/* Periodically called callback used to add samples to the DAC.  */
static void fill_timer_cb(struct music_player_t *self_p)
/* Periodically called callback used to add samples to the DAC.  */
static void fill_timer_cb(struct music_player_t *self_p)
{
    uint32_t mask;
    mask = EVENT_TIMEOUT;
    event_write_isr(&self_p->event, &mask, sizeof(mask));
}