Best place to store a factory-programmed HW revision on nRF9160?

[purush123]

I need to store a hardware-revision value on an nRF9160 during manufacturing (using something like nrfjprog), and the non-secure application firmware must be able to read this value at runtime to decide logic.

I’m looking for guidance on which nRF9160 memory area is recommended for this purpose.

Requirements:

• Written once at factory (e.g., HW_REV = 1,2,3…).

• Application (non-secure) must be able to read it.

• Application must not be able to overwrite it accidentally.

Questions:

1. What is the best location on nRF9160 to store a small factory-programmed value—UICR OTP, KMU, internal flash region, or external flash?

2. If UICR OTP is used, what is the proper way for non-secure firmware to read it?

3. What is the recommended tool/command for factory programming (e.g., nrfjprog --memwr, J-Link script, etc.)?

Looking for best practices for storing hardware revision or board identification on nRF9160.

[Michal]

Hello,

I would think that UICR->OTP would be the solution, but I will have to double check that.

There is also the zephyr settings subsystem where you define your own partition for that.

Best regards,

Michal

[purush123]

UICR -> OTP works , I can use "nrfjprog --memwr 0x00FF8300 --val 0x00010007" and once written i am unable to change, thats the behaviour that we need .

But main problem is i am unable to read from my non-secure application code , I get BUS-Fault when i try to read this memory, I need a way to read it from my application code . I am using nrf9160 board with NCS 2.7.0 .

is there any limitation that UICR can be accessed from only secure application ? My application is non-secure and i just need to read UICR.

[Michal]

Accessing UICR is only possible from secure application, but you can make a custom secure service in TF-M to access that.

Please check out this sample for how to do it.

Best regards,

Michal

[Emil Lenngren]

Since version 2.8.0 this feature is already present in the SDK. See https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/libraries/security/tfm/tfm_ioctl_api.html#read_service how to use it. You should upgrade to this version (or the latest version) if you still use the older 2.7.0.