Can I set or act like that the boot0 pin set by the software? I use STM32F427VI. Thanks in advance.

[Tesla DeLorean]

You can call into the ROM, the processor can execute any arbitrary code you point it too.

You can remap memory, get the Reference Manual, search MEMRMP

[PIyak.958]

Thank you for your answer.

I've tried this with this code. But it doesnt work. Do you see any mistakes?

/**

 * Function to perform jump to system memory boot from user application

 *

 * Call function when you want to jump to system memory

 */

void JumpToBootloader(void) {

 void (*SysMemBootJump)(void);

   /**

    * Step: Set system memory address.

    *      

    *      For STM32F429, system memory is on 0x1FFF 0000

    *      For other families, check AN2606 document table 110 with descriptions of memory addresses

    */

   volatile uint32_t addr = 0x1FFF0000;

   /**

    * Step: Disable RCC, set it to default (after reset) settings

    *      Internal clock, no PLL, etc.

    */

   HAL_RCC_DeInit();

   /**

    * Step: Disable systick timer and reset it to default values

    */

   SysTick->CTRL = 0;

   SysTick->LOAD = 0;

   SysTick->VAL = 0;

   /**

    * Step: Disable all interrupts

    */

   __disable_irq();

   /**

    * Step: Remap system memory to address 0x0000 0000 in address space

    *      For each family registers may be different.

    *      Check reference manual for each family.

    *

    *      For STM32F4xx, MEMRMP register in SYSCFG is used (bits[1:0])

    *      For STM32F0xx, CFGR1 register in SYSCFG is used (bits[1:0])

    *      For others, check family reference manual

    */

   //Remap by hand... {

   //SYSCFG->MEMRMP = 0x01;

   //} ...or if you use HAL drivers

   __HAL_SYSCFG_REMAPMEMORY_SYSTEMFLASH();   //Call HAL macro to do this for you

   /**

    * Step: Set jump memory location for system memory

    *      Use address with 4 bytes offset which specifies jump location where program starts

    */

   SysMemBootJump = (void (*)(void)) (*((uint32_t *)(addr + 4)));

   /**

    * Step: Set main stack pointer.

    *      This step must be done last otherwise local variables in this function

    *      don't have proper value since stack pointer is located on different position

    *

    *      Set direct address location which specifies stack pointer in SRAM location

    */

   __set_MSP(*(uint32_t *)addr);

   /**

    * Step: Actually call our function to jump to set location

    *      This will start system memory execution

    */

   SysMemBootJump();

   /**

    * Step: Connect USB<->UART converter to dedicated USART pins and test

    *      and test with bootloader works with STM32 Flash Loader Demonstrator software

    */

}

[Tesla DeLorean]

Is the SYSCFG clock enabled, does someone of the other side enable the CPU IRQ?

Used this method on the F205/F405 for a decade or more

Reset_Handler    PROC
                 EXPORT  Reset_Handler             [WEAK]
        IMPORT  SystemInit
        IMPORT  __main
 
                LDR     R0, =0x2001FFFC
                LDR     R1, =0xBEEFBEEF
                LDR     R2, [R0, #0]
                CMP     R1, R2
                BNE     NotDFuse
                STR     R0, [R0, #0] ; Invalidate
                LDR     R0, =0x40023844 ; RCC_APB2ENR
                LDR     R1, =0x00004000 ; ENABLE SYSCFG CLOCK
                STR     R1, [R0, #0]
                LDR     R0, =0x40013800 ; SYSCFG_MEMRMP
                LDR     R1, =0x00000001 ; MAP ROM AT ZERO
                STR     R1, [R0, #0]
                LDR     R0, =0x1FFF0000 ; ROM BASE
                LDR     SP,[R0, #0]
                LDR     R0,[R0, #4]
                BX      R0
NotDFuse
                LDR     R0, =SystemInit
                BLX     R0
 
                LDR     R0, =__main
                BX      R0
 
                ENDP ; sourcer32@gmail.com

[Tesla DeLorean]

The F427 may be a more complex beast with the ROM checking banking and bootable FLASH code. Use a Debugger, and determine if the ROM just bounces back control to your Reset Handler. In which case you'll probably want to implement your own loader to facilitate USB/DFU or USART update methods.

[PIyak.958]

Hi Clive

I think, I dont understan what exactly is to do. I'm new to MCU.

I read many posts and also this one.

https://community.arm.com/developer/tools-software/tools/f/keil-forum/41955/stm32l072-jumping-to-embedded-bootloader-from-application-code

"Mixing up random ideas you copy and paste is not programming. Read the manuals and understand what you are doing."

I really want to understand how its works and what is to do.

Can yoe please help me?

What I know or think to know:

• write smt. to ROM (0xBEEFBEEF)
• and restart
• is that what you wrote there in ROM then remap system memory to 0

Is that correct or is smth. missing?

Just crarify the thing on a hingher level and the go step by step deeper.

I hope you can help me to go trough the things and finally to reach tje goal.

Thanks in advance.