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AP_NMEA_Output: new library for writing NMEA to serial ports

This commit is contained in:
Francisco Ferreira 2019-03-04 18:13:01 +00:00 committed by Andrew Tridgell
parent 0e33907cf7
commit 80093f41b0
2 changed files with 234 additions and 0 deletions
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181
libraries/AP_NMEA_Output/AP_NMEA_Output.cpp Normal file
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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)
*/
#include "AP_NMEA_Output.h"
#if !HAL_MINIMIZE_FEATURES && AP_AHRS_NAVEKF_AVAILABLE
#include <AP_Math/definitions.h>
#include <AP_RTC/AP_RTC.h>
#include <AP_SerialManager/AP_SerialManager.h>
#include <stdio.h>
#include <time.h>
AP_NMEA_Output* AP_NMEA_Output::_singleton;
AP_NMEA_Output::AP_NMEA_Output()
{
AP_SerialManager& sm = AP::serialmanager();
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++;
}
}
AP_NMEA_Output* AP_NMEA_Output::probe()
{
if (!_singleton && AP::serialmanager().find_serial(AP_SerialManager::SerialProtocol_NMEAOutput, 0) != nullptr) {
_singleton = new AP_NMEA_Output();
}
return _singleton;
}
uint8_t AP_NMEA_Output::_nmea_checksum(const char *str)
{
uint8_t checksum = 0;
const uint8_t* bytes = (const uint8_t*) str;
for (uint16_t i = 1; str[i]; i++) {
checksum ^= bytes[i];
}
return checksum;
}
void AP_NMEA_Output::update()
{
uint16_t now = AP_HAL::millis16();
uint16_t time_diff = now - _last_sent;
// only send at 10Hz
if (time_diff < 100) {
return;
}
// get time and date
uint64_t time_usec;
bool time_valid = AP::rtc().get_utc_usec(time_usec);
if (!time_valid) {
return;
}
// not completely accurate, our time includes leap seconds and time_t should be without
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%06.3f", tm->tm_hour, tm->tm_min, tm->tm_sec + (time_usec % 1000000) * 1.0e-6);
// format date string
char dstring[7];
snprintf(dstring, sizeof(dstring), "%02u%02u%02u", tm->tm_mday, tm->tm_mon+1, tm->tm_year % 100);
AP_AHRS_NavEKF& ahrs = AP::ahrs_navekf();
// get location (note: get_position from AHRS always returns true after having GPS position once)
Location loc;
bool pos_valid = ahrs.get_location(loc);
// format latitude
char lat_string[13];
float deg = fabsf(loc.lat * 1.0e-7f);
snprintf(lat_string,
sizeof(lat_string),
"%02u%08.5f,%c",
(unsigned) deg,
double((deg - int(deg)) * 60),
loc.lat < 0 ? 'S' : 'N');
// format longitude
char lng_string[14];
deg = fabsf(loc.lng * 1.0e-7f);
snprintf(lng_string,
sizeof(lng_string),
"%03u%08.5f,%c",
(unsigned) deg,
double((deg - int(deg)) * 60),
loc.lng < 0 ? 'W' : 'E');
// format GGA message
char* gga = nullptr;
int16_t gga_res = asprintf(&gga,
"$GPGGA,%s,%s,%s,%01d,%02d,%04.1f,%07.2f,M,0.0,M,,",
tstring,
lat_string,
lng_string,
pos_valid ? 1 : 0,
pos_valid ? 6 : 3,
2.0,
loc.alt * 0.01f);
char gga_end[6];
snprintf(gga_end, sizeof(gga_end), "*%02X\r\n", (unsigned) _nmea_checksum(gga));
// get speed
Vector2f speed = ahrs.groundspeed_vector();
float speed_knots = norm(speed.x, speed.y) * M_PER_SEC_TO_KNOTS;
float heading = wrap_360(degrees(atan2f(speed.x, speed.y)));
// format RMC message
char* rmc = nullptr;
int16_t rmc_res = asprintf(&rmc,
"$GPRMC,%s,%c,%s,%s,%.2f,%.2f,%s,,",
tstring,
pos_valid ? 'A' : 'V',
lat_string,
lng_string,
speed_knots,
heading,
dstring);
char rmc_end[6];
snprintf(rmc_end, sizeof(rmc_end), "*%02X\r\n", (unsigned) _nmea_checksum(rmc));
// send to all NMEA output ports
for (uint8_t i = 0; i < _num_outputs; i++) {
if (gga_res != -1) {
_uart[i]->write(gga);
_uart[i]->write(gga_end);
}
if (rmc_res != -1) {
_uart[i]->write(rmc);
_uart[i]->write(rmc_end);
}
}
if (gga_res != -1) {
free(gga);
}
if (rmc_res != -1) {
free(rmc);
}
_last_sent = now;
}
#endif // !HAL_MINIMIZE_FEATURES && AP_AHRS_NAVEKF_AVAILABLE

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libraries/AP_NMEA_Output/AP_NMEA_Output.h Normal file
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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
*/
#pragma once
#include <AP_HAL/AP_HAL.h>
#include <AP_AHRS/AP_AHRS.h>
#if !HAL_MINIMIZE_FEATURES && AP_AHRS_NAVEKF_AVAILABLE
#include <AP_SerialManager/AP_SerialManager.h>
class AP_NMEA_Output {
public:
static AP_NMEA_Output* probe();
/* Do not allow copies */
AP_NMEA_Output(const AP_NMEA_Output &other) = delete;
AP_NMEA_Output &operator=(const AP_NMEA_Output&) = delete;
void update();
private:
AP_NMEA_Output();
uint8_t _nmea_checksum(const char *str);
static AP_NMEA_Output* _singleton;
uint8_t _num_outputs;
AP_HAL::UARTDriver* _uart[SERIALMANAGER_NUM_PORTS];
uint16_t _last_sent;
};
#endif // !HAL_MINIMIZE_FEATURES && AP_AHRS_NAVEKF_AVAILABLE