RE: UICR

hmolesworth — Sat, 29 May 2021 20:35:56 GMT

On the off chance you are not aware of this "UICR can only be written nWRITE number of times before an erase must be performed using ERASEUICR or ERASEAL" where nWRITE is 181 times. Each write to any location within UICR counts as one of those 181 times, even if the same data is written to the same location. Failure following too many writes (> 181) is evidenced by some '1' bits being read as '0', never the other way round. The errors are also marginal, depending on VDD and number of total writes.

So .. does anything else write to any part of UICR? Including all those UICR writes in SystemInit() in system_nrf52.c?

For the code presented above, the safe correction would be to at least apply the following conditional test:

// Never write to any part of UICR unless a change is required
if (NRF_UICR->CUSTOMER[1] != signValue)
{
   blah blah
}

Also not good to ignore the returned error code from trying to turn off the softdevice:

// Switch off soft device
 result = BLE_and_SD_DEInit();
 
 if (result == shan't) uh_oh