Writing data to UICR region and flashing device

Question

I'm trying to accomplish two things:

1. Write 2 values to the UICR (2 arrays actually - a serial number and encryption keys).
2. Flash the device in such a way that the information in UICR is preserved.

My questions:

1. Whats the UICR address range? (Based on the NRF SDK, the UICR base address is 0x10001000UL). The reason I ask is because I can see in the fstorage example that you can specify the start and end addresses of the flash region to reserve for your purposes. In my case I would like to reserve memory starting from the UICR address base. What's the recommended address range to use?

2. Using nrfjprog, I can specify which areas of flash to erase and keep UICR, by specifying the start and end address of the regions I want to erase. Would it make sense to simply specify the address range as 00000000 - 000ffffff (this is the entire flash) memory range. If I specify this range, would the programmer wipe everything except UICR data (if i specify the --sectorerase option)? I can see from my current application that it lies in the address range 00000000 - 00012b07.
Any reccommendations on what address range to specify to erase?

For now I'm trying to accomplish this without SoftDevice enabled.

Thanks (I'm a bit new to memory management) :)

Vidar Berg · Accepted Answer

fstorage is not suitable for writing data to the UICR. I'd recommend you to copy the approach used to enable the reset pin in system_nrf52840 if you need the app to set the serial number and encryption keys at runtime. if (((NRF_UICR->PSELRESET[0] & UICR_PSELRESET_CONNECT_Msk) != (UICR_PSELRESET_CONNECT_Connected << UICR_PSELRESET_CONNECT_Pos)) || ((NRF_UICR->PSELRESET[1] & UICR_PSELRESET_CONNECT_Msk) != (UICR_PSELRESET_CONNECT_Connected << UICR_PSELRESET_CONNECT_Pos))){ NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen << NVMC_CONFIG_WEN_Pos; //<-- Enable flash write while (NRF_NVMC->READY == NVMC_READY_READY_Busy){} NRF_UICR->PSELRESET[0] = 21; //<-- write value to UICR register while (NRF_NVMC->READY == NVMC_READY_READY_Busy){} <-- wait until write is complete NRF_UICR->PSELRESET[1] = 21; //<-- write value to UICR register while (NRF_NVMC->READY == NVMC_READY_READY_Busy){} NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos; // <-- disable write access while (NRF_NVMC->READY == NVMC_READY_READY_Busy){} NVIC_SystemReset(); // <-- Pinreset functionality is enabled after reset } Note that it's not possible to erase UICR from the app, so you cannot update an existing value in UICR. Also, it's not possible to write to UICR while the softdevice is enabled.

Writing data to UICR region and flashing device

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