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timopteran
Explorer
June 3, 2024
Solved

STM32h7b0 - System memory bootloader AN2606

  • June 3, 2024
  • 2 replies
  • 5811 views

Hi, I'm having issues on our custom board jumping to the system memory bootrom.

Likely i have a software issue but would like to clarify the system memory address for the bootloader. This is usually listed in AN2606 but there is no explicit mention of the STM32h7b0.
https://www.st.com/resource/en/application_note/cd00167594-stm32-microcontroller-system-memory-boot-mode-stmicroelectronics.pdf

I've been assuming that it is the same as the STM32h7b3 as its just a low flash varient, But as I'm facing issues it would be good to confirm.

Tim

    This topic has been closed for replies.
    Best answer by timopteran

    As suspected software issue. But thank you so much @Tesla DeLorean for your input.

    In my case (using Zephyr) startup / reset assembly was touching CONTROL register CONTROL_SPSEL_Msk.

    Adding the following I believe fixed the 'normal' jump code as found in the following thread:
    https://community.st.com/t5/stm32-mcus/how-to-jump-to-system-bootloader-from-application-code-on-stm32/ta-p/49424

    	if( CONTROL_SPSEL_Msk & __get_CONTROL( ) )
	{ /* MSP is not active */
		__set_CONTROL( __get_CONTROL( ) & ~CONTROL_SPSEL_Msk ) ;
		barrier_isync_fence_full();
		barrier_dsync_fence_full();
	}


    Note for those that might come looking for answers - I am using Zephyrs hook to get a very early startup hook

    SYS_INIT(<jump_function>, EARLY, CONFIG_BOARD_INIT_PRIORITY);


    2 replies

    T
    Tesla DeLorean
    Graduate II
    June 3, 2024

    The H7Ax and H7Bx are materially the same IC

    T
    timopteranAuthor
    Explorer
    June 3, 2024

    @Tesla DeLorean 
    Ah yes, I'd assume so. However with the boot loader being a flash tool I guess they might have a different build of the ROM code and would suggest updating the Section 3 Glossary to match the device to its relevant bootloader section a good idea.

    T
    Tesla DeLorean
    Graduate II
    June 3, 2024

    Some of the newer STM32 you can't jump to the ROM, and a reset is different than a power cycle.

    Technically you can jump, but if it's checking for valid images in flash bank(s) it might just come back.

    Best to have a BOOT0 button, or simply implement you own loader with the features/functions you want, and that your board/design facilitate.

    All the die have the same flash, a sub-set is tested to reduce time-on-tester and provide for price stratification. There's a value stored in system flash indicating the amount tested, and also loader version number.

      T
      timopteranAuthor
      Explorer
      June 4, 2024
      @Tesla DeLorean wrote:

      Some of the newer STM32 you can't jump to the ROM, and a reset is different than a power cycle.

      Technically you can jump, but if it's checking for valid images in flash bank(s) it might just come back.

      Any ideas on how to know this for sure? I'm guessing a launch under debugger is should see the program counter come back into the flash region?

      We do have a BOOT0 switch, but we are migrating a existing design. There is a automated manufacturing test stage where we use this the system bootrom to put in a production test firmware and then to put in our custom bootloader. Could be painful to change this so would like to understand before presenting options. 

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