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AP_Frsky_Telem: prevent SPort frame fragmentation by writing whole 8byte frames vs writing single bytes

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general scheduler delays could introduce small delays when writing SPort frames to the uart one byte
at the time potentially leading to rx desyncs on the SPort bus.
This fix replaces single byte writes with full frame writes.

The library has around 10ms to repond to polling so to guarantee frame integrity responses taking
longer than 7500us are discarded
This commit is contained in:
yaapu 2020-05-10 00:15:49 +02:00 committed by Andrew Tridgell
parent af80c4a29f
commit 6303c700d4
2 changed files with 92 additions and 91 deletions
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155
libraries/AP_Frsky_Telem/AP_Frsky_Telem.cpp
View File

@ -148,15 +148,15 @@ void AP_Frsky_Telem::process_packet(uint8_t idx)
switch (idx) {
case TEXT: // 0x5000 status text
if (get_next_msg_chunk()) {
send_uint32(SPORT_DATA_FRAME, DIY_FIRST_ID, _msg_chunk.chunk);
send_sport_frame(SPORT_DATA_FRAME, DIY_FIRST_ID, _msg_chunk.chunk);
}
break;
case ATTITUDE: // 0x5006 Attitude and range
send_uint32(SPORT_DATA_FRAME, DIY_FIRST_ID+6, calc_attiandrng());
send_sport_frame(SPORT_DATA_FRAME, DIY_FIRST_ID+6, calc_attiandrng());
break;
case GPS_LAT: // 0x800 GPS lat
// sample both lat and lon at the same time
send_uint32(SPORT_DATA_FRAME, GPS_LONG_LATI_FIRST_ID, calc_gps_latlng(&_passthrough.send_latitude)); // gps latitude or longitude
send_sport_frame(SPORT_DATA_FRAME, GPS_LONG_LATI_FIRST_ID, calc_gps_latlng(&_passthrough.send_latitude)); // gps latitude or longitude
_passthrough.gps_lng_sample = calc_gps_latlng(&_passthrough.send_latitude);
// force the scheduler to select GPS lon as packet that's been waiting the most
// this guarantees that gps coords are sent at max
@ -164,28 +164,28 @@ void AP_Frsky_Telem::process_packet(uint8_t idx)
_scheduler.packet_timer[GPS_LON] = _scheduler.packet_timer[GPS_LAT] - 10000;
break;
case GPS_LON: // 0x800 GPS lon
send_uint32(SPORT_DATA_FRAME, GPS_LONG_LATI_FIRST_ID, _passthrough.gps_lng_sample); // gps longitude
send_sport_frame(SPORT_DATA_FRAME, GPS_LONG_LATI_FIRST_ID, _passthrough.gps_lng_sample); // gps longitude
break;
case VEL_YAW: // 0x5005 Vel and Yaw
send_uint32(SPORT_DATA_FRAME, DIY_FIRST_ID+5, calc_velandyaw());
send_sport_frame(SPORT_DATA_FRAME, DIY_FIRST_ID+5, calc_velandyaw());
break;
case AP_STATUS: // 0x5001 AP status
send_uint32(SPORT_DATA_FRAME, DIY_FIRST_ID+1, calc_ap_status());
send_sport_frame(SPORT_DATA_FRAME, DIY_FIRST_ID+1, calc_ap_status());
break;
case GPS_STATUS: // 0x5002 GPS Status
send_uint32(SPORT_DATA_FRAME, DIY_FIRST_ID+2, calc_gps_status());
send_sport_frame(SPORT_DATA_FRAME, DIY_FIRST_ID+2, calc_gps_status());
break;
case HOME: // 0x5004 Home
send_uint32(SPORT_DATA_FRAME, DIY_FIRST_ID+4, calc_home());
send_sport_frame(SPORT_DATA_FRAME, DIY_FIRST_ID+4, calc_home());
break;
case BATT_2: // 0x5008 Battery 2 status
send_uint32(SPORT_DATA_FRAME, DIY_FIRST_ID+8, calc_batt(1));
send_sport_frame(SPORT_DATA_FRAME, DIY_FIRST_ID+8, calc_batt(1));
break;
case BATT_1: // 0x5003 Battery 1 status
