132 lines
3.4 KiB
C++
132 lines
3.4 KiB
C++
/*
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* Copyright (C) EdgeTX
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*
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* Based on code named
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* opentx - https://github.com/opentx/opentx
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* th9x - http://code.google.com/p/th9x
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* er9x - http://code.google.com/p/er9x
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* gruvin9x - http://code.google.com/p/gruvin9x
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*
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* License GPLv2: http://www.gnu.org/licenses/gpl-2.0.html
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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 version 2 as
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* published by the Free Software Foundation.
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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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#include "opentx.h"
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#include "sbus.h"
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#include "timers_driver.h"
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#define SBUS_FRAME_GAP_DELAY 1000 // 500uS
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#define SBUS_START_BYTE 0x0F
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#define SBUS_END_BYTE 0x00
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#define SBUS_FLAGS_IDX 23
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#define SBUS_FRAMELOST_BIT 2
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#define SBUS_FAILSAFE_BIT 3
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#define SBUS_CH_BITS 11
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#define SBUS_CH_MASK ((1<<SBUS_CH_BITS) - 1)
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#define SBUS_CH_CENTER 0x3E0
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static int (*_sbusAuxGetByte)(void*, uint8_t*) = nullptr;
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static void* _sbusAuxGetByteCtx = nullptr;
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void sbusSetAuxGetByte(void* ctx, int (*fct)(void*, uint8_t*))
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{
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_sbusAuxGetByte = nullptr;
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_sbusAuxGetByteCtx = ctx;
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_sbusAuxGetByte = fct;
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}
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int sbusAuxGetByte(uint8_t* byte)
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{
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auto _getByte = _sbusAuxGetByte;
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auto _ctx = _sbusAuxGetByteCtx;
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if (_getByte) {
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return _getByte(_ctx, byte);
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}
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return -1;
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}
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static int (*sbusGetByte)(uint8_t*) = nullptr;
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void sbusSetGetByte(int (*fct)(uint8_t*))
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{
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sbusGetByte = fct;
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}
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// Range for pulses (ppm input) is [-512:+512]
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void processSbusFrame(uint8_t * sbus, int16_t * pulses, uint32_t size)
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{
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if (size != SBUS_FRAME_SIZE || sbus[0] != SBUS_START_BYTE ||
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sbus[SBUS_FRAME_SIZE - 1] != SBUS_END_BYTE) {
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return; // not a valid SBUS frame
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}
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if ((sbus[SBUS_FLAGS_IDX] & (1 << SBUS_FAILSAFE_BIT)) ||
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(sbus[SBUS_FLAGS_IDX] & (1 << SBUS_FRAMELOST_BIT))) {
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return; // SBUS invalid frame or failsafe mode
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}
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sbus++; // skip start byte
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uint32_t inputbitsavailable = 0;
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uint32_t inputbits = 0;
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for (uint32_t i=0; i<MAX_TRAINER_CHANNELS; i++) {
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while (inputbitsavailable < SBUS_CH_BITS) {
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inputbits |= *sbus++ << inputbitsavailable;
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inputbitsavailable += 8;
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}
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*pulses++ = ((int32_t) (inputbits & SBUS_CH_MASK) - SBUS_CH_CENTER) * 5 / 8;
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inputbitsavailable -= SBUS_CH_BITS;
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inputbits >>= SBUS_CH_BITS;
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}
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ppmInputValidityTimer = PPM_IN_VALID_TIMEOUT;
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}
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void processSbusInput()
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{
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// TODO: place this outside of the function
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static uint8_t SbusIndex = 0;
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static uint16_t SbusTimer;
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static uint8_t SbusFrame[SBUS_FRAME_SIZE];
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uint32_t active = 0;
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// Drain input first (if existing)
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uint8_t rxchar;
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auto _getByte = sbusGetByte;
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while (_getByte && (_getByte(&rxchar) > 0)) {
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active = 1;
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if (SbusIndex > SBUS_FRAME_SIZE - 1) {
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SbusIndex = SBUS_FRAME_SIZE - 1;
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}
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SbusFrame[SbusIndex++] = rxchar;
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}
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// Data has been received
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if (active) {
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SbusTimer = getTmr2MHz();
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return;
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}
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// Check if end-of-frame is detected
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if (SbusIndex) {
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if ((uint16_t)(getTmr2MHz() - SbusTimer) > SBUS_FRAME_GAP_DELAY) {
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processSbusFrame(SbusFrame, ppmInput, SbusIndex);
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SbusIndex = 0;
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}
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}
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}
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