Can't connect serial port - Error: ch341-uart disconnected from ttyUSB0

Guys, I can’t use serial usb port , ttyUSB0.

I get "ch341-uart converter now disconnected from ttyUSB0"

I do plug the serial usb and instantly i get the error disconnected reported above and in dmesg | grep USB output

I already used the Usb serial console cable on this machine with previously debian system, I’m using manjaro now.

Please help

Here is some info

System:    Kernel: 5.10.70-1-MANJARO x86_64 bits: 64 compiler: gcc v: 11.1.0 Desktop: GNOME 40.5
           tk: GTK 3.24.30 wm: gnome-shell dm: GDM 40.1 Distro: Manjaro Linux base: Arch Linux
Machine:   Type: Laptop System: LENOVO product: 81S9 v: Lenovo IdeaPad S145-15IWL serial: <filter>
           Chassis: type: 10 v: Lenovo IdeaPad S145-15IWL serial: <filter>
           Mobo: LENOVO model: LNVNB161216 v: SDK0J40688 WIN serial: <filter> UEFI: LENOVO v: ASCN37WW
           date: 07/04/2019
Battery:   ID-1: BAT0 charge: 31.2 Wh (98.1%) condition: 31.8/35.0 Wh (90.8%) volts: 8.5 min: 7.5
           model: SMP L16M2PB2 type: Li-poly serial: <filter> status: Unknown cycles: 19
           Device-1: hidpp_battery_0 model: Logitech Wireless Keyboard serial: <filter>
           charge: 55% (should be ignored) rechargeable: yes status: Discharging
           Device-2: hidpp_battery_1 model: Logitech Wireless Mouse serial: <filter>
           charge: 55% (should be ignored) rechargeable: yes status: Discharging
Memory:    RAM: total: 19.43 GiB used: 4.22 GiB (21.7%)
           RAM Report: permissions: Unable to run dmidecode. Root privileges required.
CPU:       Info: Quad Core model: Intel Core i7-8565U bits: 64 type: MT MCP arch: Kaby Lake note: check
           rev: C cache: L2: 8 MiB bogomips: 32012
           Speed: 600 MHz min/max: 400/4600 MHz Core speeds (MHz): 1: 600 2: 600 3: 600 4: 600 5: 600
           6: 600 7: 600 8: 600
           Flags: 3dnowprefetch abm acpi adx aes aperfmperf apic arat arch_capabilities arch_perfmon art
           avx avx2 bmi1 bmi2 bts clflush clflushopt cmov constant_tsc cpuid cpuid_fault cx16 cx8 de
           ds_cpl dtes64 dtherm dts epb ept ept_ad erms est f16c flexpriority flush_l1d fma fpu fsgsbase
           fxsr ht hwp hwp_act_window hwp_epp hwp_notify ibpb ibrs ibrs_enhanced ida intel_pt invpcid
           invpcid_single lahf_lm lm mca mce md_clear mmx monitor movbe mpx msr mtrr nonstop_tsc nopl nx
           pae pat pbe pcid pclmulqdq pdcm pdpe1gb pebs pge pln pni popcnt pse pse36 pts rdrand rdseed
           rdtscp rep_good sdbg sep smap smep ss ssbd sse sse2 sse4_1 sse4_2 ssse3 stibp syscall tm tm2
           tpr_shadow tsc tsc_adjust tsc_deadline_timer vme vmx vnmi vpid x2apic xgetbv1 xsave xsavec
           xsaveopt xsaves xtopology xtpr
Graphics:  Device-1: Intel WhiskeyLake-U GT2 [UHD Graphics 620] vendor: Lenovo driver: i915 v: kernel
           bus-ID: 00:02.0 chip-ID: 8086:3ea0 class-ID: 0300
           Device-2: NVIDIA GM108M [GeForce MX110] vendor: Lenovo driver: nvidia v: 470.63.01
           bus-ID: 01:00.0 chip-ID: 10de:174e class-ID: 0302
           Device-3: Acer Integrated Camera type: USB driver: uvcvideo bus-ID: 1-7:5 chip-ID: 5986:1135
           class-ID: 0e02 serial: <filter>
           Display: x11 server: 1.20.13 compositor: gnome-shell driver: loaded: modesetting,nvidia
           unloaded: nouveau alternate: fbdev,nv,vesa resolution: <missing: xdpyinfo>
           OpenGL: renderer: Mesa Intel UHD Graphics 620 (WHL GT2) v: 4.6 Mesa 21.2.3 direct render: Yes
Audio:     Device-1: Intel Cannon Point-LP High Definition Audio vendor: Lenovo driver: snd_hda_intel
           v: kernel bus-ID: 00:1f.3 chip-ID: 8086:9dc8 class-ID: 0403
           Sound Server-1: ALSA v: k5.10.70-1-MANJARO running: yes
           Sound Server-2: JACK v: 1.9.19 running: no
           Sound Server-3: PulseAudio v: 15.0 running: yes
           Sound Server-4: PipeWire v: 0.3.38 running: no
Network:   Device-1: Intel Dual Band Wireless-AC 3165 Plus Bluetooth driver: iwlwifi v: kernel
