ardupilot/ArduCopter/events.pde

// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-

/*
 *       This event will be called when the failsafe changes
 *       boolean failsafe reflects the current state
 */
static void failsafe_radio_on_event()
{
    // if motors are not armed there is nothing to do
    if( !motors.armed() ) {
        return;
    }

    // This is how to handle a failsafe.
    switch(control_mode) {
        case STABILIZE:
        case ACRO:
            // if throttle is zero disarm motors
            if (g.rc_3.control_in == 0) {
                init_disarm_motors();
            }else if(ap.home_is_set == true && home_distance > g.waypoint_radius) {
                set_mode(RTL);
            }else{
                // We have no GPS or are very close to home so we will land
                set_mode(LAND);
            }
            break;
        case AUTO:
            // failsafe_throttle is 1 do RTL, 2 means continue with the mission
            if (g.failsafe_throttle == FS_THR_ENABLED_ALWAYS_RTL) {
                if(home_distance > g.waypoint_radius) {
                    set_mode(RTL);
                }else{
                    // We are very close to home so we will land
                    set_mode(LAND);
                }
            }
            // if failsafe_throttle is 2 (i.e. FS_THR_ENABLED_CONTINUE_MISSION) no need to do anything
            break;
        default:
            if(ap.home_is_set == true && home_distance > g.waypoint_radius) {
                set_mode(RTL);
            }else{
                // We have no GPS or are very close to home so we will land
                set_mode(LAND);
            }
            break;
    }

    // log the error to the dataflash
    Log_Write_Error(ERROR_SUBSYSTEM_FAILSAFE_RADIO, ERROR_CODE_FAILSAFE_OCCURRED);

}

// failsafe_off_event - respond to radio contact being regained
// we must be in AUTO, LAND or RTL modes
// or Stabilize or ACRO mode but with motors disarmed
static void failsafe_radio_off_event()
{
    // no need to do anything except log the error as resolved
    // user can now override roll, pitch, yaw and throttle and even use flight mode switch to restore previous flight mode
    Log_Write_Error(ERROR_SUBSYSTEM_FAILSAFE_RADIO, ERROR_CODE_FAILSAFE_RESOLVED);
}

static void low_battery_event(void)
{
    // failsafe check
    if (g.failsafe_battery_enabled && !ap.low_battery && motors.armed()) {
        switch(control_mode) {
            case STABILIZE:
            case ACRO:
                // if throttle is zero disarm motors
                if (g.rc_3.control_in == 0) {
                    init_disarm_motors();
                }else{
                    set_mode(LAND);
                }
                break;
            case AUTO:
                if(ap.home_is_set == true && home_distance > g.waypoint_radius) {
                    set_mode(RTL);
                }else{
                    // We have no GPS or are very close to home so we will land
                    set_mode(LAND);
                }
                break;
            default:
                set_mode(LAND);
                break;
        }
    }

    // set the low battery flag
    set_low_battery(true);

    // warn the ground station and log to dataflash
    gcs_send_text_P(SEVERITY_LOW,PSTR("Low Battery!"));
    Log_Write_Error(ERROR_SUBSYSTEM_FAILSAFE_BATT, ERROR_CODE_FAILSAFE_OCCURRED);

#if COPTER_LEDS == ENABLED
    if ( bitRead(g.copter_leds_mode, 3) ) {         // Only Activate if a battery is connected to avoid alarm on USB only
        piezo_on();
    }
#endif // COPTER_LEDS
}

// failsafe_gps_check - check for gps failsafe
static void failsafe_gps_check()
{
    uint32_t last_gps_update_ms;

    // return immediately if gps failsafe is disabled
    if( !g.failsafe_gps_enabled ) {
        return;
    }

    // calc time since last gps update
    last_gps_update_ms = millis() - g_gps->last_fix_time;

    // check if all is well
    if( last_gps_update_ms < FAILSAFE_GPS_TIMEOUT_MS) {
        // check for recovery from gps failsafe
        if( ap.failsafe_gps ) {
            failsafe_gps_off_event();
            set_failsafe_gps(false);
        }
        return;
    }

    // do nothing if gps failsafe already triggered or motors disarmed
    if( ap.failsafe_gps || !motors.armed()) {
        return;
    }

    // GPS failsafe event has occured
    // update state, warn the ground station and log to dataflash
    set_failsafe_gps(true);
    gcs_send_text_P(SEVERITY_LOW,PSTR("Lost GPS!"));
    Log_Write_Error(ERROR_SUBSYSTEM_FAILSAFE_GPS, ERROR_CODE_FAILSAFE_OCCURRED);

    // take action based on flight mode
    switch(control_mode) {
        // for modes that do not require gps, do nothing
        case STABILIZE:
        case ACRO:
        case ALT_HOLD:
        case OF_LOITER:
            // do nothing
            break;

        // modes requiring GPS force a land
        case AUTO:
        case GUIDED:
        case LOITER:
        case RTL:
        case CIRCLE:
        case POSITION:
            // We have no GPS or are very close to home so we will land
            set_mode(LAND);
            break;

        case LAND:
            // if we're already landing do nothing
            break;
    }
}

// failsafe_gps_off_event - actions to take when GPS contact is restored
static void failsafe_gps_off_event(void)
{
    // log recovery of GPS in logs?
    Log_Write_Error(ERROR_SUBSYSTEM_FAILSAFE_GPS, ERROR_CODE_FAILSAFE_RESOLVED);
}

static void update_events()     // Used for MAV_CMD_DO_REPEAT_SERVO and MAV_CMD_DO_REPEAT_RELAY
{
    if(event_repeat == 0 || (millis() - event_timer) < event_delay)
        return;

    if(event_repeat != 0) {             // event_repeat = -1 means repeat forever
        event_timer = millis();

        if (event_id >= CH_5 && event_id <= CH_8) {
            if(event_repeat%2) {
                hal.rcout->write(event_id, event_value);                 // send to Servos
            } else {
                hal.rcout->write(event_id, event_undo_value);
            }
        }

        if  (event_id == RELAY_TOGGLE) {
            relay.toggle();
        }
        if (event_repeat > 0) {
            event_repeat--;
        }
    }
}