stm32h757i-eval can't connect stm32 target after selecting M4 for boot and deselecting M7

[kgardas]

Hello,

I have stm32h757i-eval board here. I've used stm32cubeprogrammer to edit OB where I've unselected M7 core from booting and left just M4 selected. This was done in intention to boot just M4 core and leave M7 core halted.

When I modified OB this way and then apply, after few seconds I got a message that CubeProgrammer is not able to connect to the target. I've tried again stopping and starting CubeProgrammer and it crashed clearly (ubuntu 20.04, cube programmer 2.9.0, known issue). I've found a solution for crash, installed 2.10.0 on ubuntu 20.04) and attempted to connect board again and in the log (no crash) I see "Error: No STM32 target found!".

I've decided to duplicate the issue on Windows 10 + STM32CubeProgremmer 2.10.0 and again I see the same error.

Whole log on Windows looks:

  21:26:28 : STM32CubeProgrammer API v2.10.0 | Windows-64Bits 
  21:26:28 : ST-LINK error (DEV_CONNECT_ERR)
  21:26:40:995 : STLinkUSBDriver.dll loaded
  21:26:40:997 : STLinkUSBDriver.dll loaded
  21:26:40:997 : ST-LINK SN  : 003E00493137511033333639
  21:26:40:997 : ST-LINK FW  : V3J9M3
  21:26:40:997 : Board       : STM32H757I-EVAL
  21:26:40:998 : Voltage     : 3.28V
  21:26:41:400 : No STM32 target found!
  21:26:41:434 : STLinkUSBDriver.dll loaded
  21:26:41:434 : ST-LINK SN  : 003E00493137511033333639
  21:26:41:434 : ST-LINK FW  : V3J9M3
  21:26:41:435 : Board       : STM32H757I-EVAL
  21:26:41:435 : Voltage     : 3.28V
  21:26:41:840 : Error: No STM32 target found!
  21:26:41:909 : Disconnected

I've also tested the way of selecting booting not from flash but from sysboot by switching SW1 to position 1, but this does not help either.

My question hence is: is there any way how to recover the board from this bricked state?

Thanks a lot!

Karel

[Walid ZRELLI]

Hello @kgardas​ 

First, check that the jumpers are correct on your board, especially the one for the ST-LINK.

Then, try to connect your board with ST-LINK Utility or STM32CubeProgrammer.

In the ST-LINK configuration area, try the following configuration:

Serial number: Refresh to get your ST-LINK serial

Mode: Under reset

Reset mode: Core reset

Finally, try to connect your board.

Otherwise, you may have damaged the board.

I hope this helps.

BeST Regards,

Walid

[kgardas · Accepted solution]

Hello Walid,

thanks a lot for your help. Actually and just for the record it has not worked till my colleague advice me to use access port value set to 3 and explained that this is what I need to use to switch JTAG to connect directly to M4 which I needed since my M7 was switched off.

The board is working again till my next configuration incident I guess. :)

Thanks!

Karel

[Walid ZRELLI]

Great news! Thanks for sharing the solution :smiling_face_with_smiling_eyes:.