Pulse generation on pin incorrect when sd in advertising mode

Question

Hi,

I am trying to generate a constant 250ms pulse on a certain pin:

  NRF_TIMER0->MODE      = TIMER_MODE_MODE_Timer;
  NRF_TIMER0->BITMODE   = TIMER_BITMODE_BITMODE_16Bit;
  NRF_TIMER0->PRESCALER = 4;
  NRF_TIMER0->CC[0] = 25000;
  NRF_TIMER0->SHORTS = TIMER_SHORTS_COMPARE0_CLEAR_Msk;
  int chNo = 0;
  nrf_gpiote_task_config(chNo, PIN_NO, NRF_GPIOTE_POLARITY_TOGGLE, NRF_GPIOTE_INITIAL_VALUE_HIGH);

  sd_ppi_channel_assign(chNo, &(NRF_TIMER0->EVENTS_COMPARE[0]), &NRF_GPIOTE->TASKS_OUT[chNo]);
  sd_ppi_channel_enable_set(1 << chNo);

  NRF_TIMER0->TASKS_START = 1;

but I see that the pulse is about 1s long when the BLE is in advertise mode. As soon as the device is connected with a host, the pulse generator behaves correctly. I am really puzzled about this behavior. Any help is appreciated!

Thanks! florin

Dan Danknick · Accepted Answer

You may want to refer to the SD spec, specifically "Table 18 Peripheral protection and usage by SoftDevice." The SD owns TIMER0 so I'd say that you're lucky your code works at all. :) 
 Switch to TIMER1 and you should be fine. 
 Dan