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ardupilot/libraries/AP_GPS/GPS_Backend.cpp

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/*
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/>.
*/
#include "AP_GPS.h"
#include "GPS_Backend.h"
#include <AP_Logger/AP_Logger.h>
#include <time.h>
#include <AP_RTC/AP_RTC.h>
#include <AP_InternalError/AP_InternalError.h>
#define GPS_BACKEND_DEBUGGING 0
#if GPS_BACKEND_DEBUGGING
# define Debug(fmt, args ...) do {hal.console->printf("%s:%d: " fmt "\n", __FUNCTION__, __LINE__, ## args); hal.scheduler->delay(1); } while(0)
#else
# define Debug(fmt, args ...)
#endif
#include <GCS_MAVLink/GCS.h>
#if AP_GPS_DEBUG_LOGGING_ENABLED
#include <AP_Filesystem/AP_Filesystem.h>
#endif
extern const AP_HAL::HAL& hal;
AP_GPS_Backend::AP_GPS_Backend(AP_GPS &_gps, AP_GPS::GPS_State &_state, AP_HAL::UARTDriver *_port) :
port(_port),
gps(_gps),
state(_state)
{
state.have_speed_accuracy = false;
state.have_horizontal_accuracy = false;
state.have_vertical_accuracy = false;
}
int32_t AP_GPS_Backend::swap_int32(int32_t v) const
{
const uint8_t *b = (const uint8_t *)&v;
union {
int32_t v;
uint8_t b[4];
} u;
u.b[0] = b[3];
u.b[1] = b[2];
u.b[2] = b[1];
u.b[3] = b[0];
return u.v;
}
int16_t AP_GPS_Backend::swap_int16(int16_t v) const
{
const uint8_t *b = (const uint8_t *)&v;
union {
int16_t v;
uint8_t b[2];
} u;
u.b[0] = b[1];
u.b[1] = b[0];
return u.v;
}
/**
fill in time_week_ms and time_week from BCD date and time components
assumes MTK19 millisecond form of bcd_time
*/
void AP_GPS_Backend::make_gps_time(uint32_t bcd_date, uint32_t bcd_milliseconds)
{
struct tm tm {};
tm.tm_year = 100U + bcd_date % 100U;
tm.tm_mon = ((bcd_date / 100U) % 100U)-1;
tm.tm_mday = bcd_date / 10000U;
uint32_t v = bcd_milliseconds;
uint16_t msec = v % 1000U; v /= 1000U;
tm.tm_sec = v % 100U; v /= 100U;
tm.tm_min = v % 100U; v /= 100U;
tm.tm_hour = v % 100U;
// convert from time structure to unix time
time_t unix_time = AP::rtc().mktime(&tm);
// convert to time since GPS epoch
const uint32_t unix_to_GPS_secs = 315964800UL;
const uint16_t leap_seconds_unix = GPS_LEAPSECONDS_MILLIS/1000U;
uint32_t ret = unix_time + leap_seconds_unix - unix_to_GPS_secs;
// get GPS week and time
state.time_week = ret / AP_SEC_PER_WEEK;
state.time_week_ms = (ret % AP_SEC_PER_WEEK) * AP_MSEC_PER_SEC;
state.time_week_ms += msec;
}
/*
get the last time of week in ms
*/
uint32_t AP_GPS_Backend::get_last_itow_ms(void) const
{
if (!_have_itow) {
return state.time_week_ms;
}
return (_pseudo_itow_delta_ms == 0)?(_last_itow_ms):((_pseudo_itow/1000ULL) + _pseudo_itow_delta_ms);
}
/*
fill in 3D velocity for a GPS that doesn't give vertical velocity numbers
*/
void AP_GPS_Backend::fill_3d_velocity(void)
{
float gps_heading = radians(state.ground_course);
state.velocity.x = state.ground_speed * cosf(gps_heading);
state.velocity.y = state.ground_speed * sinf(gps_heading);
state.velocity.z = 0;
state.have_vertical_velocity = false;
}
/*
fill in 3D velocity for a GPS that doesn't give vertical velocity numbers
*/
void AP_GPS_Backend::velocity_to_speed_course(AP_GPS::GPS_State &s)
{
s.ground_course = wrap_360(degrees(atan2f(s.velocity.y, s.velocity.x)));
s.ground_speed = s.velocity.xy().length();
}
void
AP_GPS_Backend::inject_data(const uint8_t *data, uint16_t len)
{
// not all backends have valid ports
if (port != nullptr) {
if (port->txspace() > len) {
port->write(data, len);
} else {
Debug("GPS %d: Not enough TXSPACE", state.instance + 1);
}
}
}
void AP_GPS_Backend::_detection_message(char *buffer, const uint8_t buflen) const
{
const uint8_t instance = state.instance;
const struct AP_GPS::detect_state dstate = gps.detect_state[instance];
if (dstate.auto_detected_baud) {
hal.util->snprintf(buffer, buflen,
"GPS %d: detected as %s at %d baud",
instance + 1,
name(),
int(gps._baudrates[dstate.current_baud]));
} else {
hal.util->snprintf(buffer, buflen,
