ardupilot/libraries/AP_RCProtocol/AP_RCProtocol_CRSF.cpp

401 lines
12 KiB
C++

/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
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.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
CRSF protocol decoder based on betaflight implementation
Code by Andy Piper
*/
#include "AP_RCProtocol.h"
#include "AP_RCProtocol_SRXL.h"
#include "AP_RCProtocol_CRSF.h"
#include <AP_HAL/AP_HAL.h>
#include <AP_Math/AP_Math.h>
#include <AP_Math/crc.h>
#include <AP_Vehicle/AP_Vehicle_Type.h>
#include <AP_RCTelemetry/AP_CRSF_Telem.h>
#include <AP_SerialManager/AP_SerialManager.h>
/*
* CRSF protocol
*
* CRSF protocol uses a single wire half duplex uart connection.
* The master sends one frame every 4ms and the slave replies between two frames from the master.
*
* 420000 baud
* not inverted
* 8 Bit
* 1 Stop bit
* Big endian
* 416666 bit/s = 46667 byte/s (including stop bit) = 21.43us per byte
* Max frame size is 64 bytes
* A 64 byte frame plus 1 sync byte can be transmitted in 1393 microseconds.
*
* CRSF_TIME_NEEDED_PER_FRAME_US is set conservatively at 1500 microseconds
*
* Every frame has the structure:
* <Device address><Frame length><Type><Payload><CRC>
*
* Device address: (uint8_t)
* Frame length: length in bytes including Type (uint8_t)
* Type: (uint8_t)
* CRC: (uint8_t)
*
*/
extern const AP_HAL::HAL& hal;
// #define CRSF_DEBUG
#ifdef CRSF_DEBUG
# define debug(fmt, args...) hal.console->printf("CRSF: " fmt "\n", ##args)
static const char* get_frame_type(uint8_t byte)
{
switch(byte) {
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_GPS:
return "GPS";
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_BATTERY_SENSOR:
return "BATTERY";
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_HEARTBEAT:
return "HEARTBEAT";
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_VTX:
return "VTX";
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_VTX_TELEM:
return "VTX_TELEM";
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_PARAM_DEVICE_PING:
return "PING";
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_COMMAND:
return "COMMAND";
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_ATTITUDE:
return "ATTITUDE";
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_FLIGHT_MODE:
return "FLIGHT_MODE";
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_PARAM_DEVICE_INFO:
return "DEVICE_INFO";
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_PARAMETER_READ:
return "PARAM_READ";
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_PARAMETER_SETTINGS_ENTRY:
return "SETTINGS_ENTRY";
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_LINK_STATISTICS:
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_RC_CHANNELS_PACKED:
case AP_RCProtocol_CRSF::CRSF_FRAMETYPE_PARAMETER_WRITE:
return "UNKNOWN";
}
return "UNKNOWN";
}
#else
# define debug(fmt, args...) do {} while(0)
#endif
#define CRSF_MAX_FRAME_TIME_US 1100U // 700us + 400us for potential ad-hoc request
#define CRSF_INTER_FRAME_TIME_US_150HZ 6667U // At fastest, frames are sent by the transmitter every 6.667 ms, 150 Hz
#define CRSF_INTER_FRAME_TIME_US_50HZ 20000U // At slowest, frames are sent by the transmitter every 20ms, 50 Hz
#define CSRF_HEADER_LEN 2
#define CRSF_DIGITAL_CHANNEL_MIN 172
#define CRSF_DIGITAL_CHANNEL_MAX 1811
AP_RCProtocol_CRSF* AP_RCProtocol_CRSF::_singleton;
AP_RCProtocol_CRSF::AP_RCProtocol_CRSF(AP_RCProtocol &_frontend) : AP_RCProtocol_Backend(_frontend)
{
#if !APM_BUILD_TYPE(APM_BUILD_UNKNOWN)
if (_singleton != nullptr) {
