Ch341 serial driver4/8/2023 Now as long as I attach a specific device to the same USB port on my system, it will have the same device node. You can see the new symlink in the DEVLINKS value, and looking at /dev/usbserial we can see the expected symlinks: # tree /dev/usbserialĪnd there have it. Looking at the available attributes for a serial device, we see: # udevadm info -a -n /dev/ttyUSB0 While that sounds conceptually simple, it took me a while to figure out the correct udev rules. Ouch.Ī common solution to this problem is to create device names based on the USB topology – that is, assign names based on a device’s position in the USB bus: e.g., when attaching a new USB serial device, expose it at something like /dev/usbserial//. On more than one occasion, I have accidentally re-flashed the wrong device. This by itself would be a manageable problem, except that the device names assigned to these devices aren’t constant: depending on the order in which they get plugged in (and the order in which they are detected at boot), a device might be /dev/ttyUSB0 one day and /dev/ttyUSB2 another day. Unfortunately, they have a cheap CH340 serial adapter on board, which means that from the perspective of Linux these devices are all functionally identical – there’s no way to identify one device from another. I like to fiddle with Micropython, particularly on the Wemos D1 Mini, because these are such a neat form factor.
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