ardupilot/libraries/AP_NMEA_Output/AP_NMEA_Output.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/>.
Author: Francisco Ferreira (some code is copied from sitl_gps.cpp)
*/
#define ALLOW_DOUBLE_MATH_FUNCTIONS
#include "AP_NMEA_Output.h"
#if HAL_NMEA_OUTPUT_ENABLED
#include <AP_Math/definitions.h>
#include <AP_RTC/AP_RTC.h>
#include <AP_GPS/AP_GPS.h>
#include <AP_SerialManager/AP_SerialManager.h>
#include <AP_Common/NMEA.h>
#include <stdio.h>
#include <time.h>
#include <AP_AHRS/AP_AHRS_config.h>
#if AP_AHRS_ENABLED
#include <AP_AHRS/AP_AHRS.h>
#endif
#ifndef AP_NMEA_OUTPUT_MESSAGE_ENABLED_DEFAULT
#define AP_NMEA_OUTPUT_MESSAGE_ENABLED_DEFAULT 3 // GPGGA and GPRMC
#endif
#define AP_NMEA_OUTPUT_INTERVAL_MS_MIN 10
#define AP_NMEA_OUTPUT_INTERVAL_MS_MAX 5000
extern const AP_HAL::HAL& hal;
const AP_Param::GroupInfo AP_NMEA_Output::var_info[] = {
// @Param: RATE_MS
// @DisplayName: NMEA Output rate
// @Description: NMEA Output rate. This controls the interval at which all the enabled NMEA messages are sent. Most NMEA systems expect 100ms (10Hz) or slower.
// @Range: 20 2000
// @Increment: 1
// @Units: ms
// @User: Standard
AP_GROUPINFO("RATE_MS", 1, AP_NMEA_Output, _interval_ms, 100),
// @Param: MSG_EN
// @DisplayName: Messages Enable bitmask
// @Description: This is a bitmask of enabled NMEA messages. All messages will be sent consecutively at the same rate interval
// @Bitmask: 0:GPGGA,1:GPRMC,2:PASHR
// @User: Standard
AP_GROUPINFO("MSG_EN", 2, AP_NMEA_Output, _message_enable_bitmask, AP_NMEA_OUTPUT_MESSAGE_ENABLED_DEFAULT),
AP_GROUPEND
};
void AP_NMEA_Output::init()
{
const AP_SerialManager& sm = AP::serialmanager();
_num_outputs = 0;
for (uint8_t i = 0; i < ARRAY_SIZE(_uart); i++) {
_uart[i] = sm.find_serial(AP_SerialManager::SerialProtocol_NMEAOutput, i);
if (_uart[i] == nullptr) {
break;
}
_num_outputs++;
}
}
void AP_NMEA_Output::update()
{
if (_num_outputs == 0 || _message_enable_bitmask == 0) {
return;
}
const uint32_t now_ms = AP_HAL::millis();
if ((now_ms - _last_run_ms) < static_cast<uint32_t>(MAX(_interval_ms.get(), 20))) {
return;
}
_last_run_ms = now_ms;
// get time and date
uint64_t time_usec;
#if AP_RTC_ENABLED
if (!AP::rtc().get_utc_usec(time_usec)) {
return;
}
#else
time_usec = 0;
#endif
uint32_t space_required = 0;
// not completely accurate, our time includes leap seconds and time_t should be without
const time_t time_sec = time_usec / 1000000;
struct tm* tm = gmtime(&time_sec);
// format time string
char tstring[11];
snprintf(tstring, sizeof(tstring), "%02u%02u%06.2f", tm->tm_hour, tm->tm_min, tm->tm_sec + (time_usec % 1000000) * 1.0e-6);
Location loc;
const auto &gps = AP::gps();
const AP_GPS::GPS_Status gps_status = gps.status();
#if AP_AHRS_ENABLED
auto &ahrs = AP::ahrs();
// NOTE: ahrs.get_location() always returns true after having GPS position once because it will be dead-reckoning
const bool pos_valid = ahrs.get_location(loc);
#else
const bool pos_valid = (gps_status >= AP_GPS::GPS_OK_FIX_3D);
loc = gps.location();
#endif
// format latitude
char lat_string[13];
double deg = fabs(loc.lat * 1.0e-7f);
double min_dec = ((fabs(loc.lat) - (unsigned)deg * 1.0e7)) * 60 * 1.e-7f;
snprintf(lat_string,
sizeof(lat_string),
"%02u%08.5f,%c",
(unsigned) deg,
min_dec,
loc.lat < 0 ? 'S' : 'N');
// format longitude
char lng_string[14];
deg = fabs(loc.lng * 1.0e-7f);
min_dec = ((fabs(loc.lng) - (unsigned)deg * 1.0e7)) * 60 * 1.e-7f;
snprintf(lng_string,
sizeof(lng_string),
"%03u%08.5f,%c",
(unsigned) deg,
min_dec,
loc.lng < 0 ? 'W' : 'E');
char gga[100];
uint16_t gga_length = 0;
if ((_message_enable_bitmask.get() & static_cast<int16_t>(Enabled_Messages::GPGGA)) != 0) {
// format GGA message
// Convert AP_GPS::GPS_Status:
// 0 = NO_GPS
// 1 = NO_FIX
// 2 = GPS_OK_FIX_2D
// 3 = GPS_OK_FIX_3D
// 4 = GPS_OK_FIX_3D_DGPS
// 5 = GPS_OK_FIX_3D_RTK_FLOAT
// 6 = GPS_OK_FIX_3D_RTK_FIXED
// To NMEA "Fix Quality" per Trimble definition:
// 0: Fix not valid
// 1: GPS fix
// 2: Differential GPS fix (DGNSS), SBAS, OmniSTAR VBS, Beacon, RTX in GVBS mode
