ch340g usb to ttl error: ch341-uart ttyUSB0: failed to read modem status: -110

im using Ubuntu 20.04.3 LTS

when i try to upload from arduino i get

avrdude: ser_open(): can't open device "/dev/ttyUSB0": Input/output error 

when i try to open serial monitor

Error opening serial port '/dev/ttyUSB0'. (Port not found) 

if i use another type of usb to serial (pl2303) serial monitor is working fine the hardware is working fine i tested on a windows machine and no problem.

$ lsmod | grep usbserial usbserial 53248 2 pl2303,ch341 

dmesg gives:

[ 451.329190] usb 10-2: new full-speed USB device number 2 using xhci_hcd [ 451.505205] usb 10-2: New USB device found, idVendor=1a86, idProduct=7523, bcdDevice= 2.54 [ 451.505219] usb 10-2: New USB device strings: Mfr=0, Product=2, SerialNumber=0 [ 451.505223] usb 10-2: Product: USB2.0-Serial [ 451.556668] usbcore: registered new interface driver usbserial_generic [ 451.556686] usbserial: USB Serial support registered for generic [ 451.558302] usbcore: registered new interface driver ch341 [ 451.559378] usbserial: USB Serial support registered for ch341-uart [ 451.559976] ch341 10-2:1.0: ch341-uart converter detected [ 451.573480] usb 10-2: ch341-uart converter now attached to ttyUSB0 [ 463.937493] usb 10-2: failed to receive control message: -110 [ 463.937504] ch341-uart ttyUSB0: failed to read modem status: -110 [ 482.625628] usb 10-2: failed to receive control message: -110 [ 482.625701] ch341-uart ttyUSB0: failed to read modem status: -110 [ 501.281699] usb 10-2: failed to receive control message: -110 [ 501.281710] ch341-uart ttyUSB0: failed to read modem status: -110 

and with pl2303:

[ 1751.189867] usb 10-2: USB disconnect, device number 2 [ 1751.190187] ch341-uart ttyUSB0: ch341-uart converter now disconnected from ttyUSB0 [ 1751.190220] ch341 10-2:1.0: device disconnected [ 1786.822056] usb 10-2: new full-speed USB device number 3 using xhci_hcd [ 1786.996937] usb 10-2: New USB device found, idVendor=067b, idProduct=2303, bcdDevice= 3.00 [ 1786.996946] usb 10-2: New USB device strings: Mfr=1, Product=2, SerialNumber=0 [ 1786.996951] usb 10-2: Product: USB-Serial Controller [ 1786.996954] usb 10-2: Manufacturer: Prolific Technology Inc. [ 1787.046337] usbcore: registered new interface driver pl2303 [ 1787.046367] usbserial: USB Serial support registered for pl2303 [ 1787.046410] pl2303 10-2:1.0: pl2303 converter detected [ 1787.076108] usb 10-2: pl2303 converter now attached to ttyUSB0 

I tried a lot of things like adding user to dialout and file permissions

what can be done?

edit:

ls -al /dev/ | grep ttyUSB* crw-rw---- 1 ss dialout 188, 0 dec 19 16:58 ttyUSB0 

same for both devices

edit:

after

sudo usermod -a -G dialout username && sudo chmod a+rw /dev/ttyUSB0 && sudo chown root:dialout -R /dev/ ls -al /dev/ttyUSB* crw-rw-rw- 1 root dialout 188, 0 dec 19 20:40 /dev/ttyUSB0 

arduino serial monitor same error and dmesg same as above

update:

installed arduino on another machine (same laptop with windows7 different hdd) only run the add user to dialout group and is working fine uploaded a test sketch from arduino. Same version "Ubuntu 20.04.3 LTS" The laptop is an older model only usb2.0 the pc is "newer" (5-6 years old) and using a usb3.0 port. Switch to a 2.0 port and now is better but other problem: serial monitor is picking up random characters at random intervals:

MCbK19:kEPUqPJv0Zyq71dlX19QDFDFR 2K19:m4GjpRJ7cNnR9AxB X19K19:M4yD0kmEvONihR79X19 DFUDK19:OVyzqIbEKK4VAUCcX19DF 

?????

i can upload a sketch if i manage to send between the random chars.

Problem resolved by using a USB2.0 port.

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