After adding the Thread Debug Library and header code (as instructed here) to the sketch, it fails to flash to the Portenta Device:

Uploading 'Visual_Micro_test_1' to 'Arduino Portenta H7 (M7 core)' using 'COM29'
dfu-util 0.10-dev
Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
Copyright 2010-2021 Tormod Volden and Stefan Schmidt
This program is Free Software and has absolutely no warranty
Please report bugs to http://sourceforge.net/p/dfu-util/tickets/
dfu-util 0.10-dev
Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
Copyright 2010-2021 Tormod Volden and Stefan Schmidt
This program is Free Software and has absolutely no warranty
Please report bugs to http://sourceforge.net/p/dfu-util/tickets/

The uploader returned an error
Warning: Invalid DFU suffix signature
A valid DFU suffix will be required in a future dfu-util release
No DFU capable USB device available 

I did try pressing reset and that did not help, although, when to press reset during the build/load/debug cycle is unclear.

Attached is the log requested.

You should click the reset before upload. The problem is that the board is confused with its usb. 

The board uses a type of upload first introduced for the Arduino Leonardo. When upload attempts to start it has to open the port you have selected and write to it at a speed of 1200 baud. That sends a signal the board looks out for, if it sees the 1200baud connection it re-boots onto a different serial port that must be used for upload.

In your output you can see visual micro scanning the com ports waiting for the new port to appear. It never does. The new port should appear immediately, after 20 secs Visual Micro gives up. This shows that the board is not responding and needs reset. 

Clicking reset during the "scan for new ports" phase will not help and will confuse things further, it must be reset before 
upload is attempted.

This is the trace that shows the scan for new port:-

Quote:

When you hit the issue please try same in the arduino ide. See if the board has an issue as ofte?

Thanks

I changed to a second Portenta H7 and the test sketch uploaded, I added a simple serial print, that sketch uploaded and ran.

So, I switched back to VM and attempted to upload the same sketch to the same Portenta H7 and the upload failed.

Then, back to the classic Arduino IDE and it uploaded fine.

Seems there are two issues, one, my original Portenta H7 has failed in someway, and two, VM is unable to flash the second Portenta.

Checking the upload on my system today:
If double tap the reset button on the board, the Green LED fades in and out to show its in bootloader mode.
Then check the COM Port in IDE of choice is correct.
Then Upload

After stopping a debugging session:
If you cannot upload, repeat the process above.
Also note you have to tap reset once to allow it to re-attach again, again check the COM port before re-attaching.

We are improving the GDB Debugging configuration in the next release which should resolve the error on trying to attach the debugger,  and give an option to reset the board when stop debugging is pressed automatically.  This will be available over the coming day or so, and we will update this thread when it is available.

You can prevent the COM Port scanning in the interim, by adding a local board.txt to the project (vMicro > Add Code > Add Local Board.txt), and paste in the entry below:

upload.use_1200bps_touch=false 

Thank you, some progress

I am able to download the sketch by double-clicking the reset button and placing the Portenta into DFU mode. However, the debugger only ran the very first time I tried the code. It stopped at a breakpoint in Setup and I was able to step-in and over. However, that was only the first time I ran the debugger. Now I see the same message box I saw previously about "unexpected output from gdb."

I am still not able to debug the Portenta H7 with Visual Micro.

I have added the line you suggested to "Board.txt".

This is my procedure:

• Start Visual Studio and open the test solution
• Request Visual Micro to Start Debugging
• Double press the reset switch on the Portenta to enter bootloader mode
• Code compiles and is downloaded
• Visual Micro shows message box "Unable to start debugging ... Unexpected output etc.

Hoping this can be addressed 

More observations:

If I use "Debug/Attach to Process", debugging works every time. I have the serial port drop-down next to the board-selector drop-down set to the DFU port, and the debug port (next to "MIR (Built-In)") set to the normal serial port.

When using the "Start Debugging" selection, and using my procedure from above, I see the error from Visual Micro BEFORE Windows has finished re-enumerating the Portenta after it is being switched back to the normal serial port. This is why GDB cannot start I think.

Quick note: I was able to switch over to debugging my "real" project, a multi-threaded Wi-Fi project, and begin debugging on the M7. Later I need to try out debugging the same code on the M4. Is there anything I should be aware of when debugging the M4?

Also, I have a JLink-Ultra and would really like to be doing this debugging using it. So, would be happy to work with you when you get that feature ready.

Many thanks, I will be purchasing a commercial license right away!