"GPS %d: specified as %s",
instance + 1,
name());
}
}
void AP_GPS_Backend::broadcast_gps_type() const
{
char buffer[MAVLINK_MSG_STATUSTEXT_FIELD_TEXT_LEN+1];
_detection_message(buffer, sizeof(buffer));
GCS_SEND_TEXT(MAV_SEVERITY_INFO, "%s", buffer);
}
void AP_GPS_Backend::Write_AP_Logger_Log_Startup_messages() const
{
#if HAL_LOGGING_ENABLED
char buffer[MAVLINK_MSG_STATUSTEXT_FIELD_TEXT_LEN+1];
_detection_message(buffer, sizeof(buffer));
AP::logger().Write_Message(buffer);
#endif
}
bool AP_GPS_Backend::should_log() const
{
return gps.should_log();
}
void AP_GPS_Backend::send_mavlink_gps_rtk(mavlink_channel_t chan)
{
#if HAL_GCS_ENABLED
const uint8_t instance = state.instance;
// send status
switch (instance) {
case 0:
mavlink_msg_gps_rtk_send(chan,
0, // Not implemented yet
0, // Not implemented yet
state.rtk_week_number,
state.rtk_time_week_ms,
0, // Not implemented yet
0, // Not implemented yet
state.rtk_num_sats,
state.rtk_baseline_coords_type,
state.rtk_baseline_x_mm,
state.rtk_baseline_y_mm,
state.rtk_baseline_z_mm,
state.rtk_accuracy,
state.rtk_iar_num_hypotheses);
break;
case 1:
mavlink_msg_gps2_rtk_send(chan,
0, // Not implemented yet
0, // Not implemented yet
state.rtk_week_number,
state.rtk_time_week_ms,
0, // Not implemented yet
0, // Not implemented yet
state.rtk_num_sats,
state.rtk_baseline_coords_type,
state.rtk_baseline_x_mm,
state.rtk_baseline_y_mm,
state.rtk_baseline_z_mm,
state.rtk_accuracy,
state.rtk_iar_num_hypotheses);
break;
}
#endif
}
/*
set a timestamp based on arrival time on uart at current byte,
assuming the message started nbytes ago
*/
void AP_GPS_Backend::set_uart_timestamp(uint16_t nbytes)
{
if (port) {
state.last_corrected_gps_time_us = port->receive_time_constraint_us(nbytes);
state.corrected_timestamp_updated = true;
}
}
void AP_GPS_Backend::check_new_itow(uint32_t itow, uint32_t msg_length)
{
if (itow != _last_itow_ms) {
_last_itow_ms = itow;
_have_itow = true;
/*
we need to calculate a pseudo-itow, which copes with the
iTow from the GPS changing in unexpected ways. We assume
that timestamps from the GPS are always in multiples of
50ms. That means we can't handle a GPS with an update rate
of more than 20Hz. We could do more, but we'd need the GPS
poll time to be higher
*/
const uint32_t gps_min_period_ms = 50;
// get the time the packet arrived on the UART
uint64_t uart_us;
if (_last_pps_time_us != 0 && (state.status >= AP_GPS::GPS_OK_FIX_2D)) {
// pps is only reliable when we have some sort of GPS fix
uart_us = _last_pps_time_us;
_last_pps_time_us = 0;
} else if (port) {
uart_us = port->receive_time_constraint_us(msg_length);
} else {
uart_us = AP_HAL::micros64();
}
uint32_t now = AP_HAL::millis();
uint32_t dt_ms = now - _last_ms;
_last_ms = now;
// round to nearest 50ms period
dt_ms = ((dt_ms + (gps_min_period_ms/2)) / gps_min_period_ms) * gps_min_period_ms;
// work out an actual message rate. If we get 5 messages in a
// row with a new rate we switch rate
if (_last_rate_ms == dt_ms) {
if (_rate_counter < 5) {
_rate_counter++;
} else if (_rate_ms != dt_ms) {
_rate_ms = dt_ms;
}
} else {
_rate_counter = 0;
_last_rate_ms = dt_ms;
if (_rate_ms != 0) {
set_pps_desired_freq(1000/_rate_ms);
}
}
if (_rate_ms == 0) {
// only allow 5Hz to 20Hz in user config
_rate_ms = constrain_int16(gps.get_rate_ms(state.instance), 50, 200);
}
// round to calculated message rate
dt_ms = ((dt_ms + (_rate_ms/2)) / _rate_ms) * _rate_ms;
// calculate pseudo-itow
_pseudo_itow += dt_ms * 1000U;
// use msg arrival time, and correct for jitter
uint64_t local_us = jitter_correction.correct_offboard_timestamp_usec(_pseudo_itow, uart_us);
state.last_corrected_gps_time_us = local_us;
state.corrected_timestamp_updated = true;
#ifndef HAL_BUILD_AP_PERIPH
// look for lagged data from the GPS. This is meant to detect
// the case that the GPS is trying to push more data into the
// UART than can fit (eg. with GPS_RAW_DATA at 115200).
