uicr config issue

[OskarM]

Hi,

i have been struggling with UICR Config in nrf52. The code:

NRF_NVMC->CONFIG = (NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos);
while (NRF_NVMC->READY == NVMC_READY_READY_Busy);

seems to crash program execution. The chip is not freezing, but somehow stops correct execution in a random place. Sometimes in just puts some flash content through the RTT. Looks like a "oops" error or something similar. I had to "walk around" with check before write:

if(!(NRF_NVMC->CONFIG&(NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos)))
	{
		NRF_NVMC->CONFIG = (NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos);
	}
while (NRF_NVMC->READY == NVMC_READY_READY_Busy);

did I messed up something in here?

I want to be always sure to have "Ren" when read, "Wen" when written etc. and this check should be unnecessary.

thanks

[OskarM]

Actually I noticed, that write enable also does the same thing:

NRF_NVMC->CONFIG = (NVMC_CONFIG_WEN_Wen << NVMC_CONFIG_WEN_Pos);

Any clues?

[Susheel Nuguru]

If you are using softdevice, then NVMC is protected module. Accessing it will cause hardfault. You have to use sd_flash_xxx() API in nrf_soc.h If you are not using softdevice, then you have explain more about the fault exception generated.

[OskarM]

Yes, I am using softdevice. I recently moved from SD1.0.3 to the newest and most probably something changed in this area, because this worked previously. Could you point me to some snippet on how to work with UICRs using this API? I am intereseted especially in erasing the UICR. Where is the sd_flash_write "response" received?

[Susheel Nuguru]

you cannot erase UICR without erasing the whole chip. To erase any other page in the flash look into sd_flash_page_erase API. This is asynchronous function, so the function will return immediately. You will get 'NRF_EVT_FLASH_OPERATION_SUCCESS' system event when the flash page erase has completed or you will get NRF_EVT_FLASH_OPERATION_ERROR when the erase failed.

[Susheel Nuguru]

I also forgot to mention that you cannot use this API to write to UICR, since UICR has different address space, softdevice does not allow it at the moment. This feature might be allowed in future releases. So for now if you want to write to UICR, then you have to disable softdevice and then proceed the way you were doing, by directly accessing NVMC registers.