Writing Board Info in UICR and protecting from erase

[RahulSingh]

I am looking for information regarding usage of UICR in nRF52840. I want to store Board information like board version number etc.. in UICR probably in the customer registers for the lifetime of the board. Hence also want to ensure that these information doesn't get erased if we erase the chip completely either via JLINK from SES or via cmd line nrfProj.

If I am correct Access Port Protection (APPROTECT = 0x00) will ensure that UICR doesn't get erased if tried to erase the chip it via debugger, but still with ERASEALL option from cmd line nrfProj, UICR can get erased and we may have to do sector erase to avoid that.

It still looks to me that storing information in UICR for lifetime might not be safe option as by chance if some tries ERASEALL, then we will loose the information store there in UICR.

Is my thinking correct? what would be the ideal way in nrf52840 to store board information permanently and how UICR can help me in that and what would be the correct way or steps to protect UICR data.

[Vidar Berg]

Hello,

The chip including the UICR will be fully erased after an ERASEALL, unfortunately. There is no mechanism in place to preserve certain sectors of flash. Is the debug port going to be accessible for your users?

If I am correct Access Port Protection (APPROTECT = 0x00) will ensure that UICR doesn't get erased if tried to erase the chip it via debugger, but still with ERASEALL option from cmd line nrfProj, UICR can get erased and we may have to do sector erase to avoid that.

It erases everything to prevent attackers from retreiving any data from the chip.

Best regards,

Vidar