Problem to using p0.18(RESET Pin) for GPIO

[butumout]

I'm using nrf52833 on custom board.

And I need to using RESET pin to GPIO for battery charging detection.

I found CONFIG_GPIO_AS_PINRESET is configuration RESET pin,

and if I undefined CONFIG_GPIO_AS_PINRESET, p0.18 pin will be working GPIO.

But, many of case was failed.

I think,

If I undefined CONFIG_GPIO_AS_PINRESET,

MCU was nothing to handling NRF_UICR->PSELRESET register.

But NRF_UICR->PSELRESET registor still configuration like RESET pin(like dummy data ).

So, even if CONFIG_GPIO_AS_PINRESET is undefined, MCU still working p0.18 pin is configuration by RESET pin.

That's why I think, it's need to setting NRF_UICR->PSELRESET register to disconnect(connect bit to set '1') when CONFIG_GPIO_AS_PINRESET is undefined.

[hyhkjiy]

Hi butumout,

You can check it useing nrfjprog tool.

First, erase user available code and UICR flash areas:

nrfjprog --eraseall

Now you can see the UICR flash of reset pin config as "FFFFFFFF FFFFFFFF":

nrfjprog --memrd 0x10001200 --w 32 --n 8
0x10001200: FFFFFFFF FFFFFFFF                     |........|

Next, to program your nrf52833 custom board, and see the reset pin config again.

If it is changed, it means that your program contains the definition of the CONFIG_GPIO_AS_PINRESET pin. Please check your APP project configuration and Bootloader project configuration.

Have a good day