100 lines
2.5 KiB
C++
100 lines
2.5 KiB
C++
/*
|
|
* Copyright (C) OpenTX
|
|
*
|
|
* Based on code named
|
|
* th9x - http://code.google.com/p/th9x
|
|
* er9x - http://code.google.com/p/er9x
|
|
* gruvin9x - http://code.google.com/p/gruvin9x
|
|
*
|
|
* License GPLv2: http://www.gnu.org/licenses/gpl-2.0.html
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
#include "opentx.h"
|
|
#include "sbus.h"
|
|
|
|
#define SBUS_FRAME_GAP_DELAY 1000 // 500uS
|
|
|
|
#define SBUS_START_BYTE 0x0F
|
|
#define SBUS_FLAGS_IDX 23
|
|
#define SBUS_FRAMELOST_BIT 2
|
|
#define SBUS_FAILSAFE_BIT 3
|
|
|
|
#define SBUS_CH_BITS 11
|
|
#define SBUS_CH_MASK ((1<<SBUS_CH_BITS)-1)
|
|
|
|
#define SBUS_CH_CENTER 0x3E0
|
|
|
|
uint8_t SbusFrame[SBUS_MAX_FRAME_SIZE];
|
|
uint16_t SbusTimer ;
|
|
uint8_t SbusIndex = 0 ;
|
|
|
|
// Range for pulses (ppm input) is [-512:+512]
|
|
void processSbusFrame(uint8_t * sbus, int16_t * pulses, uint32_t size)
|
|
{
|
|
uint32_t inputbitsavailable = 0;
|
|
uint32_t inputbits = 0;
|
|
|
|
if (sbus[0] != SBUS_START_BYTE) {
|
|
return; // not a valid SBUS frame
|
|
}
|
|
|
|
if (size < SBUS_MIN_FRAME_SIZE) {
|
|
return;
|
|
}
|
|
|
|
if (size > SBUS_FLAGS_IDX && ((sbus[SBUS_FLAGS_IDX] & (1<<SBUS_FAILSAFE_BIT)) || (sbus[SBUS_FLAGS_IDX] & (1<<SBUS_FRAMELOST_BIT)))) {
|
|
return; // SBUS invalid frame or failsafe mode
|
|
}
|
|
|
|
// Skip start byte
|
|
sbus++;
|
|
|
|
for (uint32_t i=0; i<NUM_TRAINER; i++) {
|
|
while (inputbitsavailable < SBUS_CH_BITS) {
|
|
inputbits |= *sbus++ << inputbitsavailable;
|
|
inputbitsavailable += 8;
|
|
}
|
|
*pulses++ = ((int32_t) (inputbits & SBUS_CH_MASK) - SBUS_CH_CENTER) * 5 / 8;
|
|
inputbitsavailable -= SBUS_CH_BITS;
|
|
inputbits >>= SBUS_CH_BITS;
|
|
}
|
|
|
|
ppmInputValidityTimer = PPM_IN_VALID_TIMEOUT;
|
|
}
|
|
|
|
void processSbusInput()
|
|
{
|
|
#if !defined(SIMU)
|
|
uint8_t rxchar;
|
|
uint32_t active = 0;
|
|
while (sbusGetByte(&rxchar)) {
|
|
active = 1;
|
|
SbusFrame[SbusIndex++] = rxchar;
|
|
if (SbusIndex > SBUS_MAX_FRAME_SIZE-1) {
|
|
SbusIndex = SBUS_MAX_FRAME_SIZE-1;
|
|
}
|
|
}
|
|
if (active) {
|
|
SbusTimer = getTmr2MHz();
|
|
return;
|
|
}
|
|
else {
|
|
if (SbusIndex) {
|
|
if ((uint16_t) (getTmr2MHz() - SbusTimer) > SBUS_FRAME_GAP_DELAY) {
|
|
processSbusFrame(SbusFrame, ppmInput, SbusIndex);
|
|
SbusIndex = 0;
|
|
}
|
|
}
|
|
}
|
|
#endif
|
|
}
|