// This is disabled on AP_Periph as it is better to catch missed packet rate at the flight
// controller level
float expected_lag;
if (gps.get_lag(state.instance, expected_lag)) {
float lag_s = (now - (state.last_corrected_gps_time_us/1000U)) * 0.001;
if (lag_s > expected_lag+0.05) {
// more than 50ms over expected lag, increment lag counter
state.lagged_sample_count++;
} else {
state.lagged_sample_count = 0;
}
}
#endif // HAL_BUILD_AP_PERIPH
if (state.status >= AP_GPS::GPS_OK_FIX_2D) {
// we must have a decent fix to calculate difference between itow and pseudo-itow
_pseudo_itow_delta_ms = itow - (_pseudo_itow/1000ULL);
}
}
}
#if GPS_MOVING_BASELINE
bool AP_GPS_Backend::calculate_moving_base_yaw(float reported_heading_deg, const float reported_distance, const float reported_D) {
return calculate_moving_base_yaw(state, reported_heading_deg, reported_distance, reported_D);
}
bool AP_GPS_Backend::calculate_moving_base_yaw(AP_GPS::GPS_State &interim_state, const float reported_heading_deg, const float reported_distance, const float reported_D) {
constexpr float minimum_antenna_seperation = 0.05; // meters
constexpr float permitted_error_length_pct = 0.2; // percentage
bool selectedOffset = false;
Vector3f offset;
switch (MovingBase::Type(gps.mb_params[interim_state.instance].type.get())) {
case MovingBase::Type::RelativeToAlternateInstance:
offset = gps._antenna_offset[interim_state.instance^1].get() - gps._antenna_offset[interim_state.instance].get();
selectedOffset = true;
break;
case MovingBase::Type::RelativeToCustomBase:
offset = gps.mb_params[interim_state.instance].base_offset.get();
selectedOffset = true;
break;
}
if (!selectedOffset) {
// invalid type, let's throw up a flag
INTERNAL_ERROR(AP_InternalError::error_t::flow_of_control);
goto bad_yaw;
}
{
const float offset_dist = offset.length();
const float min_dist = MIN(offset_dist, reported_distance);
if (offset_dist < minimum_antenna_seperation) {
// offsets have to be sufficently large to get a meaningful angle off of them
Debug("Insufficent antenna offset (%f, %f, %f)", (double)offset.x, (double)offset.y, (double)offset.z);
goto bad_yaw;
}
if (reported_distance < minimum_antenna_seperation) {
// if the reported distance is less then the minimum seperation it's not sufficently robust
Debug("Reported baseline distance (%f) was less then the minimum antenna seperation (%f)",
(double)reported_distance, (double)minimum_antenna_seperation);
goto bad_yaw;
}
if ((offset_dist - reported_distance) > (min_dist * permitted_error_length_pct)) {
// the magnitude of the vector is much further then we were expecting
Debug("Exceeded the permitted error margin %f > %f",
(double)(offset_dist - reported_distance), (double)(min_dist * permitted_error_length_pct));
goto bad_yaw;
}
#ifndef HAL_BUILD_AP_PERIPH
{
// get lag
float lag = 0.1;
get_lag(lag);
// get vehicle rotation, projected back in time using the gyro
// this is not 100% accurate, but it is good enough for
// this test. To do it completely accurately we'd need an
// interface into DCM, EKF2 and EKF3 to ask for a
// historical attitude. That is far too complex to justify
// for this use case
const auto &ahrs = AP::ahrs();
const Vector3f &gyro = ahrs.get_gyro();
Matrix3f rot_body_to_ned = ahrs.get_rotation_body_to_ned();
rot_body_to_ned.rotate(gyro * (-lag));
// apply rotation to the offset to get the Z offset in NED
const Vector3f antenna_tilt = rot_body_to_ned * offset;
