USB to Serial cable

[Jan_Mechelen]

Hello,

I bought a verry cheap USB to Serial cable (blue connectors and a transparant wire with silver shielding).

The cable works fine on Windows 10 (tested with loopback dongle and Putty). When I insert the cable with loopback dongle in my RPi3 (Rasbian - Jessie) everything looks ok. When I start a Putty terminal session on RPi3 the terminal windows opens but nothing is displayed when I type in characters. I assume it's a Linux driver problem.

Did somebody make this cable work under Raspbian - Jessie?

lsusb
Bus 001 Device 008: ID 1a86:7523 QinHeng Electronics HL-340 USB-Serial adapter

dmesg
[ 4565.114200] usb 1-1.4: new full-speed USB device number 8 using dwc_otg
[ 4565.217331] usb 1-1.4: New USB device found, idVendor=1a86, idProduct=7523
[ 4565.217354] usb 1-1.4: New USB device strings: Mfr=0, Product=2, SerialNumber=0
[ 4565.217367] usb 1-1.4: Product: USB2.0-Ser!
[ 4565.222276] usb 1-1.4: ch341-uart converter now attached to ttyUSB0

All help is appreciated!

[DirkS]

Unsure what you are trying to do...

Are you trying to connect from a Windows computer to your Pi or the other way around?
The info you give (lsusb, dmesg) suggests you are trying to connect *from* your Pi, but the use of Putty suggests otherwise.

[Jan_Mechelen]

I want to connect the Pi to my home domotics system that only has a RS232 interface, therefore I need a working cable/driver.

I installed Putty on my Windows10 PC -> cable works
I installed Putty on RPi -> cable does't work

[FTrevorGowen]

I want to connect the Pi to my home domotics system that only has a RS232 interface, therefore I need a working cable/driver.
I installed Putty on my Windows10 PC -> cable works
I installed Putty on RPi -> cable does't work

FWIW, I normally only use PuTTY to connect via SSH methods and prefer to use GtkTerm for serial connections & basic loopback tests (via Linux):
https://www.cpmspectrepi.uk/raspberry_p ... pters.html
https://www.cpmspectrepi.uk/raspberry_p ... apter.html
https://www.cpmspectrepi.uk/raspberry_p ... rtRep.html
Just OOC is it a TTL level (3.3V or 5V) or full RS232 "system"? Any hardware handshaking to be "fudged"?
Trev.

[hansotten]

The OP is having a CH341 Serial to USB adapter and has a loopback installed if I read his post correctly.

In Windows 10 it works, so the device is functional.

I have read reports (e.g. http://paulbyford.blogspot.nl/2016/03/u ... vices.html) and seen myself that the CH341 in current Jessie works, as tested with Minicom.
The OP seems to have a working driver also:
[ 4565.222276] usb 1-1.4: ch341-uart converter now attached to ttyUSB0

Make sure hardware handshaking in your terminal emulator is off, it may be on by default.

The 3.3V/5V issue is not yet relevant for the Raspberry Pi side, since this is just a loopback test.

[Jan_Mechelen]

I used exactly the same settings in Putty for Windows as in Putty for Raspbian. 8 data bits, 1 stop bit, no parity, no flow control, 9600.

I assume the cable (with CH340 chip?) is not compatible with that driver.

[scruss]

Jan,

The message

Code: Select all

ch341-uart converter now attached to ttyUSB0

indicates that the kernel found a driver, and has the device ready for you at /dev/ttyUSB0

Is your pi user a member of the dialout group? You need that for serial access. Do this, then log out and back in again:

Code: Select all

sudo usermod -a -G dialout pi

The loopback dongle - what is it? A simple RX/TX cross in the DB9?

Personally, I find minicom or screen more straightforward than using PuTTY's pterm. Typically, 9600 8N1 connection with screen would work with:

Code: Select all

screen /dev/ttyUSB0 9600

[Jan_Mechelen]

Hi Scruss,

Thanks for the help but no success

1. The loopback dongle has indeed tx/tx connected ( following pins are connected1-4-6 and 2-3 and 7-8-9)
2. Dialout belongs to the pi user group (if I type "id" it shows a list of groups with "20(dialout)" )
3. I installed screen and typed your command. Unfortunately the same results as with Putty.

[scruss]

Can you borrow/use another USB-Serial adaptor to see if the fault is elsewhere?

[Jan_Mechelen]

Problem solved!

I downloaded the driver code from the manufacturers website (http://www.wch.cn/download/CH341SER_LINUX_ZIP.html) and rebuilt the driver. After that it worked immediately.

It seems there is a probem with the built in driver ch341.ko in raspbian version 4.4.12-v7+

[Abbiati]

Hi, I've downloaded the file but i don't understand how i can rebuilt the driver.
Can you explain me?

[liudr]

I have Jessie from 2016-05-27 and mine works fine with ch340/1 with exact same VID/PID as yours. Mine is on an arduino nano and I've been able to communicate with it both ways. I'm not an expert but I wonder if someone can tell me how to tell the version of driver etc. so I can compare with OP's compiled driver.