           bus-ID: 02:00.0 chip-ID: 8086:3166 class-ID: 0280
           IF: wlp2s0 state: up mac: <filter>
           IP v4: <filter> type: dynamic noprefixroute scope: global broadcast: <filter>
           IP v6: <filter> type: dynamic noprefixroute scope: global
           IP v6: <filter> type: noprefixroute scope: link
           Device-2: TP-Link UE300 10/100/1000 LAN (ethernet mode) [Realtek RTL8153] type: USB
           driver: r8152 bus-ID: 1-4:4 chip-ID: 2357:0601 class-ID: 0000 serial: <filter>
           IF: enp0s20f0u4 state: up speed: 1000 Mbps duplex: full mac: <filter>
           IP v4: <filter> type: dynamic noprefixroute scope: global broadcast: <filter>
           IP v6: <filter> type: dynamic noprefixroute scope: global
           IP v6: <filter> type: noprefixroute scope: link
           WAN IP: <filter>
Bluetooth: Device-1: Intel Bluetooth wireless interface type: USB driver: btusb v: 0.8 bus-ID: 1-10:6
           chip-ID: 8087:0a2a class-ID: e001
           Report: hciconfig ID: hci0 rfk-id: 3 state: up address: <filter> bt-v: 2.1 lmp-v: 4.2
           sub-v: 1000 hci-v: 4.2 rev: 1000
Logical:   Message: No logical block device data found.
RAID:      Message: No RAID data found.
Drives:    Local Storage: total: 1.13 TiB used: 186.91 GiB (16.2%)
           ID-1: /dev/sda vendor: Western Digital model: WD10SPZX-24Z10 size: 931.51 GiB speed: 6.0 Gb/s
           type: HDD rpm: 5400 serial: <filter> rev: 1A05 scheme: GPT
           ID-2: /dev/sdb vendor: Western Digital model: WDS240G2G0B-00EPW0 size: 223.58 GiB
           speed: 6.0 Gb/s type: SSD serial: <filter> rev: 0000 scheme: GPT
           Message: No optical or floppy data found.
Partition: ID-1: / size: 210.83 GiB used: 19.1 GiB (9.1%) fs: ext4 dev: /dev/sdb3 label: N/A
           uuid: 0c5e50f1-2089-4cca-985e-5711dcc6620e
           ID-2: /boot/efi size: 511 MiB used: 3.7 MiB (0.7%) fs: vfat dev: /dev/sdb1 label: N/A
           uuid: A615-C1A3
           ID-3: /home size: 915.89 GiB used: 167.81 GiB (18.3%) fs: ext4 dev: /dev/sda1 label: Home
           uuid: 873438e7-ee36-465a-a2d9-7708f72440b3
Swap:      ID-1: swap-1 type: partition size: 7.81 GiB used: 0 KiB (0.0%) priority: -2 dev: /dev/sdb2
           label: N/A uuid: 3447bb15-d41a-4b4b-a5c2-80382431824e
Unmounted: Message: No unmounted partitions found.
USB:       Hub-1: 1-0:1 info: Full speed (or root) Hub ports: 12 rev: 2.0 speed: 480 Mb/s
           chip-ID: 1d6b:0002 class-ID: 0900
           Device-1: 1-1:9 info: QinHeng CH340 serial converter type: <vendor specific> driver: N/A
           interfaces: 1 rev: 1.1 speed: 12 Mb/s power: 96mA chip-ID: 1a86:7523 class-ID: ff00
           Device-2: 1-3:3 info: Logitech Unifying Receiver type: Keyboard,Mouse
           driver: logitech-djreceiver,usbhid interfaces: 2 rev: 2.0 speed: 12 Mb/s power: 98mA
           chip-ID: 046d:c534 class-ID: 0301
           Device-3: 1-4:4 info: TP-Link UE300 10/100/1000 LAN (ethernet mode) [Realtek RTL8153]
           type: Network driver: r8152 interfaces: 1 rev: 2.1 speed: 480 Mb/s power: 180mA
           chip-ID: 2357:0601 class-ID: 0000 serial: <filter>
           Device-4: 1-7:5 info: Acer Integrated Camera type: Video driver: uvcvideo interfaces: 2
           rev: 2.0 speed: 480 Mb/s power: 500mA chip-ID: 5986:1135 class-ID: 0e02 serial: <filter>
           Device-5: 1-10:6 info: Intel Bluetooth wireless interface type: Bluetooth driver: btusb
           interfaces: 2 rev: 2.0 speed: 12 Mb/s power: 100mA chip-ID: 8087:0a2a class-ID: e001
           Hub-2: 2-0:1 info: Full speed (or root) Hub ports: 6 rev: 3.1 speed: 10 Gb/s
           chip-ID: 1d6b:0003 class-ID: 0900
Sensors:   System Temperatures: cpu: 49.0 C mobo: N/A
           Fan Speeds (RPM): N/A
Info:      Processes: 289 Uptime: 28m wakeups: 8 Init: systemd v: 249 Compilers: gcc: 11.1.0 Packages:
           pacman: 1449 Shell: Zsh v: 5.8 running-in: gnome-terminal inxi: 3.3.07

