Erase UICR and merge Bootloader problem

Question

Hello,

I am using NRF52832 with soft device 13.0.0 and Nordic's bootloader from the examples.

What I do is develop an application which stores some values in uicr registers 0-7 (no soft device enabled yet). Before storing the values I erase the uicr registers at device startup, using the following code. (Then the rest of the application executes)

	 SEGGER_RTT_WriteString(0, "Deleting uicr \r\n");
	 NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Een << NVMC_CONFIG_WEN_Pos;
	 while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
	 NRF_NVMC->ERASEUICR = 1;
	 while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
	 
	SEGGER_RTT_WriteString(0, "Update  Version \r\n");

	NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen << NVMC_CONFIG_WEN_Pos;
	while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
	NRF_UICR->CUSTOMER[0] = hardware_version_reg;  // a uint32 value
	NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos;
    while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}

Everything works fine when I test the application without a bootloader.

In the next step I use the following commands to create a hex file which includes the soft device, the bootloader (DFU) and the application:

nrfutil settings generate --family NRF52 --application testing_firmware_v01.04.hex --application-version 0x0104 --bootloader-version 0x0103 --bl-settings-version 1 bootloader_setting.hex
mergehex --merge feel_bootloader_v1.3.hex bootloader_setting.hex --output Bootldr_Settings.hex
mergehex --merge Bootldr_Settings.hex s132_nrf52_4.0.2_softdevice.hex --output SoftAndBoot.hex
mergehex --merge SoftAndBoot.hex feel_testing_firmware_v01.04.hex --output FW_merged.hex

This last hex file (FW_merged) is what i use to program the device with nRFgo Studio. Up to now, during the development, everything worked fine with this procedure.

When I added the code to erase and write the uicr as mentioned above a strange problem occurred.
When I used the FW_merged file to program the device in nRFgo Studio the bootloader would not be programmed in the device. Only the softdevice and the application would be programmed. The verification also failed. If I program the bootloader separately after that, the verification succeeds and the device works ok.

After some experimentation I saw that the command NRF_NVMC->ERASEUICR = 1; alone would cause that problem. If I comment this line then everything runs smoothly again and the bootloader is programmed properly with the hex file.

Any ideas why this might happen?

Thank you in advance

Hung Bui · Accepted Answer

Hi Dimitris, 
 I would not suggest to use nRFGo Studio for programming. Please use nrfjprog. 
 With nRFGo Studio the chip may not be halted between programming and verification. And if you do any flash modification in between it may result in verification failed. 
 Please try again with nrfjprog and provide us the log/screenshot. 
 Please note that even though there is part of the UICR is "reserved for customer" but when you erase the UICR the whole page is erased.You would need to make sure you back up the rest of UICR page and write it back after you erase.

Hung Bui · Answer

I don't think you can write a whole page by just calling *NRF_UICR = uicr_cpy; You need to write them word by word (32 bit) 
 Could you please check after the erase and write to the UICR; you have the correct start address of the bootloader (NRF_UICR_BOOTLOADER_START_ADDRESS) at : NRF_UICR_BASE + 0x14 
 And the correct address of the MBR Param page address at NRF_UICR_BASE + 0x18

Hung Bui · Answer

Hi Dimitris, 
 When you use the bootloader you must be very careful with the UICR. This is because we store the bootloader address in the UICR. You can read about that here . 
 If you have some data that need to be changed more often, I would suggest to use a dedicated flash page to store, instead of using UICR. UICR is more of something like serial number, or hard coded configuration. And please be aware and avoid the address that is used by the bootloader.

Erase UICR and merge Bootloader problem

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