channel_port_alloc function

[Stas]

I'm going through pin_change_int example and can't understand how we tell controller where locate the function for our event. Probably it occures in channel_port_alloc that locate inside nrf_drv_gpiote_in_init(PIN_IN, &in_config, in_pin_handler); but where we point the function pointer... it seems we just fill out m_cb structure

static int8_t channel_port_alloc(uint32_t pin,nrf_drv_gpiote_evt_handler_t handler, bool channel)
{
    int8_t channel_id = NO_CHANNELS;
    uint32_t i;

    uint32_t start_idx = channel ? 0 : GPIOTE_CH_NUM; //(0, 8)
    uint32_t end_idx = channel ? GPIOTE_CH_NUM : (GPIOTE_CH_NUM + GPIOTE_CONFIG_NUM_OF_LOW_POWER_EVENTS);// (8, 9)
    //critical section
	 
    for (i = start_idx; i < end_idx; i++)
    {
        if (m_cb.handlers[i] == FORBIDDEN_HANDLER_ADDRESS)
        {
            pin_in_use_by_te_set(pin, i, handler, channel);
            channel_id = i;
            break;
        }
    }
    //critical section
    return channel_id;
}



_STATIC_INLINE void pin_in_use_by_te_set(uint32_t pin,
                                          uint32_t channel_id,
                                          nrf_drv_gpiote_evt_handler_t handler,
                                          bool is_channel)
{
    m_cb.pin_assignments[pin] = channel_id;
    m_cb.handlers[channel_id] = handler;
    if (!is_channel)
    {
        m_cb.port_handlers_pins[channel_id - GPIOTE_CH_NUM] = (int8_t)pin;
    }
}

[Ole Bauck]

You should read the GPIOTE and GPIO chapters in the Product Specification.

Here is also some code that will set up PORT event on button 1 and IN event on button 2:

void gpiote_int_init()
{
    nrf_gpio_cfg_sense_input(BUTTON_1, NRF_GPIO_PIN_PULLUP, NRF_GPIO_PIN_SENSE_LOW);
    nrf_gpio_cfg_input(BUTTON_2, NRF_GPIO_PIN_PULLUP);

    NRF_GPIOTE->CONFIG[0] =  (GPIOTE_CONFIG_MODE_Event       << GPIOTE_CONFIG_MODE_Pos)
                            |(GPIOTE_CONFIG_POLARITY_HiToLo << GPIOTE_CONFIG_POLARITY_Pos)
                            |(BUTTON_2                      << GPIOTE_CONFIG_PSEL_Pos);
    
    NRF_GPIOTE->EVENTS_IN[0] = 0;
    NRF_GPIOTE->EVENTS_PORT = 0;
    
    NRF_GPIOTE->INTENSET = (GPIOTE_INTENSET_PORT_Enabled << GPIOTE_INTENSET_PORT_Pos);
    NRF_GPIOTE->INTENSET = (GPIOTE_INTENSET_IN0_Enabled << GPIOTE_INTENSET_IN0_Pos);
    
    NVIC_SetPriority(GPIOTE_IRQn, APP_IRQ_PRIORITY_LOW);
    NVIC_EnableIRQ(GPIOTE_IRQn);
}

void GPIOTE_IRQHandler(void)
{
    if(NRF_GPIOTE->EVENTS_PORT != 0)
    {
        NRF_GPIOTE->EVENTS_PORT = 0;
        //code on PORT event
    }
    if(NRF_GPIOTE->EVENTS_IN[0] != 0)
    {
        NRF_GPIOTE->EVENTS_IN[0] = 0;
        //code on IN[0] event
    } 
}

Call gpiote_int_init() in main (before while loop). The IRQ handler will be called when one of the buttons is pressed. nrf_gpio_cfg_.. functions set up the GPIO register, go to the definition of this functions to see how they set up the GPIO register. Hope this helps you understand how it works.