nRF52833 (P0.18) nRST cannot be used as GPIO

[DX_HK]

I am using nRF52833DK, zephyr v2.7.0.

I want to disable hardware nRST to use P0.18 as GPIO.

What I did

Added to Kconfig : CONFIG_GPIO_AS_PINRESET=n

Removed : gpio-as-nreset

But it is still enabled.

When I check UICR,

nrfjprog --family NRF52 --memrd 0x10001200

0x10001200: 00000012

It seems to be attached.

Please tell me how to use nRST (P0.18) as GPIO.

[Simonr]

Hi

As of NCS v2.7.0, the CONFIG_GPIO_AS_PINRESET was deprecated I'm afraid, and to set the reset pin as a GPIO now, you should instead do so in devicetree by setting the following:

&uicr { gpio-as-nreset; };

Best regards,

Simon

[DX_HK]

Is that description incorrect?

docs.zephyrproject.org/.../nordic,nrf-uicr.html
> When enabled, this property will configure the reset GPIO as nRESET.

[Simonr]

Hi

Yes, so this will need to be disabled to let you use P0.18 as a GPIO, and not as the reset button. Sorry  about any confusion there.

Best regards,

Simon

[DX_HK]

Could you please provide an example of using nrf52833dk to disable nRST and use it as a GPIO?

[Simonr]

Hi

The simplest thing to do would probably be to add the following in the .overlay file of your project, as it is set as a reset pin by default in most board files by default and likely is for you as well. I realize I didn't show how to remove a set device tree setting:

&uicr {
        /delete-property/ gpio-as-nreset;
    };

PS: If you have your own board files for your custom board you can also just remove gpio-as-nreset from the .dts file for your custom board.

Best regards,

Simon