Lately, I’ve been working with USB Serial devices, and I’ve discovered that many serial programs don’t like it when the serial device is disconnected.

So I decided to write my own little monitor program in python. It hooks into pyudev to get the add/remove notifications when usb devices are plugged in or removed (so currently it only works under linux).

Source code can be found here. It requires pyudev version 0.16 or newer.

If you run:

./usb-ser-mon.py -l

it will show you the currently connected devices.

USB Serial Device with vendor 'Teensyduino' serial '21973' found @/dev/ttyACM1
USB Serial Device with vendor 'Prolific_Technology_Inc.' found @/dev/ttyUSB0
USB Serial Device with vendor 'STMicroelectronics' serial '00000000050C' found @/dev/ttyACM0

If you want to connect with the STM device (an STM32FDISCOVERY board in this situation), then you might do:

1247 >./usb-ser-mon.py -n Teensy
USB Serial device with vendor 'Teensyduino' serial '21973' connected @/dev/ttyACM1

>>>

In the previous example the Teensy was already connected. If I unplug and replug the Teensy device then I’d see:

USB Serial device @ /dev/ttyACM1  disconnected.

Waiting for USB Serial Device with vendor 'Teensy' ...
USB Serial device with vendor 'Teensyduino' serial '21973' connected @/dev/ttyACM1
Done executing '/src/main.py'
Micro Python for Teensy 3.1
Type "help()" for more information.
>>>

You only need to use as many characters as are required to uniquely identify a device, so I could use:

./usb-ser-mon.py -n STM

to connect to the Discovery board.