ardupilot/libraries/AP_GPS/AP_GPS_PX4.cpp

99 lines
3.8 KiB
C++

// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
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/>.
*/
// GPS proxy driver for APM on PX4 platforms
//
// This driver subscribes on PX4s vehicle_gps_position topic and presents the data received to APM.
// The publisher could be an UAVCAN GNSS module like http://docs.zubax.com/Zubax_GNSS, or any other GNSS
// hardware supported by the PX4 ecosystem.
//
// Code by Holger Steinhaus
#include <AP_HAL/AP_HAL.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_PX4
#include "AP_GPS_PX4.h"
#include <uORB/uORB.h>
#include <cmath>
extern const AP_HAL::HAL& hal;
AP_GPS_PX4::AP_GPS_PX4(AP_GPS &_gps, AP_GPS::GPS_State &_state, AP_HAL::UARTDriver *_port) :
AP_GPS_Backend(_gps, _state, _port)
{
_gps_sub = orb_subscribe(ORB_ID(vehicle_gps_position));
}
#define MS_PER_WEEK 7*24*3600*1000LL
#define DELTA_POSIX_GPS_EPOCH 315964800LL*1000LL
#define LEAP_MS_GPS_2014 16*1000LL
// update internal state if new GPS information is available
bool
AP_GPS_PX4::read(void)
{
bool updated = false;
orb_check(_gps_sub, &updated);
if (updated) {
if (OK == orb_copy(ORB_ID(vehicle_gps_position), _gps_sub, &_gps_pos)) {
state.last_gps_time_ms = AP_HAL::millis();
state.status = (AP_GPS::GPS_Status) (_gps_pos.fix_type | AP_GPS::NO_FIX);
state.num_sats = _gps_pos.satellites_used;
state.hdop = uint16_t(_gps_pos.eph*100.0f + .5f);
if (_gps_pos.fix_type >= 2) {
state.location.lat = _gps_pos.lat;
state.location.lng = _gps_pos.lon;
state.location.alt = _gps_pos.alt/10;
state.ground_speed = _gps_pos.vel_m_s;
state.ground_course_cd = wrap_360_cd(degrees(_gps_pos.cog_rad)*100);
state.hdop = _gps_pos.eph*100;
// convert epoch timestamp back to gps epoch - evil hack until we get the genuine
// raw week information (or APM switches to Posix epoch ;-) )
uint64_t epoch_ms = uint64_t(_gps_pos.time_utc_usec/1000.+.5);
uint64_t gps_ms = epoch_ms - DELTA_POSIX_GPS_EPOCH + LEAP_MS_GPS_2014;
state.time_week = uint16_t(gps_ms / uint64_t(MS_PER_WEEK));
state.time_week_ms = uint32_t(gps_ms - uint64_t(state.time_week)*MS_PER_WEEK);
if (_gps_pos.time_utc_usec == 0) {
// This is a work-around for https://github.com/PX4/Firmware/issues/1474
// reject position reports with invalid time, as APM adjusts it's clock after the first lock has been aquired
state.status = AP_GPS::NO_FIX;
}
}
if (_gps_pos.fix_type >= 3) {
state.have_vertical_velocity = _gps_pos.vel_ned_valid;
state.velocity.x = _gps_pos.vel_n_m_s;
state.velocity.y = _gps_pos.vel_e_m_s;
state.velocity.z = _gps_pos.vel_d_m_s;
state.speed_accuracy = _gps_pos.s_variance_m_s;
state.have_speed_accuracy = true;
}
else {
state.have_vertical_velocity = false;
}
}
}
return updated;
}
#endif