Hi
I develop my own bootloader for STM32L152VC. The bootloader works, but I found something wierd.
When the device is turned on and there is no need to write the flash the program jumps to the application and everythings works properly.
When I write the flash and the program jumps to the application the entire EEPROM is erased. As I noticed it clearly depends on the HAL_FLASH_Unock() and HAL_FLASH_Lock() functions. Unlock clears two bits of the FLASH_PECR register, PELOCK and PRGLOCK. The lock function only sets the PRGLOCK. In the reference manual I found this: "To lock the FLASH_PECR and the data EEPROM again, the software only needs to set the PELOCK bit in FLASH_PECR" If I manually set the PELOCK, the EEPROM content will be preserved. Without setting PELOCK the EEPROM content will be cleared during the jump. According the debugger: at the last command of the bootloader the EEPROM is correct, at the first command of the application the EEPROM is blank.
The question is why did I lose the eeprom content? When will it be deleted?
Thanks.
SET_BIT(FLASH->PECR, FLASH_PECR_PELOCK);
const volatile vector_t *vector_p = (vector_t*) APPLICATION_START_ADDR;
__disable_interrupt(); // 1. Disable interrupts
__set_SP( vector_p->stack_addr ); // 2. Configure stack pointer
SCB->VTOR = APPLICATION_START_ADDR; // 3. Configure VTOR
vector_p->func_p(); // 4. Jump to application
