Trouble getting GPIOTE event to fire directly manipulating registers

Question

Hi there,

I'm working on something with hard real-time requirements - for this and a number of other reasons, I'm writing directly to the registers.

I'm trying to generate an interrupt when pressing SW1 on the nRF52840-DONGLE board (connect to P1.06), however, I can't get it to fire. Code is below:

void GPIOTE_IRQHandler()
{
    int i = 1;    
}

void setup_button()
{
    const uint32_t CHAN = 3;
    NRF_P1->PIN_CNF[6] = ((uint32_t)GPIO_PIN_CNF_DIR_Input << GPIO_PIN_CNF_DIR_Pos)
                       | ((uint32_t)GPIO_PIN_CNF_INPUT_Connect << GPIO_PIN_CNF_INPUT_Pos)
                       | ((uint32_t)GPIO_PIN_CNF_PULL_Pullup << GPIO_PIN_CNF_PULL_Pos)
                       | ((uint32_t)GPIO_PIN_CNF_DRIVE_S0S1 << GPIO_PIN_CNF_DRIVE_Pos)
                       | ((uint32_t)NRF_GPIO_PIN_NOSENSE << GPIO_PIN_CNF_SENSE_Pos);

    NRF_GPIOTE->CONFIG[CHAN] = 
        GPIOTE_CONFIG_MODE_Event << GPIOTE_CONFIG_MODE_Pos | 
        GPIOTE_CONFIG_POLARITY_Toggle << GPIOTE_CONFIG_POLARITY_Pos | 
        NRF_GPIO_PIN_MAP(1, 6) << GPIOTE_CONFIG_PSEL_Pos;
    
    NRF_GPIOTE->INTENSET |= 0x01UL<<CHAN;
}

int main(void)
{


    setup_button();

    while (true)
    {
        __WFI();
        int i = 1;
    }
}

I've run the above code and put a breakpoint on both lines 3 or 32; neither get hit when pressing the button. I've set it as a debug build; looking at the assembly, the "int i = 1" instructions are definitely compiled. I've also tried removing the __WFI() from the main loop and let it run flat out - no difference.

Clearly I'm missing something, but from the doco it's not clear what it is. Any guidance is appreciate. Thanks!

Vidar Berg · Accepted Answer

Hi, 
 You will need to call NVIC_EnableIRQ(GPIOTE_IRQn) to enable the interrupt in the NVIC as well. Also, remember to clear the GPIOTE event from your interrupt handler. Otherwise the interrupt will be triggered again as soon as you exit the handler. 
 //Clearing IN event 
 NRF_GPIOTE->EVENTS_IN[CHANNEL_NUM] = 0;

Trouble getting GPIOTE event to fire directly manipulating registers

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