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

[Einar Thorsrud]

Hi Mohamed,

What you have found is correct (specifying family is optional). Specifically, nrfjprog never does an erase without "being told so", so that is no problem. To just flash your firmware if there was nothing there before, you can simply use "nrfjprog --program <hexfile>". If you want to overwrite an existing application (the pages you are writing to are not all FFFF), then add --sectorerase like this: "nrfjprog --program <hex> --sectorerase". With this, all pages that will be written to are erased first, but non of the others, and then the hex file is written.

[Learner]

Hi Thorsrud,

I see, I thought I needed to explicitly specify the pages I wanted to erase because 'sectorerase expects arguments. so I don't need to specify the pages number after --sectorerase at the end of the command line. 

I tried the command 

nrfjprog -f NRF52 --program merged.hex –-sectorerase

First I got this error,

C:\Sandbox\HomeBeacon_dev_sb\build_nrf52833dk_nrf52833_v133_rel\zephyr>nrfjprog -f NRF52 --program merged.hex --sectorerase
ERROR: The operation attempted is unavailable due to readback protection in
ERROR: your device. Please use --recover to unlock the device.
NOTE: For additional output, try running again with logging enabled (--log).
NOTE: Any generated log error messages will be displayed.

Then I tried

C:\Sandbox\HomeBeacon_dev_sb\build_nrf52833dk_nrf52833_v133_rel\zephyr>nrfjprog -f NRF52 --recover --program merged.hex --sectorerase
ERROR: Two arguments were provided that cannot be combined. Use --help to read
ERROR: about the valid argument combinations.
NOTE: For additional output, try running again with logging enabled (--log).
NOTE: Any generated log error messages will be displayed.

Finally, I tried

C:\Sandbox\HomeBeacon_dev_sb\build_nrf52833dk_nrf52833_v133_rel\zephyr>nrfjprog -f NRF52 --recover --program merged.hex
Recovering device. This operation might take 30s.
Parsing image file.
WARNING: A programming operation has been performed without --verify.
WARNING: Programming can fail without error.

But I ended up erasing the content of the UICR which I wanted to avoid.

What am I doing wrong?

Actually, I think the reason the command nrfjprog -f NRF52 --program merged.hex --sectorerase did not work it is because the device had the release version of the code which has CONFIG_DEBUG_PORT_ACCESS=n.

So, I flashed the debug version (CONFIG_DEBUG_PORT_ACCESS=y) into the device then I tried the same command nrfjprog -f NRF52 --program merged.hex --sectorerase again and this time the UICR register was not erased. So, we can flash the device without erasing the whole flash including the UICR only if  CONFIG_DEBUG_PORT_ACCESS=y.

Kind regards

Mohamed

[Einar Thorsrud]

Hi Mohamed,

This is a special case. Reading the output from nrfjprog you see that readback protection is enabled (APPROTECT). And the only way to disable it is to perform a full chip erase (nrfjprog --recover). Clearly you want to avoid this issue in the future, as you want to be able to program/debug several times after the initial programming:

• If you are using older revisions, simply do not enable APPROTECT. As long as it is never enabled, you will not have this problem.
• If you are using the newest revision ICs, you need to recover first with for instance nrfjprog: nrfjprog --recover. This will disable APPROTECT in the UICR and add a small code snippet that unlocks the debug port so that it can be used in the future. However, when you flash your firmware this temporary firmware is deleted, and you must ensure that your firmware does this. For that you must use a MDK version >= 8.40.2, which for instance is included in nRF5 SDK 17.1.0. See IN-142 for more details.

[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.