[DEV_CONNECT_ERR] When trying to connect to a STM32H747-DISCO

[Me2]

HI there, 

I own a couple of STM32H747-DISC0 boards for a year. I been using them without issues debugging but when started a new project, I do not know what went wrong that cannot access to any core from any ST tool (CubeIDE or CubeProgrammer).

No matter what kind of access I try (Normal/Hotplug/Under Reset) nor reset mode I use, I always have same message "Error: ST-LINK error (DEV_CONNECT_ERROR). I always access using SWD

After removing the LCD panel, I tried also to shortcut R192 (BOOT0) to perform a external bootloader, with same result.. (BTW ST, maybe this thing should be in a jumper...)

However I am able to perform a FW upgrade of the ST-Link device, which I think means is alive.

I tried also MacOS (usually I use windows).

Does someone have a hint?
Thanks in advance.
JUan

[JP2]

Hi JUan,
I had the same behavior with the STM32H747-DISC0 board after we set the BCM7 flag to “CM7 boot disabled” in the option bytes. (The BCM4 flag was set to “boot enabled”.) Afterwards, no connection could be established with the CubeProgrammer.
The solution was to select the correct access port to establish the connection. In the CubeProgrammer, the port is set to “0” by default. However, if only the Cortex-M4 core is running, the connection can only be established if port 3 is selected.

See also this article https://community.st.com/t5/stm32-mcus-boards-and-hardware/dev-connect-err-when-trying-to-connect-to-a-stm32h747-disco/m-p/680663 

Best regards.

JP