135 lines
5.4 KiB
C++
135 lines
5.4 KiB
C++
#include "Arduino.h"
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#include "variables.h"
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#define SBUS_MIN_OFFSET 173
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#define SBUS_MID_OFFSET 992
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#define SBUS_MAX_OFFSET 1811
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#define SBUS_CHANNEL_NUMBER 16
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#define SBUS_PACKET_LENGTH 25
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#define SBUS_FRAME_HEADER 0x0f
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#define SBUS_FRAME_FOOTER 0x00
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#define SBUS_FRAME_FOOTER_V2 0x04
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#define SBUS_STATE_FAILSAFE 0x08
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#define SBUS_STATE_SIGNALLOSS 0x04
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#define SBUS_IS_RECEIVING_THRESHOLD 250 //If there is no SBUS input for 250ms, assume connection is broken
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/*
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Precomputed mapping from 990-2010 to 173:1811
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equivalent to
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map(channels[i], RC_CHANNEL_MIN, RC_CHANNEL_MAX, SBUS_MIN_OFFSET, SBUS_MAX_OFFSET);
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*/
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int mapChannelToSbus(int in) {
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return (((long) in * 1605l) / 1000l) - 1417;
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}
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int mapSbusToChannel(int in) {
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//TODO, speed up this processing
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return map(in, 173, 1811, 990, 2010);
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}
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void sbusPreparePacket(uint8_t packet[], int channels[], bool isSignalLoss, bool isFailsafe){
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static int output[SBUS_CHANNEL_NUMBER] = {0};
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/*
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* Map 1000-2000 with middle at 1500 chanel values to
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* 173-1811 with middle at 992 S.BUS protocol requires
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*/
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for (uint8_t i = 0; i < SBUS_CHANNEL_NUMBER; i++) {
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output[i] = mapChannelToSbus(channels[i]);
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}
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uint8_t stateByte = 0x00;
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if (isSignalLoss) {
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stateByte |= SBUS_STATE_SIGNALLOSS;
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}
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if (isFailsafe) {
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stateByte |= SBUS_STATE_FAILSAFE;
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}
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packet[0] = SBUS_FRAME_HEADER; //Header
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packet[1] = (uint8_t) (output[0] & 0x07FF);
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packet[2] = (uint8_t) ((output[0] & 0x07FF)>>8 | (output[1] & 0x07FF)<<3);
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packet[3] = (uint8_t) ((output[1] & 0x07FF)>>5 | (output[2] & 0x07FF)<<6);
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packet[4] = (uint8_t) ((output[2] & 0x07FF)>>2);
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packet[5] = (uint8_t) ((output[2] & 0x07FF)>>10 | (output[3] & 0x07FF)<<1);
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packet[6] = (uint8_t) ((output[3] & 0x07FF)>>7 | (output[4] & 0x07FF)<<4);
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packet[7] = (uint8_t) ((output[4] & 0x07FF)>>4 | (output[5] & 0x07FF)<<7);
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packet[8] = (uint8_t) ((output[5] & 0x07FF)>>1);
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packet[9] = (uint8_t) ((output[5] & 0x07FF)>>9 | (output[6] & 0x07FF)<<2);
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packet[10] = (uint8_t) ((output[6] & 0x07FF)>>6 | (output[7] & 0x07FF)<<5);
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packet[11] = (uint8_t) ((output[7] & 0x07FF)>>3);
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packet[12] = (uint8_t) ((output[8] & 0x07FF));
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packet[13] = (uint8_t) ((output[8] & 0x07FF)>>8 | (output[9] & 0x07FF)<<3);
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packet[14] = (uint8_t) ((output[9] & 0x07FF)>>5 | (output[10] & 0x07FF)<<6);
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packet[15] = (uint8_t) ((output[10] & 0x07FF)>>2);
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packet[16] = (uint8_t) ((output[10] & 0x07FF)>>10 | (output[11] & 0x07FF)<<1);
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packet[17] = (uint8_t) ((output[11] & 0x07FF)>>7 | (output[12] & 0x07FF)<<4);
