LK204-25-USB woes on Fedora Linux

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AndyWas
LCD?
Posts: 3
Joined: Tue Nov 04, 2014 1:50 pm

LK204-25-USB woes on Fedora Linux

Post by AndyWas » Tue Nov 04, 2014 2:15 pm

Hello,

I have a Matrix Orbital LK204-25-USB running on Fedora 20 64-bit (kernel 3.16.6-203.fc20.x86_64). lcdproc is version 0.5.6-6.

The device ID given by lsusb is "Bus 002 Device 003: ID 1b3d:0157" though there is no descriptor string - is it missing from usb.ids in the hwdata package?

When I start LCDd I get the following output to the system log file:

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ov 04 22:04:32 localhost.localdomain systemd[1]: Starting LCDd Service...
Nov 04 22:04:32 localhost.localdomain LCDd[7225]: MtxOrb: unable to read device type
Nov 04 22:04:32 localhost.localdomain LCDd[7225]: MtxOrb: unable to read device firmware revision
Nov 04 22:04:32 localhost.localdomain LCDd[7225]: MtxOrb: unable to read device serial number
Nov 04 22:04:32 localhost.localdomain systemd[1]: Started LCDd Service.
The system device is /dev/ttyUSB4, as identified by modprobe ftdi_sio. I have this configured in /etc/LCDd.conf, as well as
Type=lkd
(also tried "Type=lcd") and
hasAdjustableBacklight=no
The display goes bright all over when the system boots, but then goes dark and stays that way. I get the following output when I try to start lcdproc:

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Nov 04 22:18:13 localhost.localdomain systemd[1]: Starting lcdproc Service...
Nov 04 22:18:13 localhost.localdomain systemd[1]: lcdproc.service: control process exited, code=exited status=1
Nov 04 22:18:13 localhost.localdomain systemd[1]: Failed to start lcdproc Service.
Nov 04 22:18:13 localhost.localdomain systemd[1]: Unit lcdproc.service entered failed state.
Nov 04 22:18:13 localhost.localdomain lcdproc[7274]: sock_connect: connect failed
Nov 04 22:18:13 localhost.localdomain lcdproc[7274]: Error connecting to LCD server localhost on port 13666.
Nov 04 22:18:13 localhost.localdomain lcdproc[7274]: Check to see that the server is running and operating normally.
even though the settings in lcdproc.conf and LCDd.conf match. I saw some posts about this display on Linux, but all from several years ago so I assumed they wer all fixed now.

Grateful for any advice,
Andrew

Clark
Matrix Orbital
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Re: LK204-25-USB woes on Fedora Linux

Post by Clark » Wed Nov 05, 2014 10:56 am

Hi Andrew,

It looks like lcdproc is having trouble communicating to your display. I would recommend using echo commands within terminal to confirm that you are able to communicate to the display. Once you have confirmed communication, copy the settings over to your configuration files, specifically the speed.

Cheers,
Troy
Troy Clark
Design & Development
Matrix Orbital

AndyWas
LCD?
Posts: 3
Joined: Tue Nov 04, 2014 1:50 pm

Re: LK204-25-USB woes on Fedora Linux

Post by AndyWas » Wed Nov 05, 2014 1:15 pm

Hi Troy,

Sorry for sounding dumb, but what sort of echo commands should I run? Do you mean something like:-

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echo 'Hello World!' > /dev/ttyUSB4
That doesn't generate any output, either in the terminal window or system log.

NB: I should confess that I can't actually see the display...I'm away from home at the moment, trying to do some post-build fixes on our daughter's custom-job PC while I'm on the road! ;-)

Thanks,
Andrew

Clark
Matrix Orbital
Matrix Orbital
Posts: 859
Joined: Fri Aug 17, 2007 10:58 am
Location: Matrix Orbital
Contact:

Re: LK204-25-USB woes on Fedora Linux

Post by Clark » Wed Nov 05, 2014 3:40 pm

Hi Andrew,

No worries, I understand that without being able to see the screen it will be difficult to debug with a simple string. You might try using echo to send a command such as Read Module Type (254 55) which should provide a response if successful. Your code snippet looks good.

To send characters that don't appear on the keyboard, like 254, try holding the left ALT key and typing their 4 digit decimal value on the number pad at the right of your keyboard.

The default baud rate of the display is 19200, and you can force it to that setting through a hardware manual override. If the display is not accessible, you might try sending commands via echo at different baud rates until you get a response.

Cheers,
Troy
Troy Clark
Design & Development
Matrix Orbital

AndyWas
LCD?
Posts: 3
Joined: Tue Nov 04, 2014 1:50 pm

Re: LK204-25-USB woes on Fedora Linux

Post by AndyWas » Sun Nov 16, 2014 8:31 am

Hi Troy,

Thanks for this - I found the description of these command strings in the manual, but not sure if I am entering them correctly. I tried

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echo 254 55 > /dev/ttyUSB4
If I used the Alt + NumKeys method I got

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(arg: 254) echo 
Not sure how Windows-specific this is...I am using Konsole on Fedora 20. I also tried using hex representation (i.e. 0xFE 0x37) and all combinations with single, double and no quotes. With none of these did I get any response, either back on the command line or in the system log. Sorry for being such a doofus but could you give me a sample of the exact string I should enter on the command line?

Given the outputs I do get, as described in the OP, is it possible that the display has got damaged? I found some posts advising careful handling, but they were all from several years back and this one was purchased at the end of last year. I recall that originally it displayed the "Matrix Orbital" logo on startup before going blank, but at some point (can't recall exactly when) it just went bright all over before again going blank. Admittedly the PC is a custom job (it's a converted biscuit tin) but I have building computers for 20+ years and always follow anti-static precautions, and the display hasn't been moved since it was installed - when it did at least show the logo. It's connected using a normal cable from the Mini-USB port to one of the M/b headers. I guess doing a hardware reset by shorting the pins on the keypad connector would be a good idea, but I can't do that right now as I don't have physical access.

Thanks,
Andrew

Clark
Matrix Orbital
Matrix Orbital
Posts: 859
Joined: Fri Aug 17, 2007 10:58 am
Location: Matrix Orbital
Contact:

Re: LK204-25-USB woes on Fedora Linux

Post by Clark » Mon Nov 17, 2014 8:57 am

Hi Andrew,

My apologies, it's been a while since I've worked with a Linux terminal. The code below will clear the screen for a unit connected to ttyUSB1 at 19200 baud. You can also ask the unit for its module ID in this way, but unfortunately, the response appears on the LCD rather than the terminal.

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echo -e "\xFE\x58" > /dev/ttyUSB0
I would recommend viewing our Linux AppNote for an overview of how to communicate to your display in the Linux environment. Also, if you could troubleshoot from within the same room as the display, that would help a great deal.

Cheers,
Troy
Troy Clark
Design & Development
Matrix Orbital

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