LPP » INSTRU » Solar Orbiter LFR » LFR-FSW

On peut expliquer ce comportement. Au redémarrage de SocExplorer et du soft, l'IP SpaceWire n'est pas redémarrée et donc la dernière valeur valide est toujours dans les registres du FPGA. A la fin de la tâche INIT, le timer qui permet de détecter un timecode_missing démarre et arrive à échéance 2s après. La routine compare le dernier timecode valide avec une valeur courante interne au soft de vol et identifie un timecode_invalid.

Dans fsw_init.c:

rtems_task Init( rtems_task_argument ignored )
{

[...]

    // start the timer to detect a missing spacewire timecode
    // the timeout is larger because the spw IP needs to receive several valid timecodes before generating a tickout
    // if a tickout is generated, the timer is restarted
    status = rtems_timer_fire_after( timecode_timer_id, TIMECODE_TIMER_TIMEOUT_INIT, timecode_timer_routine, NULL );

    grspw_timecode_callback = &timecode_irq_handler;

    status = rtems_task_delete(RTEMS_SELF);

}

Dans fsw_spacewire.c:

rtems_timer_service_routine timecode_timer_routine( rtems_id timer_id, void *user_data )
{
    static unsigned char initStep = 1;

    unsigned char currentTimecodeCtr;

    currentTimecodeCtr = (unsigned char) (grspwPtr[0] & TIMECODE_MASK);

    if (initStep == 1)
    {
        if (currentTimecodeCtr == previousTimecodeCtr)
        {
            //************************
            // HK_LFR_TIMECODE_MISSING
            // the timecode value has not changed, no valid timecode has been received, the timecode is MISSING
            increase_unsigned_char_counter( &housekeeping_packet.hk_lfr_timecode_missing );
            update_hk_lfr_last_er_fields( RID_LE_LFR_TIMEC, CODE_MISSING );
        }
        else if (currentTimecodeCtr == (previousTimecodeCtr+1))
        {
            // the timecode value has changed and the value is valid, this is unexpected because
            // the timer should not have fired, the timecode_irq_handler should have been raised
        }
        else
        {
            //************************
            // HK_LFR_TIMECODE_INVALID
            // the timecode value has changed and the value is not valid, no tickout has been generated
            // this is why the timer has fired
            increase_unsigned_char_counter( &housekeeping_packet.hk_lfr_timecode_invalid );
            update_hk_lfr_last_er_fields( RID_LE_LFR_TIMEC, CODE_INVALID );
        }
    }
    else
    {
        initStep = 1;
        //************************
        // HK_LFR_TIMECODE_MISSING
        increase_unsigned_char_counter( &housekeeping_packet.hk_lfr_timecode_missing );
        update_hk_lfr_last_er_fields( RID_LE_LFR_TIMEC, CODE_MISSING );
    }

    rtems_event_send( Task_id[TASKID_DUMB], RTEMS_EVENT_13 );
}