CONFIG_NFCT_PINS_AS_GPIOS=y doesn't work

[HFrg]

Hi,

I'm using an ISP2053 (nrf5340) chip on a custom board and debugging using the nrf5340dk. I'd like to use P0.02, P0.03 as part of an SPI bus.

I set up a simple experiment where I set `CONFIG_NFCT_PINS_AS_GPIOS=y` in my prj.conf and some code to toggle various pins that I can read on my board. P0.02 and P0.03 are always 0V and other pins toggle between 0V and 3V.

I believe the NFCPINS UICR register (0x00FF8028) should read 0xFFFFFFFE but using nrfjprog I can see that the register reads 0xFFFFFFFF:

```

nrfjprog --memrd 0x00FF8028

0x00FF8028: FFFFFFFF |....|

```

After I flash the code using nrfconnect vscode, I can set the register to 0xFFFFFFFE:

```

nrfjprog --memwr 0x00FF8028 --val 0xFFFFFFFE

Parsing parameters.

Writing.

nrfjprog --memrd 0x00FF8028

0x00FF8028: FFFFFFFE |....|

```

Now the NFC GPIO pins toggle on and off like the other pins.

Is this intended? It seems like CONFIG_NFCT_PINS_AS_GPIOS=y doesn't change the register value. I can see in Guiconfig, the `NFCT pins as GPIO` option is selected. Other options in prj.conf work.

I'd prefer not have to run `nrfjprog --memwr 0x00FF8028 --val 0xFFFFFFFE` when flashing. How do I diagnose the problem further?

I'm using ncs v2.1.1.

[Vidar Berg]

Hi,

Are you building the app for the non-secure domain? In that case, you will need to apply CONFIG_NFCT_PINS_AS_GPIOS=y to the image which runs in the secure domain instead. The reason for this is that the UICR register is only accessible from the secure domain.

Here is the startup file where the UICR register gets written: https://github.com/zephyrproject-rtos/hal_nordic/blob/master/nrfx/mdk/system_nrf5340_application.c#L178. Notice the if statement at line ~74 which checks if the code is run in secure domain or not. 

Best regards,

Vidar

[rdey]

Hi Vidar,

I am also having the same problem. I have set CONFIG_NFCT_PINS_AS_GPIOS=y and building the code for secure domain (nrf5340_cpuapp) for my custom board with nrf5340.

I found that the if statement on line 180 fails https://github.com/zephyrproject-rtos/hal_nordic/blob/master/nrfx/mdk/system_nrf5340_application.c#L180

What am I missing?

I am trying to use the P0.03 pin as an input pin. Detail of my issue can be found here

Thanks,

Rohan

[Vidar Berg]

Hi Rohan,

Please read the NFCPINS register value with your debugger to see if it has been configured or not.

With nrfjprog:

$ nrfjprog --memrd 0xff8028

[Surendra Amina]

Hi Vidar,

I am seeing the same issue on nrf5340. I cant use PIN 0.02 as GPIO.
$ nrfjprog --memrd 0xff8028
0x00FF8028: FFFFFFFE 

I have also set CONFIG_NFCT_PINS_AS_GPIOS=y

[Vidar Berg]

Please open a new ticket and include information about your setup (e.g. if you are using a nordic dev kit, or a custom board,..) and how you are trying to configure the pin.

Your UICR register readout confirms that the CONFIG_NFCT_PINS_AS_GPIOS=y setting was applied correctly, so that is not the problem in your case.

[creative.industry.ag]

Hello
I have the same issue. 
Does anybody solve this problem?

[Vidar Berg]

Please open a new ticket and include information about your setup, such as whether you are using a Nordic development kit or a custom board, what chip variant, and describe how you are attempting to configure the pin.

[Brett_G]

I just ran into a similar issue, where simple GPIO toggling of the NFC P0.03 was not working despite having CONFIG_NFCT_PINS_AS_GPIOS=y and seeing it being properly implemented in the UICR registers.

After a bit of debugging I found that the initialization of the GPIO was occurring within a SYS_INIT call, and calling the initialization function from main instead, would allow it to work fine.

Other non-nfc gpios called within that SYS_INIT worked fine, so it seems to only conflict with the NFC gpio configuration for some reason.

Hopefully this helps

[Nico7]

I'm not sure where SYS_INIT is. Could you please say how you solved this?

[Kelso]

Found something important not covered in any of the tickets I've seen on this:

1. CONFIG_NFCT_PINS_AS_GPIOS=y is required

2. Power cycling the board (as opposed to simply resetting it after a firmware update) was necessary to change the NFC pin state.

It's not clear to me if there's a different route to making the NFC peripheral transition modes without requiring a power cycle, but this was sufficient to correct the issue.

To Nico7's question, SYS_INIT is a macro from include/zephyr/init.h that allows initialization code to run before main.  It's important to know where it's being used in modules since an error in a SYS_INIT registered function can be hard to debug otherwise.