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

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

Simonr — Fri, 13 Dec 2024 12:13:35 GMT

There should not be an issue with using P0.18 for SPI purposes. There must be something with how the SPI is set up if you don't get it to work on any of the pins. Please share how it's set up in the device tree. I recommend checking out the lesson on SPI we have in the DevAcademy that should show you step by step how to create an SPI project from the get go.

Best regards,

Simon

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

DX_HK — Thu, 12 Dec 2024 13:09:33 GMT

I don't know the exact cause, but I was able to use P0.18 as a GPIO.
Apparently, in my environment, when building with the GUI, code changes are sometimes not reflected.
It works fine by building with the CLI.

However, my real goal is to assign it to the SPI MOSI pin, which is still not working.
SPI is not working on other ports either, so I will look into it a bit more.
Also, is it possible to use P0.18 as the SPI MOSI pin?

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

Susheel Nuguru — Thu, 12 Dec 2024 12:10:26 GMT

Should have taken this into effect with NCSv2.7.0.
Can you check in your build folder project_folder\build\sample_name\zephyr.dts and see the &uicr node has the gpio-as-nreset removed.

Since this is pin 18 you are using, make sure that you have right configuration of pin 18 in your pinctrl.

How are you testing that the nreset is still enabled using this gpio?

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

DX_HK — Wed, 11 Dec 2024 12:17:12 GMT

/delete-property/ gpio-as-nreset

I added it, but it had the same effect.
I also edited the dts file of nrf52833dk (I know it's an inappropriate method) and deleted the property.
How can I analyze this problem?

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

Simonr — Wed, 11 Dec 2024 11:55:28 GMT

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

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

DX_HK — Tue, 10 Dec 2024 09:04:43 GMT

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

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

Simonr — Mon, 09 Dec 2024 13:26:48 GMT

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

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

DX_HK — Mon, 09 Dec 2024 08:44:54 GMT

Is that description incorrect?

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

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

Simonr — Fri, 06 Dec 2024 14:31:10 GMT

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