/* Unlock the Option Byte Access. 
This enables write access to the option bytes. It is locked by default on reset.  */
void flash_unlock_option_bytes(void)
/* Unlock the Option Byte Access. 
This enables write access to the option bytes. It is locked by default on reset.  */
void flash_unlock_option_bytes(void)
{
	FLASH_OPTCR |= FLASH_OPTCR_OPTLOCK;
	FLASH_OPTKEYR = FLASH_OPTKEYR_KEY1;
	FLASH_OPTKEYR = FLASH_OPTKEYR_KEY2;
}