Tried 2 different v3.9 boards (both from Tritium and both work on 6.9). Ran both Arduino 2.1.3 as well as 1.8.13. Running the same test config on 6.9 works fine on Serial Monitor and WebUSB. Everything else works fine (so far that I’ve seen). But on 7.7, there is basically nothing happening on the serial monitor (just blank). WebUSB also does not load.
So far no luck.
It just works for me.
I did notice you have KEEP_SAVEFILES_WHEN_PROGRAMMING in your config file, which could potentially be causing problems. ProffieOS 6.9 would probably ignore the savefiles from ProffieOS 7.x though, since they don’t really look like save files.
I also looked through the differences between 7.7 and the github master, and there isn’t a whole lot, and none of them seem like they should affect the serial monitor.
My theory is that there is a bug somewhere which touches memory out of bounds, maybe in the serial code itself. But of course it could be something completely different.
So when the serial monitor doesn’t work, does anything else work? Does the LED pulse or blink?
Tried it in windows, but I still haven’t found anything that resembles this problem.
I do see problems when mass storage is on, and there is no SD card in the board.
Other than that it seems fine.
In fact, it seems weirdly too fine.
Somehow I can access the SD card from the serial monitor with the dir command AND also browse the content of the sd card from windows, which seems weird. Normally I would think I would have to eject the drive before I can list the contents from inside the serial monitor…
Just to try things out, I tried on my Mac and no dice there. WebUSB won’t load, Serial monitor is blank, and solid LED light. USPS finally found where they shipped my black v3 so I can test it on that though I doubt the results will be different.