ardupilot/AntennaTracker/sensors.cpp

#include "Tracker.h"

/*
  update INS and attitude
 */
void Tracker::update_ahrs()
{
    ahrs.update();
}

/*
  read and update compass
 */
void Tracker::update_compass(void)
{
    compass.read();
}

// Save compass offsets
void Tracker::compass_save() {
    if (AP::compass().available() &&
        compass.get_learn_type() >= Compass::LEARN_INTERNAL &&
        !hal.util->get_soft_armed()) {
        compass.save_offsets();
    }
}

/*
  read the GPS
 */
void Tracker::update_GPS(void)
{
    gps.update();

    static uint32_t last_gps_msg_ms;
    static uint8_t ground_start_count = 5;
    if (gps.last_message_time_ms() != last_gps_msg_ms && 
        gps.status() >= AP_GPS::GPS_OK_FIX_3D) {
        last_gps_msg_ms = gps.last_message_time_ms();
        
        if (ground_start_count > 1) {
            ground_start_count--;
        } else if (ground_start_count == 1) {
            // We countdown N number of good GPS fixes
            // so that the altitude is more accurate
            // -------------------------------------
            if (current_loc.lat == 0 && current_loc.lng == 0) {
                ground_start_count = 5;

            } else {
                // Now have an initial GPS position
                // use it as the HOME position in future startups
                current_loc = gps.location();
                IGNORE_RETURN(set_home(current_loc));
                ground_start_count = 0;
            }
        }
    }
}

void Tracker::handle_battery_failsafe(const char* type_str, const int8_t action)
{
    // NOP
    // useful failsafes in the future would include actually recalling the vehicle
    // that is tracked before the tracker loses power to continue tracking it
}