STM32H573 – Detecting whether the device is running in the ST System Bootloader

[MarioM]

Hi,

I am working with an STM32H573 and would like to reliably detect when the device is running in the built-in ST System Bootloader.

Is there any supported mechanism to determine that the MCU has entered the System Bootloader?

For example, is there any status information, register, persistent flag, GPIO behavior, or other mechanism that can be used to distinguish the System Bootloader from the normal user application?

The goal is to provide an external indication when the device is in this state. A status LED would be one possible example, but I am mainly interested in whether there is a general and reliable way to detect the System Bootloader state.

In our setup, Secure Manager is enabled, so entering the System Bootloader may also happen as part of the secure boot / recovery flow.

Is there any recommended approach for this on STM32H573 devices?

Thanks!

[Bob S]

Sure - pick a pin that the bootloader doesn’t use (see AN2606) and the H573 doesn’t config out of reset (see the GPIO register “reset values” in the reference manual).  When the bootloader is running the pin will remain in its reset configuration (usually tri-stated or analog input).  When your code is running you can drive it high or low, or toggle an LED, or do whatever.

[Karl Yamashita]

If you’re using USB you can send a console command “STM32_Programmer_CLI.exe -l usb” and Cube programmer should return something similar to this...

      -------------------------------------------------------------------
                       STM32CubeProgrammer v2.22.0
      -------------------------------------------------------------------

=====  DFU Interface   =====

Total number of available STM32 device in DFU mode: 1

  Device Index           : USB1
  USB Bus Number         : 001
  USB Address Number     : 002
  Product ID             : STM32  BOOTLOADER
  Serial number          : FFFFFFFEFFFF
  Firmware version       : 0x011a
  Device ID              : 0x0448

If using UART, send a 0x7F to device. If you are in DFU mode, the bootloader will return 0x79.