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I recently performed a system upgrade from Pop OS 21.10 to 22.04 (now on kernel 5.17.5-76051705-generic), after which I began to have issues with connecting my ESP32 via USB to my computer.

Before, the ESP32 would connect and mount to /dev/ttyUSB0. Now, when I plug in the device (in any USB port) no new devices appear in /dev.

This is the dmesg output:

[ 4278.965966] usb 1-3: new full-speed USB device number 3 using xhci_hcd
[ 4279.295021] usb 1-3: New USB device found, idVendor=10c4, idProduct=ea60, bcdDevice= 1.00
[ 4279.295024] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 4279.295026] usb 1-3: Product: CP2102N USB to UART Bridge Controller
[ 4279.295027] usb 1-3: Manufacturer: Silicon Labs
[ 4279.295028] usb 1-3: SerialNumber: <serial number here>
[ 4279.307055] cp210x 1-3:1.0: cp210x converter detected
[ 4279.326127] usb 1-3: cp210x converter now attached to ttyUSB0
[ 4283.346019] usb 1-3: usbfs: interface 0 claimed by cp210x while 'brltty' sets config #1
[ 4283.349113] cp210x ttyUSB0: cp210x converter now disconnected from ttyUSB0
[ 4283.349161] cp210x 1-3:1.0: device disconnected

This is the syslog output:

Jun 11 18:24:19 pop-os kernel: [ 4770.417957] usb 3-3.4: new full-speed USB device number 12 using xhci_hcd
Jun 11 18:24:19 pop-os kernel: [ 4770.644632] usb 3-3.4: New USB device found, idVendor=10c4, idProduct=ea60, bcdDevice= 1.00
Jun 11 18:24:19 pop-os kernel: [ 4770.644636] usb 3-3.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
Jun 11 18:24:19 pop-os kernel: [ 4770.644638] usb 3-3.4: Product: CP2102N USB to UART Bridge Controller
Jun 11 18:24:19 pop-os kernel: [ 4770.644639] usb 3-3.4: Manufacturer: Silicon Labs
Jun 11 18:24:19 pop-os kernel: [ 4770.644640] usb 3-3.4: SerialNumber: <serial number here>
Jun 11 18:24:19 pop-os kernel: [ 4770.646656] cp210x 3-3.4:1.0: cp210x converter detected
Jun 11 18:24:19 pop-os kernel: [ 4770.656718] usb 3-3.4: cp210x converter now attached to ttyUSB0
Jun 11 18:24:19 pop-os mtp-probe: checking bus 3, device 12: "/sys/devices/pci0000:00/0000:00:08.1/0000:0e:00.3/usb3/3-3/3-3.4"
Jun 11 18:24:19 pop-os mtp-probe: bus: 3, device: 12 was not an MTP device

As you can see, the device is initially attached to /dev/ttyUSB0, and then quickly disconnects. In fact, it remains mounted for a moment (a second maybe), so running ls /dev/ttyUSB* produces the correct output if run immediately after the device is plugged in. A second later and nothing is found.

Each time I plug the device in I get the same dmesg output, including the part about brltty, which confused me. I don't understand how that is related.

I am certain this is a software issue since the issue did not occur on the earlier operating system version, and does not occur on a different machine running kernel 5.16. The issue has persisted after a reboot, etc.

Please let me know if I should provide any more logs. I hope I have given enough detail to understand the issue.

1 Answer 1

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The issue turned out to be with brltty. As I do not use a braille display, I simply disabled the brltty systemd service with sudo systemctl mask brltty.path as explained here. I found a similar problem which was solved the same way here.

After this, the device mounts as expected.

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