RE: Which GPIO on nRf52382 can be configured as timer?

Øyvind Karlsen — Mon, 29 Feb 2016 09:44:48 GMT

Hi,

The following code using GPIOTE with PPI gives a 4MHz output on pin 18.

int main(void)
{
    nrf_gpio_range_cfg_output(18); //Configure pin 18 as output

    NRF_CLOCK->TASKS_HFCLKSTART = 1; //Start high frequency clock
    while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0)
    {
         //Wait for HFCLK to start
    }
    NRF_CLOCK->EVENTS_HFCLKSTARTED = 0; //Clear event
    
    
    //Configure GPIOTE to toggle pin 18 
    NRF_GPIOTE->CONFIG[0] = GPIOTE_CONFIG_MODE_Task << GPIOTE_CONFIG_MODE_Pos |
                            GPIOTE_CONFIG_POLARITY_Toggle << GPIOTE_CONFIG_POLARITY_Pos |
                            18 << GPIOTE_CONFIG_PSEL_Pos | 
                            GPIOTE_CONFIG_OUTINIT_Low << GPIOTE_CONFIG_OUTINIT_Pos;
    
    //Configure timer
    NRF_TIMER1->PRESCALER = 0;
    NRF_TIMER1->CC[0] = 2;  // Adjust the output frequency by adjusting the CC.
    NRF_TIMER1->SHORTS = TIMER_SHORTS_COMPARE0_CLEAR_Enabled << TIMER_SHORTS_COMPARE0_CLEAR_Pos;
    NRF_TIMER1->TASKS_START = 1;
    
    //Configure PPI
    NRF_PPI->CH[0].EEP = (uint32_t) &NRF_TIMER1->EVENTS_COMPARE[0];
    NRF_PPI->CH[0].TEP = (uint32_t) &NRF_GPIOTE->TASKS_OUT[0];
    
    NRF_PPI->CHENSET = PPI_CHENSET_CH0_Enabled << PPI_CHENSET_CH0_Pos;
    
    while (true)
    {
        // do nothing
    }
}

Because of pin crossbar almost any pin can be used, pin crossbar is essentially a mux that lets you chose any GPIO for any functionality. Please see the pin assignments for which pins are available for GPIO.

Best regards,

Øyvind