send_uint32(SPORT_DATA_FRAME, DIY_FIRST_ID+3, calc_batt(0));
send_sport_frame(SPORT_DATA_FRAME, DIY_FIRST_ID+3, calc_batt(0));
break;
case PARAM: // 0x5007 parameters
send_uint32(SPORT_DATA_FRAME, DIY_FIRST_ID+7, calc_param());
send_sport_frame(SPORT_DATA_FRAME, DIY_FIRST_ID+7, calc_param());
break;
}
}
@ -214,8 +214,8 @@ void AP_Frsky_Telem::send_SPort_Passthrough(void)
prev_byte = _passthrough.new_byte;
_passthrough.new_byte = _port->read();
}
if (prev_byte == START_STOP_SPORT) {
if (_passthrough.new_byte == SENSOR_ID_28) { // byte 0x7E is the header of each poll request
if (prev_byte == FRAME_HEAD) {
if (_passthrough.new_byte == SENSOR_ID_27) { // byte 0x7E is the header of each poll request
run_wfq_scheduler();
}
}
@ -256,7 +256,7 @@ void AP_Frsky_Telem::send_SPort(void)
for (int16_t i = 0; i < numc; i++) {
int16_t readbyte = _port->read();
if (_SPort.sport_status == false) {
if (readbyte == START_STOP_SPORT) {
if (readbyte == FRAME_HEAD) {
_SPort.sport_status = true;
}
} else {
@ -265,13 +265,13 @@ void AP_Frsky_Telem::send_SPort(void)
case SENSOR_ID_VARIO: // Sensor ID 0
switch (_SPort.vario_call) {
case 0:
send_uint32(SPORT_DATA_FRAME, DATA_ID_BARO_ALT_BP, _SPort_data.alt_nav_meters); // send altitude integer part
send_sport_frame(SPORT_DATA_FRAME, DATA_ID_BARO_ALT_BP, _SPort_data.alt_nav_meters); // send altitude integer part
break;
case 1:
send_uint32(SPORT_DATA_FRAME, DATA_ID_BARO_ALT_AP, _SPort_data.alt_nav_cm); // send altitude decimal part
send_sport_frame(SPORT_DATA_FRAME, DATA_ID_BARO_ALT_AP, _SPort_data.alt_nav_cm); // send altitude decimal part
break;
case 2:
send_uint32(SPORT_DATA_FRAME, DATA_ID_VARIO, _SPort_data.vario_vspd); // send vspeed m/s
send_sport_frame(SPORT_DATA_FRAME, DATA_ID_VARIO, _SPort_data.vario_vspd); // send vspeed m/s
_SPort.vario_refresh = true;
break;
}
@ -282,10 +282,10 @@ void AP_Frsky_Telem::send_SPort(void)
case SENSOR_ID_FAS: // Sensor ID 2
switch (_SPort.fas_call) {
case 0:
send_uint32(SPORT_DATA_FRAME, DATA_ID_FUEL, (uint16_t)roundf(_battery.capacity_remaining_pct())); // send battery remaining
send_sport_frame(SPORT_DATA_FRAME, DATA_ID_FUEL, (uint16_t)roundf(_battery.capacity_remaining_pct())); // send battery remaining
break;
case 1:
send_uint32(SPORT_DATA_FRAME, DATA_ID_VFAS, (uint16_t)roundf(_battery.voltage() * 10.0f)); // send battery voltage
send_sport_frame(SPORT_DATA_FRAME, DATA_ID_VFAS, (uint16_t)roundf(_battery.voltage() * 10.0f)); // send battery voltage
break;
case 2:
{
@ -293,7 +293,7 @@ void AP_Frsky_Telem::send_SPort(void)
if (!_battery.current_amps(current)) {
current = 0;
}
send_uint32(SPORT_DATA_FRAME, DATA_ID_CURRENT, (uint16_t)roundf(current * 10.0f)); // send current consumption
send_sport_frame(SPORT_DATA_FRAME, DATA_ID_CURRENT, (uint16_t)roundf(current * 10.0f)); // send current consumption
break;
}
break;
@ -305,25 +305,25 @@ void AP_Frsky_Telem::send_SPort(void)
case SENSOR_ID_GPS: // Sensor ID 3
switch (_SPort.gps_call) {
case 0:
send_uint32(SPORT_DATA_FRAME, GPS_LONG_LATI_FIRST_ID, calc_gps_latlng(&_passthrough.send_latitude)); // gps latitude or longitude
send_sport_frame(SPORT_DATA_FRAME, GPS_LONG_LATI_FIRST_ID, calc_gps_latlng(&_passthrough.send_latitude)); // gps latitude or longitude
