STM32H747I-DISCO bricked after unchecking ECM7 bit on STM32CubeProgrammer

[VHEMaster]

Good day everyone.

I'm trying to build application for dual-core MCU STM32H747XI on Disco board:

• Cortex-M4 core initializes System clock, QSPI and SDRAM and boots M7 core
• Cortex-M7 does all of dirty job like executing instructions from QSPI and etc.

I tried to disable M7 core bootup after reset by uhckecking BCM7 bit on STM32CubeProgrammer.

First time it just throwed me verification error and bit got back to checked. Second time it unchecked successfuly, everything has been applied but the MCU immediately died so DISCO board become bricked.

Now it does not connecting with ST-LINK using SWD, JTAG, different Access Ports, when pressing Reset button and etc. It always says: "Error: No STM32 target found!"

I tried to use System Boot (by shorting R192 on the board, it sets BOOT0 to 1) and connect via UART on STM32CubeProgrammer. It says "Error: Activating device: KO. Please, verify the boot mode configuration and check the serial port configuration. Reset your device then try again."

Also no connection with STM32CubeIDE

Please, help. I'm so dissapointed with this situation.

Best Regards, Maksym Naumchuk

[TDK · Accepted solution]

Download and run STM32 ST-Link Utility.

Connect to the chip using access port 3 in Target -> Settings which connects to the CM4 core.

Re-enable the BOOT_CM7 option byte.

This is supposed to also work in STM32CubeProgrammer but there was a bug last time I tried. May or may not be fixed in the current release.

[VHEMaster]

Thank you, I unbricked it!

But it's kinda tricky way to do it and it worked on second time only. It needed to power the board and connect with ST-LINK Utillity with reset button pressed. If I unpress Reset immediately after pressing Connect it was failing. Needed to wait at least 5 seconds.

Hope it will be helpful for Community. Thank you again!