frame.addCRC();
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m_poLen = 0U;
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m_poPtr = 0U;
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m_nrzi = false;
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m_tablePtr = 0U;
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// Add TX delay (already NRZI)
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for (uint16_t i = 0U; i < m_txDelay; i++, m_poLen++)
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WRITE_BIT1(m_poBuffer, m_poLen, false);
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// Add the Start Flag
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for (uint16_t i = 0U; i < 8U; i++, m_poLen++) {
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bool b1 = READ_BIT1(START_FLAG, i) != 0U;
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bool b2 = NRZI(b1);
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WRITE_BIT1(m_poBuffer, m_poLen, b2);
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}
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uint8_t ones = 0U;
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for (uint16_t i = 0U; i < (frame.m_length * 8U); i++) {
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bool b1 = READ_BIT2(START_FLAG, i) != 0U;
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bool b2 = NRZI(b1);
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WRITE_BIT1(m_poBuffer, m_poLen, b2);
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m_poLen++;
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if (b1) {
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ones++;
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if (ones == AX25_MAX_ONES) {
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bool b = NRZI(false);
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WRITE_BIT1(m_poBuffer, m_poLen, b);
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m_poLen++;
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ones = 0U;
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}
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} else {
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ones = 0U;
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}
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}
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// Add the End Flag
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for (uint16_t i = 0U; i < 8U; i++, m_poLen++) {
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bool b1 = READ_BIT1(END_FLAG, i) != 0U;
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bool b2 = NRZI(b1);
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WRITE_BIT1(m_poBuffer, m_poLen, b2);
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}
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return 0U;
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}
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void CAX25TX::writeBit(bool b)
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{
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q15_t in[AX25_RADIO_SYMBOL_LENGTH];
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for (uint8_t i = 0U; i < AX25_RADIO_SYMBOL_LENGTH; i++) {
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in[i] = AUDIO_TABLE_DATA[m_tablePtr];
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if (b)
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m_tablePtr += 6U;
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else
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m_tablePtr += 11U;
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if (m_tablePtr >= AUDIO_TABLE_LEN)
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m_tablePtr -= AUDIO_TABLE_LEN;
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}
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q15_t out[AX25_RADIO_SYMBOL_LENGTH];
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m_twist.process(in, out, AX25_RADIO_SYMBOL_LENGTH);
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io.write(STATE_AX25, out, AX25_RADIO_SYMBOL_LENGTH);
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}
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void CAX25TX::setParams(int8_t twist)
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{
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m_twist.setTwist(twist);
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}
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void CAX25TX::setTXDelay(uint8_t delay)
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{
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m_txDelay = delay * 12U;
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}
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uint8_t CAX25TX::getSpace() const
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{
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return 0U;
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return m_poLen == 0U ? 255U : 0U;
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}
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bool CAX25TX::NRZI(bool b)
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{
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bool result = (b == m_nrzi);
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m_nrzi = b;
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return result;
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}
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12
AX25TX.h
12
AX25TX.h
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@ -21,7 +21,7 @@
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#include "Config.h"
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#include "SerialRB.h"
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#include "AX25Twist.h"
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class CAX25TX {
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public:
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@ -38,6 +38,16 @@ public:
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uint8_t getSpace() const;
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private:
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CAX25Twist m_twist;
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uint8_t m_poBuffer[560U];
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uint16_t m_poLen;
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uint16_t m_poPtr;
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uint16_t m_txDelay;
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uint16_t m_tablePtr;
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bool m_nrzi;
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void writeBit(bool b);
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bool NRZI(bool b);
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};
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#endif
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