dmesg | grep USB

[ 1173.086178] usb 1-1: USB disconnect, device number 8
[ 1178.766446] usb 1-1: new full-speed USB device number 9 using xhci_hcd
[ 1178.907422] usb 1-1: New USB device found, idVendor=1a86, idProduct=7523, bcdDevice= 2.54
[ 1178.907431] usb 1-1: New USB device strings: Mfr=0, Product=2, SerialNumber=0
[ 1178.907436] usb 1-1: Product: USB2.0-Ser!
[ 1178.912408] ch341-uart ttyUSB0: break control not supported, using simulated break
[ 1178.912640] usb 1-1: ch341-uart converter now attached to ttyUSB0
[ 1178.999665] ch341-uart ttyUSB0: ch341-uart converter now disconnected from ttyUSB0


Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 005: ID 5986:1135 Acer, Inc Integrated Camera
Bus 001 Device 004: ID 2357:0601 TP-Link UE300 10/100/1000 LAN (ethernet mode) [Realtek RTL8153]
Bus 001 Device 003: ID 046d:c534 Logitech, Inc. Unifying Receiver
Bus 001 Device 006: ID 8087:0a2a Intel Corp. Bluetooth wireless interface
Bus 001 Device 009: ID 1a86:7523 QinHeng Electronics CH340 serial converter
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

I had a similar issue with a CH341. It was being picked up as a braille terminal. Do you get a message similar to
usb 1-1.2: usbfs: interface 0 claimed by skeleton while 'brltty' sets config #1
somewhere in the dmesg log? If so, renaming or moving the udev rules may help.

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

See here for more info:

1 Like

This is it, thanks @iracigt

I do use qemu and it did install brltty package

sudo pacman -Qi brltty                                           ✔ 
Name            : brltty
Version         : 6.4-1
Description     : Braille display driver for Linux/Unix
Architecture    : x86_64
URL             :
Licenses        : LGPL2.1
Groups          : None
Provides        :
Depends On      : bluez-libs  gcc-libs  glibc  liblouis  libspeechd  pcre2
                  polkit  tcl
Optional Deps   : at-spi2-core: X11/GNOME Apps accessibility [installed]
                  atk: ATK bridge for X11/GNOME accessibility [installed]
                  espeak-ng: espeak-ng driver
                  java-runtime: Java support [installed]
                  libxaw: X11 support [installed]
                  libxt: X11 support [installed]
                  libx11: for xbrlapi [installed]
                  libxfixes: for xbrlapi [installed]
                  libxtst: for xbrlapi [installed]
                  ocaml: OCaml support
                  python: Python support [installed]
                  speech-dispatcher: speech-dispatcher driver
Required By     : qemu
Optional For    : None
Conflicts With  : None
Replaces        : None
Installed Size  : 8,35 MiB
Packager        : David Runge <>
Build Date      : sex 24 set 2021 16:57:35
Install Date    : qua 13 out 2021 14:26:05
Install Reason  : Installed as a dependency for another package
Install Script  : Yes
Validated By    : Signature

Thanks again!

1 Like

Fortunately with qemu version 6.1.0-3, the brltty package is optional.
After qemu 6.1.0-5 hits the Manajro stable repository, brltty can be removed. Unless of course you need it for your braille keyboard.


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