Linux: Hard Coding COM port names using simple dmesg & easy UDEV rule. No more random port numbers.

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Paul Daniels

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Published on June 3, 2024 5:13:49 PM ● Video Link: https://www.youtube.com/watch?v=MYhh8KjWtMw

Duration: 5:07

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If you're like me you have a lot of different devices hooked up to your linux machine that utilise USB-Serial port bridge chips for communications. The problem is that many of them do not have unique serial codes and it's not always practical to inspect the data stream when trying to ascertain which one is the device you need to talk to.

Popular serial bridge chips like the CH340, PL230x and CP210x frequently don't have any unique information available to differentiate devices so the way around it is to assign your own COM port names so long as you keep the devices plugged in to the same physical port.

From dmesg output;
usb 1-9.1: New USB device found, idVendor=1a86, idProduct=7523, bcdDevice= 2.64

... you have all the information you need to build your udev rule ...

SUBSYSTEM=="tty", SUBSYSTEMS=="usb", KERNELS=="1-9.1", ATTRS{idVendor}=="1a86", ATTRS{idProduct}=="7523", SYMLINK+="yourUniqueDevName"