COM port constantly timing out on newly flashed H743

I’ve just flashed a new Matek H743 with Ardupilot (the latest stable with bl) using the STM32Cube tool yet am unable to connect to the board in Mission Planner. I am getting the correct tones and the LED sequence is correct so the firmware flash was successful; I’ve confirmed that this is the case by attempting to update using Mission Planner which results in the ‘no need, already has latest’ message. Upon connection, the COM port appears (COM9), however when I select it and try and connect the request times out noting that the COM port could not be found.
I have done a full chip erase and re-flashed the board, something I have done many times before (successfully) but I get the same problem.
Appreciate any suggestions.

How is it shown? Something like this?
Com port

No, I only see one option - no slcan

New boards usually have iNav/BF installed on them for initial testing so I flash the ‘2MByte_allzero.bin’ file from Matek first to completely wipe the board, then do a full chip erase from within the STM32CubeProgrammer, then write the bin file for the particular board that includes the bootloader. I haven’t had a problem since I started doing it this way. After that, I can just use MP to load new firmware. If you ever reinstall iNav/BF on the board, then you need to go through the above to cleanly change back to Ardu.


Thanks Kevin; the issue was solved - it turned out the be a driver conflict with my laptop (Windows 11). Hadn’t considered this a possibility as I could detect the COM port/flash without incident.

Hi Paul. Glad you found the solution. Thanks for sharing.