switch_leds
switch_leds(ctrl, num_of_slots, &work_LED, 0);
switch_leds(ctrl, num_of_slots, &work_LED, 1);
switch_leds(ctrl, num_of_slots, &work_LED, 0);
switch_leds(ctrl, num_of_slots, &work_LED, 1);
switch_leds(ctrl, num_of_slots, &work_LED, 0);
switch_leds(ctrl, num_of_slots, &work_LED, 1);
switch_leds(ctrl, num_of_slots, &work_LED, 0);
switch_leds(ctrl, num_of_slots, &work_LED, 1);