STM32G070KB with RDP set to level 1 with J-Flash kills the device.

[Zed]

Hi!

Can someone explain to me why this code:

// Is FLASH_CR register locked for writing?
if (FLASH->CR & FLASH_CR_LOCK)
{
	// Unlocking FLASH_CR register
	FLASH->KEYR = KEY1;
	FLASH->KEYR = KEY2;
}
 
// Unlocking FLASH option register
if (FLASH->CR & FLASH_CR_OPTLOCK)
{
	FLASH->OPTKEYR = OPTKEY1;
	FLASH->OPTKEYR = OPTKEY2;
}   
 
// Setting RDP level to 1
FLASH->OPTR &= ~FLASH_OPTR_RDP;
FLASH->OPTR |= 0xBB;  // Any value except 0xAA and 0xCC
 
while (FLASH->SR & FLASH_SR_BSY1);
 
FLASH->CR |= FLASH_CR_OPTSTRT;
 
while (FLASH->SR & FLASH_SR_BSY1);
 
// Updating option bytes by resetting of the device
FLASH->CR |= FLASH_CR_OBL_LAUNCH;

kills STM32G070KB device, when was written with J-Flash, but works great with STM32G071CB with the same Errata note for RDP protection.

Same code works great for both MCUs when were written with Segger Embedded Studio.

PS: I'm also posting this question on Segger's forum.

Thank you!

[vamsi]

With RDP Level 1 being enabled, MCU is not booting up completely once out of 5 times. It is getting stuck even before reaching main(). With this kind of behaviour, indeed we can't deliver the product out. So we are being forced to remove the RDP altogether.