AP_HAL::panic("Duplicate CRSF handler");
}
_singleton = this;
#else
if (_singleton == nullptr) {
_singleton = this;
}
#endif
#if HAL_CRSF_TELEM_ENABLED && !APM_BUILD_TYPE(APM_BUILD_iofirmware) && !APM_BUILD_TYPE(APM_BUILD_UNKNOWN)
_uart = AP::serialmanager().find_serial(AP_SerialManager::SerialProtocol_CRSF, 0);
if (_uart) {
start_uart();
}
#endif
}
AP_RCProtocol_CRSF::~AP_RCProtocol_CRSF() {
_singleton = nullptr;
}
void AP_RCProtocol_CRSF::process_pulse(uint32_t width_s0, uint32_t width_s1)
{
uint8_t b;
if (ss.process_pulse(width_s0, width_s1, b)) {
_process_byte(ss.get_byte_timestamp_us(), b);
}
}
void AP_RCProtocol_CRSF::_process_byte(uint32_t timestamp_us, uint8_t byte)
{
//debug("process_byte(0x%x)", byte);
// we took too long decoding, start again - the RX will only send complete frames so this is unlikely to fail
if (_frame_ofs > 0 && (timestamp_us - _start_frame_time_us) > CRSF_MAX_FRAME_TIME_US) {
_frame_ofs = 0;
}
_last_rx_time_us = timestamp_us;
// overflow check
if (_frame_ofs >= CRSF_FRAMELEN_MAX) {
_frame_ofs = 0;
}
// start of a new frame
if (_frame_ofs == 0) {
_start_frame_time_us = timestamp_us;
}
add_to_buffer(_frame_ofs++, byte);
// need a header to get the length
if (_frame_ofs < CSRF_HEADER_LEN) {
return;
}
// parse the length
if (_frame_ofs == CSRF_HEADER_LEN) {
// check for garbage frame
if (_frame.length > CRSF_FRAMELEN_MAX) {
_frame_ofs = 0;
}
return;
}
// overflow check
if (_frame_ofs > _frame.length + CSRF_HEADER_LEN) {
_frame_ofs = 0;
return;
}
// decode whatever we got and expect
if (_frame_ofs == _frame.length + CSRF_HEADER_LEN) {
log_data(AP_RCProtocol::CRSF, timestamp_us, (const uint8_t*)&_frame, _frame_ofs - CSRF_HEADER_LEN);
if ((timestamp_us - _last_frame_time_us) <= CRSF_INTER_FRAME_TIME_US_150HZ + CRSF_MAX_FRAME_TIME_US) {
_fast_telem = true;
} else {
_fast_telem = false;
}
// we consumed the partial frame, reset
_frame_ofs = 0;
uint8_t crc = crc8_dvb_s2(0, _frame.type);
for (uint8_t i = 0; i < _frame.length - 2; i++) {
crc = crc8_dvb_s2(crc, _frame.payload[i]);
}
// bad CRC
if (crc != _frame.payload[_frame.length - CSRF_HEADER_LEN]) {
return;
}
_last_frame_time_us = timestamp_us;
// decode here
if (decode_csrf_packet()) {
add_input(MAX_CHANNELS, _channels, false, _current_rssi);
}
}
}
void AP_RCProtocol_CRSF::update(void)
{
// if we are in standalone mode, process data from the uart
if (_uart) {
uint32_t now = AP_HAL::millis();
// for some reason it's necessary to keep trying to start the uart until we get data
if (now - _last_uart_start_time_ms > 1000U && _last_frame_time_us == 0) {
start_uart();
_last_uart_start_time_ms = now;
}
uint32_t n = _uart->available();
n = MIN(n, 255U);
for (uint8_t i = 0; i < n; i++) {
int16_t b = _uart->read();
if (b >= 0) {
_process_byte(now, uint8_t(b));
}
}
}
// never received RC frames, but have received CRSF frames so make sure we give the telemetry opportunity to run
uint32_t now = AP_HAL::micros();
if (_last_frame_time_us > 0 && !get_rc_frame_count() && now - _last_frame_time_us > CRSF_INTER_FRAME_TIME_US_150HZ) {
process_telemetry(false);
_last_frame_time_us = now;
}
}
// write out a frame of any type
void AP_RCProtocol_CRSF::write_frame(Frame* frame)
{
AP_HAL::UARTDriver *uart = get_current_UART();
if (!uart) {
return;
}
// calculate crc
uint8_t crc = crc8_dvb_s2(0, frame->type);
for (uint8_t i = 0; i < frame->length - 2; i++) {
crc = crc8_dvb_s2(crc, frame->payload[i]);
}
frame->payload[frame->length - 2] = crc;
uart->write((uint8_t*)frame, frame->length + 2);
#ifdef CRSF_DEBUG
