RE: how to make a Pulse with Timer1

Ole Morten — Fri, 04 Oct 2013 13:37:55 GMT

Please see my edit. I haven't tested this, but it should at least make it clear how you could do it.

RE: how to make a Pulse with Timer1

Nils Minor — Wed, 02 Oct 2013 12:46:52 GMT

Hi thank you Ole, This i a good example. I Understand what happens in this code. But how is it when i want to call a Method every CC[0] or CC[1] happens?

RE: how to make a Pulse with Timer1

Ole Morten — Wed, 02 Oct 2013 12:28:05 GMT

The function you want should be achievable with using just the GPIOTE, a TIMER and the PPI. Please see the attached main-file, which looks something like this:


    ...
    NRF_CLOCK->TASKS_HFCLKSTART = 1;
    
    NRF_TIMER0->CC[0] = 100;
    NRF_TIMER0->CC[1] = 250000;
    NRF_TIMER0->PRESCALER = 4;
    NRF_TIMER0->SHORTS = TIMER_SHORTS_COMPARE1_CLEAR_Enabled << TIMER_SHORTS_COMPARE1_CLEAR_Pos;
    
    nrf_gpiote_task_config(0, OUT_PIN_NUMBER, NRF_GPIOTE_POLARITY_TOGGLE, NRF_GPIOTE_INITIAL_VALUE_HIGH);
    
    NRF_PPI->CH[0].EEP = (uint32_t) &NRF_TIMER0->EVENTS_COMPARE[0];
    NRF_PPI->CH[0].TEP = (uint32_t) &NRF_GPIOTE->TASKS_OUT[0];
    NRF_PPI->CH[1].EEP = (uint32_t) &NRF_TIMER0->EVENTS_COMPARE[1];
    NRF_PPI->CH[1].TEP = (uint32_t) &NRF_GPIOTE->TASKS_OUT[0];
    NRF_PPI->CHENSET = PPI_CHENSET_CH0_Enabled << PPI_CHENSET_CH0_Pos | 
                       PPI_CHENSET_CH1_Enabled << PPI_CHENSET_CH1_Pos;
    
    NRF_TIMER0->TASKS_START = 1;

    ...

Edit: If you want interrupts, it should be sufficient to enable interrupts on the COMPARE events, and then implement a TIMER0_IRQHandler. I haven't tested this code, but it should be something like this:



void TIMER0_IRQHandler(void)
{
    if (NRF_TIMER0->EVENTS_COMPARE[0] == 1)
    {
        NRF_TIMER0->EVENTS_COMPARE[0] = 0;
        ...
    } 
    if (NRF_TIMER0->EVENTS_COMPARE[1] == 1)
    {
        NRF_TIMER0->EVENTS_COMPARE[1] = 0;
        ...
    }
}
...
    NRF_TIMER0->INTENSET = TIMER_INTENSET_COMPARE0_Enabled << TIMER_INTENSET_COMPARE0_Pos |
                           TIMER_INTENSET_COMPARE1_Enabled << TIMER_INTENSET_COMPARE1_Pos;
    NVIC_EnableIRQ(TIMER0_IRQn);
...

main.c