const float alt_error = reported_D + antenna_tilt.z;
if (fabsf(alt_error) > permitted_error_length_pct * min_dist) {
// the vertical component is out of range, reject it
Debug("bad alt_err %.1f > %.1f\n",
alt_error, permitted_error_length_pct * min_dist);
goto bad_yaw;
}
}
#endif // HAL_BUILD_AP_PERIPH
{
// at this point the offsets are looking okay, go ahead and actually calculate a useful heading
const float rotation_offset_rad = Vector2f(-offset.x, -offset.y).angle();
interim_state.gps_yaw = wrap_360(reported_heading_deg - degrees(rotation_offset_rad));
interim_state.have_gps_yaw = true;
interim_state.gps_yaw_time_ms = AP_HAL::millis();
}
goto good_yaw;
}
bad_yaw:
interim_state.have_gps_yaw = false;
good_yaw:
#if HAL_LOGGING_ENABLED
// this log message helps diagnose GPS yaw issues
// @LoggerMessage: GPYW
// @Description: GPS Yaw
// @Field: TimeUS: Time since system startup
// @Field: Id: instance
// @Field: RHD: reported heading,deg
// @Field: RDist: antenna separation,m
// @Field: RDown: vertical antenna separation,m
// @Field: OK: 1 if have yaw
AP::logger().WriteStreaming("GPYW", "TimeUS,Id,RHD,RDist,RDown,OK",
"s#dmm-",
"F-----",
"QBfffB",
AP_HAL::micros64(),
state.instance,
reported_heading_deg,
reported_distance,
reported_D,
interim_state.have_gps_yaw);
#endif
return interim_state.have_gps_yaw;
}
#endif // GPS_MOVING_BASELINE
#if AP_GPS_DEBUG_LOGGING_ENABLED
/*
log some data for debugging
the logging format matches that used by SITL with SIM_GPS_TYPE=7,
allowing for development of GPS drivers based on logged data
*/
void AP_GPS_Backend::log_data(const uint8_t *data, uint16_t length)
{
if (state.instance < 2) {
logging[state.instance].buf.write(data, length);
}
if (!log_thread_created) {
log_thread_created = true;
hal.scheduler->thread_create(FUNCTOR_BIND_MEMBER(&AP_GPS_Backend::logging_start, void), "gps_log", 4096, AP_HAL::Scheduler::PRIORITY_IO, 0);
}
}
AP_GPS_Backend::loginfo AP_GPS_Backend::logging[2];
bool AP_GPS_Backend::log_thread_created;
// logging loop, needs to be static to allow for re-alloc of GPS backends
void AP_GPS_Backend::logging_loop(void)
{
while (true) {
hal.scheduler->delay(10);
static uint16_t lognum;
for (uint8_t instance=0; instance<2; instance++) {
if (logging[instance].fd == -1 && logging[instance].buf.available()) {
char fname[] = "gpsN_XXX.log";
fname[3] = '1' + instance;
if (lognum == 0) {
for (lognum=1; lognum<1000; lognum++) {
struct stat st;
hal.util->snprintf(&fname[5], 8, "%03u.log", lognum);
if (AP::FS().stat(fname, &st) != 0) {
break;
}
}
}
hal.util->snprintf(&fname[5], 8, "%03u.log", lognum);
logging[instance].fd = AP::FS().open(fname, O_WRONLY|O_CREAT|O_APPEND);
}
if (logging[instance].fd != -1) {
uint32_t n = 0;
const uint8_t *p;
while ((p = logging[instance].buf.readptr(n)) != nullptr && n != 0) {
struct {
uint32_t magic = 0x7fe53b04U;
uint32_t time_ms;
uint32_t n;
} header;
header.n = n;
header.time_ms = AP_HAL::millis();
// short writes are unlikely and are ignored (only FS full errors)
AP::FS().write(logging[instance].fd, (const uint8_t *)&header, sizeof(header));
AP::FS().write(logging[instance].fd, p, n);
logging[instance].buf.advance(n);
AP::FS().fsync(logging[instance].fd);
}
}
}
}
}
// logging thread start, needs to be non-static for thread_create
void AP_GPS_Backend::logging_start(void)
{
logging_loop();
}
#endif // AP_GPS_DEBUG_LOGGING_ENABLED
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