nRF5340: UICR for device Serial number storage

[Yanpengwu]

Hi Support Team,

I want to design a small Windows tool to flash firmware images and set the device serial number for our device, which is based on nRF5340. Could I ask several questions:

1. For the device serial number, is the best way to store it to UICR(User information configuration registers) of nRF5340, should I use the address OTP[n] 0x100 for this purpose? The expected behavior is the SN can be write by my windows tool, and be read-only in firmware.

2. For the image flash and SN writing, is the best way based on the tool nrfjprog from Nordic, is it feasible?

3. Is there a register in nRF5340 that can prevent firmware reading through the tag? For protection purposes, the firmware image can be erased and written but can not be read by a third party.

Thank you very much.

Best regards,
Yanpeng Wu

[Hung Bui]

Hi Yanpeng, 
1. Yes correct.
2. You can take a look at this ticket: Reading from the UICR / OTP registers on the nRF5340 during runtime 

3. You can lock the chip so that it can't be accessed by the debugger. Please take a look here: https://docs.nordicsemi.com/bundle/ps_nrf5340/page/debugandtrace.html#ariaid-title9

And here: https://docs.nordicsemi.com/bundle/ncs-2.9.0/page/nrf/security/ap_protect.html