sudo chmod 666 /dev/ttyUSB0 # Or add your user to the dialout group: sudo usermod -a -G dialout $USER # Log out and back in. Cause: Conflicts with older USB-serial adapters.

lsmod | grep cp210x # or lsmod | grep ftdi_sio

dmesg | tail -20 # Look for: "cp210x converter now attached to ttyUSB0" Your console will appear as /dev/ttyUSB0 or /dev/ttyACM0 .

sudo modprobe cp210x # or sudo modprobe ftdi_sio

A: Microsoft removed many legacy COM port drivers from Windows Update. You must download from Silicon Labs manually.