hal.console->printf("CRSF: writing %s:", get_frame_type(frame->type));
for (uint8_t i = 0; i < frame->length + 2; i++) {
uint8_t val = ((uint8_t*)frame)[i];
if (val >= 32 && val <= 126) {
hal.console->printf(" 0x%x '%c'", val, (char)val);
} else {
hal.console->printf(" 0x%x", val);
}
}
hal.console->printf("\n");
#endif
}
bool AP_RCProtocol_CRSF::decode_csrf_packet()
{
#ifdef CRSF_DEBUG
hal.console->printf("CRSF: received %s:", get_frame_type(_frame.type));
uint8_t* fptr = (uint8_t*)&_frame;
for (uint8_t i = 0; i < _frame.length + 2; i++) {
hal.console->printf(" 0x%x", fptr[i]);
}
hal.console->printf("\n");
#endif
bool rc_active = false;
switch (_frame.type) {
case CRSF_FRAMETYPE_RC_CHANNELS_PACKED:
// scale factors defined by TBS - TICKS_TO_US(x) ((x - 992) * 5 / 8 + 1500)
decode_11bit_channels((const uint8_t*)(&_frame.payload), CRSF_MAX_CHANNELS, _channels, 5U, 8U, 880U);
rc_active = !_uart; // only accept RC data if we are not in standalone mode
break;
case CRSF_FRAMETYPE_LINK_STATISTICS:
process_link_stats_frame((uint8_t*)&_frame.payload);
break;
default:
break;
}
#if HAL_CRSF_TELEM_ENABLED && !APM_BUILD_TYPE(APM_BUILD_iofirmware)
if (AP_CRSF_Telem::process_frame(FrameType(_frame.type), (uint8_t*)&_frame.payload)) {
process_telemetry();
}
#endif
return rc_active;
}
// send out telemetry
bool AP_RCProtocol_CRSF::process_telemetry(bool check_constraint)
{
AP_HAL::UARTDriver *uart = get_current_UART();
if (!uart) {
return false;
}
if (!telem_available) {
#if HAL_CRSF_TELEM_ENABLED && !APM_BUILD_TYPE(APM_BUILD_iofirmware)
if (AP_CRSF_Telem::get_telem_data(&_telemetry_frame)) {
telem_available = true;
} else {
return false;
}
#else
return false;
#endif
}
/*
check that we haven't been too slow in responding to the new
UART data. If we respond too late then we will corrupt the next
incoming control frame
*/
uint64_t tend = uart->receive_time_constraint_us(1);
uint64_t now = AP_HAL::micros64();
uint64_t tdelay = now - tend;
if (tdelay > CRSF_MAX_FRAME_TIME_US && check_constraint) {
// we've been too slow in responding
return false;
}
write_frame(&_telemetry_frame);
// get fresh telem_data in the next call
telem_available = false;
return true;
}
// process link statistics to get RSSI
void AP_RCProtocol_CRSF::process_link_stats_frame(const void* data)
{
const LinkStatisticsFrame* link = (const LinkStatisticsFrame*)data;
uint8_t rssi_dbm;
if (link->active_antenna == 0) {
rssi_dbm = link->uplink_rssi_ant1;
} else {
rssi_dbm = link->uplink_rssi_ant2;
}
// AP rssi: -1 for unknown, 0 for no link, 255 for maximum link
if (rssi_dbm < 50) {
_current_rssi = 255;
} else if (rssi_dbm > 120) {
_current_rssi = 0;
} else {
// this is an approximation recommended by Remo from TBS
_current_rssi = int16_t(roundf((1.0f - (rssi_dbm - 50.0f) / 70.0f) * 255.0f));
}
}
// process a byte provided by a uart
void AP_RCProtocol_CRSF::process_byte(uint8_t byte, uint32_t baudrate)
{
// reject RC data if we have been configured for standalone mode
if (baudrate != CRSF_BAUDRATE || _uart) {
return;
}
_process_byte(AP_HAL::micros(), byte);
}
// start the uart if we have one
void AP_RCProtocol_CRSF::start_uart()
{
_uart->configure_parity(0);
_uart->set_stop_bits(1);
_uart->set_flow_control(AP_HAL::UARTDriver::FLOW_CONTROL_DISABLE);
_uart->set_unbuffered_writes(true);
_uart->set_blocking_writes(false);
_uart->set_options(_uart->get_options() & ~AP_HAL::UARTDriver::OPTION_RXINV);
_uart->begin(CRSF_BAUDRATE, 128, 128);
}
namespace AP {
AP_RCProtocol_CRSF* crsf() {
return AP_RCProtocol_CRSF::get_singleton();
}
};