// 3: Not applicable
// 4: RTK Fixed, xFill
// 5: RTK Float, OmniSTAR XP/HP, Location RTK, RTX
// 6: INS Dead reckoning
// sources:
// https://orolia.com/manuals/VSP/Content/NC_and_SS/Com/Topics/APPENDIX/NMEA_GGAmess.htm
// http://aprs.gids.nl/nmea/#gga
// https://docs.novatel.com/OEM7/Content/Logs/GPGGA.htm
// https://receiverhelp.trimble.com/alloy-gnss/en-us/NMEA-0183messages_GGA.html <-using this one
uint8_t fix_quality;
switch (gps_status) {
default:
case AP_GPS::NO_GPS:
case AP_GPS::NO_FIX:
case AP_GPS::GPS_OK_FIX_2D:
// NOTE: ahrs.get_location() always returns pos_valid=true after having GPS position once because it will be dead-reckoning
fix_quality = pos_valid ? 6 : 0;
break;
case AP_GPS::GPS_OK_FIX_3D:
fix_quality = 1;
break;
case AP_GPS::GPS_OK_FIX_3D_DGPS:
fix_quality = 2;
break;
case AP_GPS::GPS_OK_FIX_3D_RTK_FLOAT:
fix_quality = 5;
break;
case AP_GPS::GPS_OK_FIX_3D_RTK_FIXED:
fix_quality = 4;
break;
}
gga_length = nmea_printf_buffer(gga, sizeof(gga),
"$GPGGA,%s,%s,%s,%01d,%02d,%04.1f,%07.2f,M,0.0,M,,",
tstring,
lat_string,
lng_string,
fix_quality,
gps.num_sats(),
gps.get_hdop(),
loc.alt * 0.01f);
space_required += gga_length;
}
char rmc[100];
uint16_t rmc_length = 0;
if ((_message_enable_bitmask.get() & static_cast<int16_t>(Enabled_Messages::GPRMC)) != 0) {
// format date string
char dstring[7];
snprintf(dstring, sizeof(dstring), "%02u%02u%02u", tm->tm_mday, tm->tm_mon+1, tm->tm_year % 100);
// get speed
#if AP_AHRS_ENABLED
const Vector2f speed = ahrs.groundspeed_vector();
const float speed_knots = speed.length() * M_PER_SEC_TO_KNOTS;
const float heading = wrap_360(degrees(atan2f(speed.x, speed.y)));
#else
const float speed_knots = gps.ground_speed() * M_PER_SEC_TO_KNOTS;
const float heading = gps.ground_course();
#endif
// format RMC message
rmc_length = nmea_printf_buffer(rmc, sizeof(rmc),
"$GPRMC,%s,%c,%s,%s,%.2f,%.2f,%s,,",
tstring,
pos_valid ? 'A' : 'V',
lat_string,
lng_string,
speed_knots,
heading,
dstring);
space_required += rmc_length;
}
uint16_t pashr_length = 0;
char pashr[100];
#if AP_AHRS_ENABLED
if ((_message_enable_bitmask.get() & static_cast<int16_t>(Enabled_Messages::PASHR)) != 0) {
// get roll, pitch, yaw
const float roll_deg = wrap_180(degrees(ahrs.get_roll()));
const float pitch_deg = wrap_180(degrees(ahrs.get_pitch()));
const float yaw_deg = wrap_360(degrees(ahrs.get_yaw()));
const float heave_m = 0; // instantaneous heave in meters
const float roll_deg_accuracy = 0; // stddev of roll_deg;
const float pitch_deg_accuracy = 0; // stddev of pitch_deg;
const float heading_deg_accuracy = 0; // stddev of yaw_deg;
// GPS Update Quality Flag:
// 0 = no position
// 1 = All non-RTK fixed integer positions
// 2 = RTK fixed integer positions
const uint8_t gps_status_flag = (gps_status >= AP_GPS::GPS_OK_FIX_3D_RTK_FIXED) ? 2 :
(gps_status >= AP_GPS::GPS_OK_FIX_2D ? 1 : 0);
// INS Status Flag:
// 0 = All SPAN Pre-Alignment INS Status
// 1 = All SPAN Post-Alignment INS Status
const bool ins_status_flag = ahrs.initialised() &&
ahrs.healthy() &&
(!ahrs.have_inertial_nav() || AP::ins().accel_calibrated_ok_all());
// format PASHR message
pashr_length = nmea_printf_buffer(pashr, sizeof(pashr),
"$PASHR,%s,%.2f,T,%c%.2f,%c%.2f,%c%.2f,%.3f,%.3f,%.3f,%u,%u",
tstring,
yaw_deg, // This is a TRUE NORTH value
roll_deg<0? '-':'+', fabs(roll_deg), // always show + or - symbol
pitch_deg<0?'-':'+', fabs(pitch_deg), // always show + or - symbol
heave_m<0? '-':'+', fabs(heave_m), // always show + or - symbol
roll_deg_accuracy,
pitch_deg_accuracy,
heading_deg_accuracy,
(unsigned)gps_status_flag,
(unsigned)ins_status_flag);
space_required += pashr_length;
}
#endif
// send to all NMEA output ports
for (uint8_t i = 0; i < _num_outputs; i++) {
if (_uart[i]->txspace() < space_required) {
continue;
}
if (gga_length > 0) {
_uart[i]->write(gga);
}
if (rmc_length > 0) {
_uart[i]->write(rmc);
}
if (pashr_length > 0) {
_uart[i]->write(pashr);
}
}
}
#endif // HAL_NMEA_OUTPUT_ENABLED