pin change interrupt

#include "nrf.h"
#include "boards.h"
 
#define LED 22
#define BUTTON 16
 
 
void GPIOTE_IRQHandler(void)
{
    // Event causing the interrupt must be cleared.
    if ((NRF_GPIOTE->EVENTS_IN[0] == 1) &&
        (NRF_GPIOTE->INTENSET & GPIOTE_INTENSET_IN0_Msk))
    {
        NRF_GPIOTE->EVENTS_IN[0] = 0;
        nrf_gpio_pin_toggle(LED);
    }
}
 
static void gpio_init(void)
{
    nrf_gpio_cfg_output(LED);
    nrf_gpio_cfg_input(BUTTON, NRF_GPIO_PIN_PULLUP);
    nrf_gpio_pin_clear(LED);
    
    // Enable interrupt:
    NVIC_EnableIRQ(GPIOTE_IRQn);
    NRF_GPIOTE->CONFIG[0] = (GPIOTE_CONFIG_POLARITY_Toggle << GPIOTE_CONFIG_POLARITY_Pos)
                            | (BUTTON << GPIOTE_CONFIG_PSEL_Pos)
                            | (GPIOTE_CONFIG_MODE_Event << GPIOTE_CONFIG_MODE_Pos);
    NRF_GPIOTE->INTENSET = GPIOTE_INTENSET_IN0_Set << GPIOTE_INTENSET_IN0_Pos;
}
 
int main(void)
{
    gpio_init();
 
    while (true)
    {
        // Do nothing.
    }
}