FezFlea - loosing debugger

Did I find the issue? Yes, I had to Erase All in TinyClr Config tool

I meant where did you find the MOD pin on pad T3?

Oh no. I didn’t find that pin. I tried the only two things on the board that might be it, but the Flea didn’t show up when I plugged it in. I managed to change the debug port using the Config tool.

Hi, sorry for missing this post.

I guess here is what you need, the yellow one is TP3

1 Like

So that pin connects to GND to enable Serial debug on port 1?

Yes, it should be low to switch to UART mode

Just for reference, what is the other one below the LDR switch for? I assume this is NRST as per the schematic?

yes, that is reset line

Having the very same problem with a PICO and a Feather.
I’ve found that the TinyCLR Extension and USB driver gets confused after a while.

Rebooting the PC makes it start working again … for a while. And then I need to reboot again.
Or … uninstall the Flea’s USB Device (SC13048) and let it reinstall.

Problem seems to be with the TinyCLR Visual Studio Extension and SitCore USB Driver.
It THINKS a previous deployment was successful, but it wasn’t. So, when the debugger starts, it errors out because its missing some assemblies. Erasing the Flea/PICO/Feather restarts the deployment, and then it may work (or may not !).

– Don

it could be the extension, also could be your code.

When we develop a project, we usually add a loop in main, waitng for press a button before doing anything next.

void DoRun() {
// project start here

void Main() {

while ( button.Pressed() == false)

// start project


button.Press : you can replace by gpio.Read…

Dat Tran,
My code NEVER gets a chance to execute. The Visual Studio Extension NEVER loads my code.

See the logs at Any plan of improving Visual Studio Extension? - TinyCLR OS - GHI Electronics’ Forums