break;
case 1:
send_uint32(SPORT_DATA_FRAME, GPS_LONG_LATI_FIRST_ID, calc_gps_latlng(&_passthrough.send_latitude)); // gps latitude or longitude
send_sport_frame(SPORT_DATA_FRAME, GPS_LONG_LATI_FIRST_ID, calc_gps_latlng(&_passthrough.send_latitude)); // gps latitude or longitude
break;
case 2:
send_uint32(SPORT_DATA_FRAME, DATA_ID_GPS_SPEED_BP, _SPort_data.speed_in_meter); // send gps speed integer part
send_sport_frame(SPORT_DATA_FRAME, DATA_ID_GPS_SPEED_BP, _SPort_data.speed_in_meter); // send gps speed integer part
break;
case 3:
send_uint32(SPORT_DATA_FRAME, DATA_ID_GPS_SPEED_AP, _SPort_data.speed_in_centimeter); // send gps speed decimal part
send_sport_frame(SPORT_DATA_FRAME, DATA_ID_GPS_SPEED_AP, _SPort_data.speed_in_centimeter); // send gps speed decimal part
break;
case 4:
send_uint32(SPORT_DATA_FRAME, DATA_ID_GPS_ALT_BP, _SPort_data.alt_gps_meters); // send gps altitude integer part
send_sport_frame(SPORT_DATA_FRAME, DATA_ID_GPS_ALT_BP, _SPort_data.alt_gps_meters); // send gps altitude integer part
break;
case 5:
send_uint32(SPORT_DATA_FRAME, DATA_ID_GPS_ALT_AP, _SPort_data.alt_gps_cm); // send gps altitude decimals
send_sport_frame(SPORT_DATA_FRAME, DATA_ID_GPS_ALT_AP, _SPort_data.alt_gps_cm); // send gps altitude decimals
break;
case 6:
send_uint32(SPORT_DATA_FRAME, DATA_ID_GPS_COURS_BP, _SPort_data.yaw); // send heading in degree based on AHRS and not GPS
send_sport_frame(SPORT_DATA_FRAME, DATA_ID_GPS_COURS_BP, _SPort_data.yaw); // send heading in degree based on AHRS and not GPS
_SPort.gps_refresh = true;
break;
}
@ -334,10 +334,10 @@ void AP_Frsky_Telem::send_SPort(void)
case SENSOR_ID_SP2UR: // Sensor ID 6
switch (_SPort.various_call) {
case 0 :
send_uint32(SPORT_DATA_FRAME, DATA_ID_TEMP2, (uint16_t)(AP::gps().num_sats() * 10 + AP::gps().status())); // send GPS status and number of satellites as num_sats*10 + status (to fit into a uint8_t)
send_sport_frame(SPORT_DATA_FRAME, DATA_ID_TEMP2, (uint16_t)(AP::gps().num_sats() * 10 + AP::gps().status())); // send GPS status and number of satellites as num_sats*10 + status (to fit into a uint8_t)
break;
case 1:
send_uint32(SPORT_DATA_FRAME, DATA_ID_TEMP1, gcs().custom_mode()); // send flight mode
send_sport_frame(SPORT_DATA_FRAME, DATA_ID_TEMP1, gcs().custom_mode()); // send flight mode
break;
}
if (++_SPort.various_call > 1) {
@ -422,34 +422,11 @@ void AP_Frsky_Telem::loop(void)
}
}
/*
* build up the frame's crc
* for FrSky SPort protocol (X-receivers)
*/
void AP_Frsky_Telem::calc_crc(uint8_t byte)
{
_crc += byte; //0-1FF
_crc += _crc >> 8; //0-100
_crc &= 0xFF;
}
/*
* send the frame's crc at the end of the frame
* for FrSky SPort protocol (X-receivers)
*/
void AP_Frsky_Telem::send_crc(void)
{
send_byte(0xFF - _crc);
_crc = 0;
}
/*
send 1 byte and do byte stuffing
*/
void AP_Frsky_Telem::send_byte(uint8_t byte)
{
if (_protocol == AP_SerialManager::SerialProtocol_FrSky_D) { // FrSky D protocol (D-receivers)
if (byte == START_STOP_D) {
_port->write(0x5D);
_port->write(0x3E);
@ -459,42 +436,66 @@ void AP_Frsky_Telem::send_byte(uint8_t byte)
} else {
_port->write(byte);
}
} else { // FrSky SPort protocol (X-receivers)
if (byte == START_STOP_SPORT) {
