[nRF52832] Unable to configure InterruptIn + PullDown on P0_1

[luoman]

Hello !

I am currently working on a custom board on which I don't need 32.768kHz. I want to use P0_1 as an interruption pin connected to a pushbutton. The button is connected to VCC so when it's pressed it imposes a high logical level on the GPIO. I configured configured the GPIO to enable the internal pull-down so the low logical level is supposed to be forced when pushbutton is not pressed.

bool pressed = false;
 
void pushbutton1_handler( void )
{
   pressed = true;
}
 
InterruptIn bp1( P0_1 );
 
int main( void )
{
   bp1.rise( &pushbutton1_handler );
   bp1.mode( PullDown );
 
   while(1) {
 
      if( pressed == true ) {
         LOG("pressed\r\n");
         pressed = false;
      }
   }
}

I run this code and measure the voltage on P0_1, which is supposed to be grounded, but I measure 3.3V

Is there a known issue related to this situation ?

Thanks

[MartinBL]

I haven't heard of this before. Have you tried to use a different GPIO pin to see if it is related to the P0.01 pin in particular? Is it possible that the pin is somehow shorted to VCC?

[luoman]

Hello ! To ensure that the pin is not shorted to VCC, I did the exact same test on the NRF52_DK board (I cut SB1 and shorted SB3 to configure P0_1 as a standard GPIO). The result is exactly the same, and I'm still measuring 3.3V on the GPIO. Is it possible that this pin cannot be configure as InterruptIn ?

[MartinBL]

I'm not able to reproduce it. The GPIO with pulldown seems to work fine on my nRF52 DK. If I e.g. configure the P0.01 as input and then alternate between using a pullup or pulldown I can see that the pin is pulled high and low accordingly. Can you upload the .hex file that you use?

[luoman]

Did you try to configure it as an interrupt pin, or did you only try digital input ? Here is the .hex file corresponding to the code I sent : https://ufile.io/w0m75

[MartinBL]

I tried this:

nrf_gpio_cfg(
    1,
    NRF_GPIO_PIN_DIR_INPUT,
    NRF_GPIO_PIN_INPUT_CONNECT,
    NRF_GPIO_PIN_PULLDOWN,
    NRF_GPIO_PIN_S0S1,
    NRF_GPIO_PIN_NOSENSE);

NRF_GPIOTE->CONFIG[0] =    (GPIOTE_CONFIG_MODE_Event << GPIOTE_CONFIG_MODE_Pos) | 
                        (1 << GPIOTE_CONFIG_PSEL_Pos) |
                        (GPIOTE_CONFIG_POLARITY_LoToHi << GPIOTE_CONFIG_POLARITY_Pos) |
                        (GPIOTE_CONFIG_OUTINIT_Low << GPIOTE_CONFIG_OUTINIT_Pos);

and it worked as it should. I also tried your hex file and saw the same thing as you. Maybe the mbed driver doesn't allow using pin 1 or 2? Did you try forcing the pin high and low externally? Does that trigger interrupts?