RE: Read/write UICR CUSTOMER register under Zephyr

AndyM — Fri, 17 Feb 2023 20:52:15 GMT

Thank you!

Andy

RE: Read/write UICR CUSTOMER register under Zephyr

Sigurd Hellesvik — Fri, 17 Feb 2023 12:23:13 GMT

Update:

I found an API for the NVMC: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrfx/drivers/nvmc/index.html

Regards,
Sigurd Hellesvik

RE: Read/write UICR CUSTOMER register under Zephyr

Sigurd Hellesvik — Fri, 17 Feb 2023 12:11:53 GMT

Hi,

[quote user=""]-Does the Soft Device have to be disabled before NRF_UICR->CUSTOMER area can be written?[/quote]

The UICR is written using the NVMC. In the nRF5 SDK, the Soft Device prevented the application from using the NVMC.
However, I do not think the SoftDevice Controller in the nRF Connect SDK prevents this.

So I think it should work fine.

[quote user=""]What API should be used?[/quote]

The NVMC and UICR are simple enough not to need an API.
See my unofficial sample for an example of how to write to the UICR: https://github.com/hellesvik-nordic/samples_for_nrf_connect_sdk/blob/main/ctrl-ap/eraseprotect/src/main.c#L10-L15.

EDIT: See new comment on API

(This code/configuration is not thoroughly tested or qualified and should be considered provided "as-is". Please test it with your application and let me know if you find any issues.)

[quote user=""]-Is a reboot required?[/quote]

Yes. From Writing to user information configuration registers (UICR):

"User information configuration registers (UICR) are written in the same way as flash. After UICR has been written, the new UICR configuration will take effect after a reset."

[quote user=""]-Should the UICR be erased first ? (some posts say it should) [/quote]

Short answer: Yes

Long answer:

When erased, all flash bits are set to "1". The NVMC can only change 1->0. So if you can change 0b11110000 -> 0b01110000, but not 0b11110000 -> 0b11110001.
From Writing to flash:

"The NVMC is only able to write 0 to bits in the flash that are erased (set to 1). It cannot rewrite a bit back to 1. Only full 32-bit words can be written to flash using the NVMC interface. [...]"

Regards,
Sigurd Hellesvik