Example code to write to UICR

[rmarques]

I am trying to store data to the UICR using SDK16, mesh SDK 4.2.0 and the nRF52840 chip.

I want to write to the UICR once on runtime and never again. To avoid messing with the softdevice, I am trying to write to the UICR before calling ble_stack_init() and after __LOG_INIT to get logs working.

This is the code:

NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen;
while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}

uint32_t * consumer0 = (uint32_t *) 0x10001080;
*consumer0 = 0x00000005;

NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren;
while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
__LOG(LOG_SRC_APP, LOG_LEVEL_INFO, "%d\n", *consumer0);

NVIC_SystemReset();

So we put the NVMC in Write enable, wait for it to be ready, write to consumer0, put it in Read enable, wait for it to be ready and reset the device. I can see 5 logged to Segger console.

Then I comment what I don't need:

//NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen;
//while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}

uint32_t * consumer0 = (uint32_t *) 0x10001080;
//*consumer0 = 0x00000005;

//NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren;
//while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
__LOG(LOG_SRC_APP, LOG_LEVEL_INFO, "%d\n", *consumer0);

//NVIC_SystemReset();

And I see -1 logged to Segger console, meaning the flash still has the 0xFFFF on that position. I can confirm it on Segger Memory explorer that 10001080 is never filled with the data I wanted. Am I doing something wrong?

[dgerman]

Beware that sometimes Flash memory is cached by Segger and does not exactly show what you expect. I refer explicitly to 

exec SetAllowFlashCache =0   

Have you tried exiting Segger and starting it again to see if flash isn really set?

In addition add a check in your coded to see what the value is.

Finally choose your values wisely since if there PREVIOUS value of customer[0] was FFFFFFFF this will work BUT if the previous value was 05000000 it will not since write to flash can only reset bits. It is necessary to erase flash to set it to FFFFFFF

[rmarques]

I tried exiting Segger and rechecking the memory, all was the same. I also added a small check for looking for the change in the flash like so:

//NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen;
//while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}

uint32_t * consumer0 = (uint32_t *) 0x10001080;
//*consumer0 = 0x00000005;
if(*consumer0 == 5){
    __LOG(LOG_SRC_APP, LOG_LEVEL_INFO, "*consumer0 = 5\n");
}
else {
    __LOG(LOG_SRC_APP, LOG_LEVEL_INFO, "Flash not correct, *consumer0 = %d\n", *consumer0);
}

//NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren;
//while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}

//NVIC_SystemReset();

As soon as I comment the lines commented in the code I get the second __LOG: Flash not correct, *consumer0 = -1

[Learner]

Good Morning Thorsrud,

Thank you for the tips.

I must admit I get confused with all these different tools versions.

I know I am using,

Zephyr  OS build v2.6.99-ncs1

nRF Connect SDK v1.7.0

But I am not sure which MDK version I am using. How do I find out?

Einar Thorsrud said:

See IN-142 for more details

This document refers to nRF52832 but I am using nrf52833.