FIrmware faulty jumps into DFU mode while plugging into my PC.

[Param sivan]

STM32L422kb

Hi,

I have created a USB sensor project through MX cube as FreeRtos based CDC device in FS mode. The sensor is detected as a com port in the device manager while I connect to the USB port in my PC. But sometimes it won't, It detected as a DFU(STM32 Bootloader) device under the USB section. It means the firmware jumps into the bootloader during powerup.

How to lock up the bootloader jumps? Is there anything I am missing in the configuration?

Boot0 pin is idle. (No external pull-up or Pulldown).

Thanks,

Param.

[Mike_ST]

>> Boot0 pin is idle. (No external pull-up or Pulldown).

Please configure nSWBOOT0 and nBOOT0/nBOOT1 option bytes with the STM32CubeProgrammer, these options should be available on L422.

[Param sivan]

Thanks for the replay.

Currently, all checkboxes are activated.

Shall I uncheck "nSWBoot0" to directly jump to the main flash memeory?

How to add these settings to the firmware?

[Mike_ST]

>> Shall I uncheck "nSWBoot0" to directly jump to the main flash memory?

As you don't have external Pull-Down on BOOT0, you have to use the option byte. So I recommend to uncheck it.

>> How to add these settings to the firmware?

You can either use the -ob option when programming your boards at production time:

STM32_Programmer_CLI.exe -c port=SWD -d "your firmware" -ob nSWBOOT0=0 nBOOT0=1

Or you can program it from the firmware itself using the FLASH HAL functions, and jump to your code after flashing.

[Param sivan]

Thanks to @Mike_ST​ . It solved my issue :)

I am using the HAL flash function and fixed the bug.

void Write_OptionByte(void)
{
	// Reset nSWBoot0 = 0;
 
	OBInit.USERType = OB_USER_nSWBOOT0;
	OBInit.USERConfig = 0;
	OBInit.OptionType = OPTIONBYTE_USER; // of type FLASHEx_OB_Type
 
	/* Unlock the Flash to enable the flash control register access *************/
	if(HAL_FLASH_Unlock() == HAL_OK)
	{
		if(HAL_FLASH_OB_Unlock()== HAL_OK)
		{
			//if(HAL_FLASHEx_OBErase() == HAL_OK) {
				// program selected option byte
				HAL_FLASHEx_OBProgram(&OBInit); // result not checked as there is no recourse at this point
 
				if(HAL_FLASH_OB_Lock() == HAL_OK) {
					HAL_FLASH_Lock(); // again, no recourse					
				}
			//}
 
		}
	}
}