CODEWITHSUNDEEP
embeddedstm32
LunarEclipse
LunarEclipse

Reputation: 1011

Why would ch341-uart be disconnected from ttyUSB?

I want to flash my STM32 board with my USB serial port. And my STM32 board comes with an extended board which carries CH340.

When I connected the board to my computer, I can see the device with the command lsusb, and the output is Bus 001 Device 039: ID 1a86:7523 QinHeng Electronics CH340 serial converter.

But I can't find the ttyUSB file under /dev path.

I ran dmesg | grep tty, and here is the output:

[1182096.667353] usb 1-9: ch341-uart converter now attached to ttyUSB0
[1182096.729868] audit: type=1130 audit(1637925474.011:3648): pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=brltty-device@sys-devices-pci0000:00-0000:00:14.0-usb1-1\x2d9 comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
[1182096.800144] audit: type=1130 audit(1637925474.081:3649): pid=1 uid=0 auid=4294967295 ses=4294967295 msg='unit=brltty@-sys-devices-pci0000:00-0000:00:14.0-usb1-1\x2d9 comm="systemd" exe="/usr/lib/systemd/systemd" hostname=? addr=? terminal=? res=success'
[1182096.803145] usb 1-9: usbfs: interface 0 claimed by ch341 while 'brltty' sets config #1
[1182096.803731] ch341-uart ttyUSB0: ch341-uart converter now disconnected from ttyUSB0

What's the problem here?

Upvotes: 48

Views: 29760

Answers (4)

LunarEclipse
LunarEclipse

Reputation: 1011

There is the forum post Can't connect serial port - Error: ch341-uart disconnected from ttyUSB0. It seems for an Arch Linux/Manjaro system (I am not sure if it is suitable for other distribution), you need to remove some udev rules.

sudo mv /usr/lib/udev/rules.d/90-brltty-device.rules /usr/lib/udev/rules.d/90-brltty-device.rules.disabled
sudo mv /usr/lib/udev/rules.d/90-brltty-uinput.rules /usr/lib/udev/rules.d/90-brltty-uinput.rules.disabled
sudo udevadm control --reload-rules

I don't know why, but I did it. And it worked. Now I can find my ttyUSB0 device file.

Upvotes: 13

Sheep_Canario
Sheep_Canario

Reputation: 81

I was able to see the device using lsusb and dmesg/grep tty, but I was not able to upload code from PlatformIO.

sudo apt remove brltty

This fixed my upload issue with ESP8266 (CH341-UART converter) on Ubuntu 20.04 (Focal Fossa).

Upvotes: 6

intlsy
intlsy

Reputation: 1390

For Ubuntu 22.04 (Jammy Jellyfish), the simplest solution is to remove the package brltty via sudo apt remove brltty, since it’s unnecessary unless you're using a braille e-reader. However, I am unsure if it could cause errors later on.

Also for information about brltty, visit their site.

Upvotes: 122

user1671163
user1671163

Reputation: 121

So, there is a braille ereader that uses this same serial converter, and the udev rules configure the chip for that device. You actually don't need to remove the udev rules files completely, you can simply disable/comment out the rule for the single device. It is this one:

# Device: 1A86:7523
# Baum [NLS eReader Zoomax (20 cells)]
ENV{PRODUCT}=="1a86/7523/*", ENV{BRLTTY_BRAILLE_DRIVER}="bm", GOTO="brltty_usb_run"

Comment the line starting with ENV.

Upvotes: 12

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