Core refusing to connect to serial or USB [Solved]

I’ve got a :spark: Core which is misbehaving… I can’t get it to do anything with the USB serial.

I’ve plugged it into various machines, used different cables, tried Windows and Linux - and it just won’t show up (either a a COM in Device Manager in Windows, or as /dev/ttyACM0 or /dev/ttyUSB0 or in dmesg in Linux).

It successfully draws power from the USB through.

Any ideas?

I’ve tried clearing memory and factory reset. It connects to the WiFi fine, and I can reflash it from the Web IDE. I first noticed the issue when I wanted to use Serial.begin() in a app - but now I’ve realised it might be a wider issue.

Assuming your hardware is working, the USB serial port is non-existent until Serial.begin(9600) is called (or whatever baud rate you want)… I assume you are calling that from setup()?

1 Like

The best way would be to put the core in DFU mode (aka blinking yellow)

It should then show up in the Serial list.

Otherwise, like what @Raldus mentioned, you need to initialize/open a Serial port using Serial.begin in Setup()

I think the stock Tinker firmware will show up as a serial device when in ‘listening mode’ (blinking blue).

For Windows you’ll need a driver:

For Linux it depends on your system, could be a /dev/ttyACM*, could be a /dev/cuaU*, or a /dev/usbmodem*, etc.


It wasn’t stated, but I’m guessing you have other Core’s that do connect via USB?

It was a problem with the Core itself. After several hard factory resets it finally came back to life!


Would have been nice to know the exact problem…

One reset should be the same as multiple resets. If it’s taking more than one, you might have a hardware problem.