nRF 52 DK nrf_gpio_pin_read() always returning a 0 ?

[Garth]

Hi all,

I'm having an issue using the nrf_gpio_pin_read() function from the nrf_gpio.h file. When I call it every time after calling nrf_gpio_pin_toggle() on the same pin I am still always getting a 0 on my return. Any ideas as to why this is happening? Included code snippet below of usage.

nrf_gpio_pin_toggle(INDICATE_LED);
if(nrf_gpio_pin_read(INDICATE_LED)==0)
{
    for (uint32_t i = 0; i < length_on; i++)
    {
	    app_uart_put(L1ON[i]);
    }						
}
else  // NEVER GETTING IN HERE
{     // SHOULD BE WHEN PIN IS HIGH THOUGH
    for (uint32_t i = 0; i < length_off; i++)
    {
	    app_uart_put(L1OFF[i]);
    }
}

For clarification I am never making it into the else statement even though I should every other time the pin is toggled.

Any help would be appreciated, Thanks in advance!

[FormerMember]

My guess is that you did not configure the pin as an output before using it to toggle. You can do that by nrf_gpio_cfg_output(INDICATE_LED); Actually you can change the toggling driver implementation to suit you as follows so as to not read again:

__STATIC_INLINE bool nrf_gpio_pin_toggle(uint32_t pin_number)
{
    const uint32_t pin_bit   = 1UL << pin_number;
    const uint32_t pin_state = ((NRF_GPIO->OUT >> pin_number) & 1UL);

    if (pin_state == 0)
    {
        // Current state low, set high.
        NRF_GPIO->OUTSET = pin_bit;
        return true;
    }
    else
    {
        // Current state high, set low.
        NRF_GPIO->OUTCLR = pin_bit;
        return false;
    }
}

[Garth]

Ah I forgot to specify, but I do in fact configure the pin as output in my initialization, this is why I find the problem troubling. I do like your modification, though my problem is still not solved. Thanks for the quick response though!

[FormerMember]

Then either any other peripheral is controlling the pin. Or the pin is toggling or made high somewhere else. Best of luck.

[RK]

If you want to use the pin as an output AND an input, the normal nrf_gpio_cfg_output() function won't work for you because it sets the pin as an output and disables the input buffer, you can see that in nrf_gpio.h and read about connecting the input buffer in section 14.1 of the reference manual.

You can either set the pin up manually or call nrf_gpio_cfg_output() and then re-enable the input buffer with

NRF_GPIO->PIN_CNF[INDICATE_LED] |= (GPIO_PIN_CNF_INPUT_Connect << GPIO_PIN_CNF_INPUT_Pos);

[Blue_Alien]

Which pins are you using? I just found out that GPIO 9 and 10 can't be used on the dev board due to the hardware present for the NFC antenna.