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example stm32 bootloader for uvision 4?

David Merrill

Hello,

I am looking for a how-to / walk-through for writing a custom bootloader for STM32. I need my device to bootload from attached SPI flash, so I can't use the built-in bootloader. So far I have been unable to find information about how to do this -- can anyone send a pointer to a how-to? (I am using uVision 4).

Thanks,
-David Merrill

Parents
  • 0 in reply to Andy Neil

    Thanks Andy.

    So, just to make sure I understand: I think the way that the example in AN2557 works is the following:

    - IAP driver program gets loaded into the Flash memory at the base address of the Flash (0x0800 0000)

    - User program gets loaded into the flash memory immediately after the IAP driver (0x0800 2000)

    - when the STM32 starts, the IAP driver code checks the state of a button that may or may not be pressed

    - if the button was pressed at startup, it runs the IAP driver, otherwise it jumps to 0x0800 2000 to execute the user program.

    Is that correct? And if so, what do I need to do at compile/link/upload time to put the code in the right places?

    After looking through the project, I have a couple questions: is there a difference between unlocking the flash and disabling write protection?

    (from stm32f10x_flash.c)

    void FLASH_Unlock(void)
{
  /* Authorize the FPEC Access */
  FLASH->KEYR = FLASH_KEY1;
  FLASH->KEYR = FLASH_KEY2;
}

    Then in common.c, there is a call to:

    FLASH_UserOptionByteConfig

    It seems like FLASH_Unlock is always done when the IAP driver starts, and the function that calls FLASH_UserOptionByteConfig can be invoked interactively from the command line.

    Also, it seems that this strategy for bootloading does not make use of the BOOT0 / BOOT1 pins at all -- the system is ALWAYS booting into the Flash (never to the System memory / built-in bootloader) -- is that correct?

    thanks,
    -David

Reply
  • 0 in reply to Andy Neil

    Thanks Andy.

    So, just to make sure I understand: I think the way that the example in AN2557 works is the following:

    - IAP driver program gets loaded into the Flash memory at the base address of the Flash (0x0800 0000)

    - User program gets loaded into the flash memory immediately after the IAP driver (0x0800 2000)

    - when the STM32 starts, the IAP driver code checks the state of a button that may or may not be pressed

    - if the button was pressed at startup, it runs the IAP driver, otherwise it jumps to 0x0800 2000 to execute the user program.

    Is that correct? And if so, what do I need to do at compile/link/upload time to put the code in the right places?

    After looking through the project, I have a couple questions: is there a difference between unlocking the flash and disabling write protection?

    (from stm32f10x_flash.c)

    void FLASH_Unlock(void)
{
  /* Authorize the FPEC Access */
  FLASH->KEYR = FLASH_KEY1;
  FLASH->KEYR = FLASH_KEY2;
}

    Then in common.c, there is a call to:

    FLASH_UserOptionByteConfig

    It seems like FLASH_Unlock is always done when the IAP driver starts, and the function that calls FLASH_UserOptionByteConfig can be invoked interactively from the command line.

    Also, it seems that this strategy for bootloading does not make use of the BOOT0 / BOOT1 pins at all -- the system is ALWAYS booting into the Flash (never to the System memory / built-in bootloader) -- is that correct?

    thanks,
    -David

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