_port->write(0x7D);
_port->write(0x5E);
} else if (byte == BYTESTUFF_SPORT) {
_port->write(0x7D);
_port->write(0x5D);
} else {
_port->write(byte);
}
calc_crc(byte);
}
}
/*
* send one uint32 frame of FrSky data - for FrSky SPort protocol (X-receivers)
* send an 8 bytes SPort frame of FrSky data - for FrSky SPort protocol (X-receivers)
*/
void AP_Frsky_Telem::send_uint32(uint8_t frame, uint16_t id, uint32_t data)
void AP_Frsky_Telem::send_sport_frame(uint8_t frame, uint16_t appid, uint32_t data)
{
if (use_external_data) {
external_data.frame = frame;
external_data.appid = id;
external_data.appid = appid;
external_data.data = data;
external_data.pending = true;
return;
}
send_byte(frame); // frame type
uint8_t *bytes = (uint8_t*)&id;
send_byte(bytes[0]); // LSB
send_byte(bytes[1]); // MSB
bytes = (uint8_t*)&data;
send_byte(bytes[0]); // LSB
send_byte(bytes[1]);
send_byte(bytes[2]);
send_byte(bytes[3]); // MSB
send_crc();
uint8_t buf[8];
buf[0] = frame;
buf[1] = appid & 0xFF;
buf[2] = appid >> 8;
memcpy(&buf[3], &data, 4);
uint16_t sum = 0;
for (uint8_t i=0; i<sizeof(buf)-1; i++) {
sum += buf[i];
sum += sum >> 8;
sum &= 0xFF;
}
sum = 0xff - ((sum & 0xff) + (sum >> 8));
buf[7] = (uint8_t)sum;
// perform byte stuffing per SPort spec
uint8_t len = 0;
uint8_t buf2[sizeof(buf)*2+1];
for (uint8_t i=0; i<sizeof(buf); i++) {
uint8_t c = buf[i];
if (c == FRAME_DLE || buf[i] == FRAME_HEAD) {
buf2[len++] = FRAME_DLE;
buf2[len++] = c ^ FRAME_XOR;
} else {
buf2[len++] = c;
}
}
/*
check that we haven't been too slow in responding to the new
UART data. If we respond too late then we will overwrite the next
polling frame.
SPort poll-to-pool period is 11.65ms, a frame takes 1.38ms
this leaves us with up to 10ms to respond but to play it safe we
allow no more than 7500us
*/
uint64_t tend = _port->receive_time_constraint_us(1);
uint64_t now = AP_HAL::micros64();
uint64_t tdelay = now - tend;
if (tdelay > 7500) {
// we've been too slow in responding
return;
}
_port->write(buf2, len);
}
/*

12
libraries/AP_Frsky_Telem/AP_Frsky_Telem.h
View File

@ -57,14 +57,16 @@ for FrSky SPort and SPort Passthrough (OpenTX) protocols (X-receivers)
#define SENSOR_ID_FAS 0x22 // Sensor ID 2
#define SENSOR_ID_GPS 0x83 // Sensor ID 3
#define SENSOR_ID_SP2UR 0xC6 // Sensor ID 6
#define SENSOR_ID_28 0x1B // Sensor ID 28
#define SENSOR_ID_27 0x1B // Sensor ID 27
// FrSky data IDs
#define GPS_LONG_LATI_FIRST_ID 0x0800
#define DIY_FIRST_ID 0x5000
#define START_STOP_SPORT 0x7E
#define BYTESTUFF_SPORT 0x7D
#define FRAME_HEAD 0x7E
#define FRAME_DLE 0x7D
#define FRAME_XOR 0x20
#define SPORT_DATA_FRAME 0x10
/*
for FrSky SPort Passthrough
@ -218,11 +220,9 @@ private:
// tick - main call to send updates to transmitter (called by scheduler at 1kHz)
void loop(void);
// methods related to the nuts-and-bolts of sending data
void calc_crc(uint8_t byte);
void send_crc(void);
void send_byte(uint8_t value);
void send_uint16(uint16_t id, uint16_t data);
void send_uint32(uint8_t frame, uint16_t id, uint32_t data);
void send_sport_frame(uint8_t frame, uint16_t appid, uint32_t data);
// methods to convert flight controller data to FrSky SPort Passthrough (OpenTX) format
bool get_next_msg_chunk(void) override;