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packet[18] = (uint8_t) ((output[12] & 0x07FF)>>4 | (output[13] & 0x07FF)<<7);
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packet[19] = (uint8_t) ((output[13] & 0x07FF)>>1);
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packet[20] = (uint8_t) ((output[13] & 0x07FF)>>9 | (output[14] & 0x07FF)<<2);
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packet[21] = (uint8_t) ((output[14] & 0x07FF)>>6 | (output[15] & 0x07FF)<<5);
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packet[22] = (uint8_t) ((output[15] & 0x07FF)>>3);
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packet[23] = stateByte; //Flags byte
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packet[24] = SBUS_FRAME_FOOTER; //Footer
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}
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void sbusRead(HardwareSerial &_serial, SbusInput_t *sbusInput) {
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static byte buffer[25];
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static byte buffer_index = 0;
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static uint32_t _decoderErrorFrames;
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static uint32_t _goodFrames;
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while (_serial.available()) {
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byte rx = _serial.read();
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if (buffer_index == 0 && rx != SBUS_FRAME_HEADER) {
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//incorrect start byte, out of sync
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_decoderErrorFrames++;
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continue;
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}
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buffer[buffer_index] = rx;
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buffer_index++;
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if (buffer_index == 25) {
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buffer_index = 0;
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if (buffer[24] != SBUS_FRAME_FOOTER) {
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//incorrect end byte, out of sync
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_decoderErrorFrames++;
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continue;
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}
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_goodFrames++;
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sbusInput->channels[0] = ((buffer[1] |buffer[2]<<8) & 0x07FF);
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sbusInput->channels[1] = ((buffer[2]>>3 |buffer[3]<<5) & 0x07FF);
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sbusInput->channels[2] = ((buffer[3]>>6 |buffer[4]<<2 |buffer[5]<<10) & 0x07FF);
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sbusInput->channels[3] = ((buffer[5]>>1 |buffer[6]<<7) & 0x07FF);
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sbusInput->channels[4] = ((buffer[6]>>4 |buffer[7]<<4) & 0x07FF);
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sbusInput->channels[5] = ((buffer[7]>>7 |buffer[8]<<1 |buffer[9]<<9) & 0x07FF);
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sbusInput->channels[6] = ((buffer[9]>>2 |buffer[10]<<6) & 0x07FF);
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sbusInput->channels[7] = ((buffer[10]>>5|buffer[11]<<3) & 0x07FF);
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sbusInput->channels[8] = ((buffer[12] |buffer[13]<<8) & 0x07FF);
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sbusInput->channels[9] = ((buffer[13]>>3|buffer[14]<<5) & 0x07FF);
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sbusInput->channels[10] = ((buffer[14]>>6|buffer[15]<<2|buffer[16]<<10) & 0x07FF);
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sbusInput->channels[11] = ((buffer[16]>>1|buffer[17]<<7) & 0x07FF);
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sbusInput->channels[12] = ((buffer[17]>>4|buffer[18]<<4) & 0x07FF);
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sbusInput->channels[13] = ((buffer[18]>>7|buffer[19]<<1|buffer[20]<<9) & 0x07FF);
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sbusInput->channels[14] = ((buffer[20]>>2|buffer[21]<<6) & 0x07FF);
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sbusInput->channels[15] = ((buffer[21]>>5|buffer[22]<<3) & 0x07FF);
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for (uint8_t channelIndex = 0; channelIndex < SBUS_CHANNEL_NUMBER; channelIndex++) {
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sbusInput->channels[channelIndex] = mapSbusToChannel(sbusInput->channels[channelIndex]);
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}
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sbusInput->lastChannelReceivedAt = millis();
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}
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}
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}
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bool isReceivingSbus(SbusInput_t *sbusInput) {
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return !(millis() - sbusInput->lastChannelReceivedAt > SBUS_IS_RECEIVING_THRESHOLD);
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} |