#include "stm32f0xx_hal.h"

// Unset bootloader option bytes 
void bootloader_unset(void)
{
    FLASH_OBProgramInitTypeDef OBParam;
 
    HAL_FLASHEx_OBGetConfig(&OBParam);
 
    if(OBParam.USERConfig != 0xFF)
    {
 
        OBParam.OptionType = OPTIONBYTE_USER;
        OBParam.USERConfig = 0xFF;
 
        HAL_FLASH_Unlock();
        HAL_FLASH_OB_Unlock();
        HAL_FLASHEx_OBErase();
        HAL_FLASHEx_OBProgram(&OBParam);
        HAL_FLASH_OB_Lock();
        HAL_FLASH_OB_Launch();
    }
}


// See thread: https://my.st.com/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/Flat.aspx?RootFolder=https%3a%2f%2fmy.st.com%2fpublic%2fSTe2ecommunities%2fmcu%2fLists%2fcortex_mx_stm32%2fJump%20to%20USB%20DFU%20Bootloader%20in%20startup%20code%20on%20STM32F042&FolderCTID=0x01200200770978C69A1141439FE559EB459D7580009C4E14902C3CDE46A77F0FFD06506F5B&currentviews=185
// Set option bytes to enter bootloader upon reset
void bootloader_enter(void) {

    FLASH_OBProgramInitTypeDef OBParam;
   
    HAL_FLASHEx_OBGetConfig(&OBParam);
  
    OBParam.OptionType = OPTIONBYTE_USER;
    /*Reset NBOOT0 and BOOT_SEL,  see: RM 2.5 Boot configuration*/
    OBParam.USERConfig = 0x77; //Sorry for magic number :)
  
    HAL_FLASH_Unlock();
    HAL_FLASH_OB_Unlock();
  
    HAL_FLASHEx_OBErase();
  
    HAL_FLASHEx_OBProgram(&OBParam);
  
    HAL_FLASH_OB_Lock();
    HAL_FLASH_Lock();
  
    HAL_FLASH_OB_Launch();
}