rem: timer_id timer = timer_add(30 * SECONDS, (TimerCallback) opn_connect, &timer);
add: timer_connect = timer_add(30 * SECONDS, (TimerCallback) opn_connect, NULL);
context: void main_timer(){	timer_id timer = timer_add(30 * SECONDS,                               (TimerCallback) opn_connect, &timer);}