635 and Linux


New member
Hello, my question is quite simple: would I be able to use the CFA-635 USB display under Linux? Is it possible to interface with CFA-635 in the same way as with CFA-633, if I'm writing my own software?
I have searched this forum and haven't been able to find any information regarding CFA-635 under Linux.
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CF Tech

Yes, the CFA-635 will interface to Linux just like the CFA-633, except the baud rate will be 115,200 by default instead of 19,200 by default for the CFA-633 (either display can be set to 115,200 or 19,200 though).

The CFA-631/CFA-633 Linux test program:


should work, just use the section intended for the CFA-631. We will get an update going on that shortly.


New member
CFZ-635 / Linux / Custom characters

Is there a code snippet showing how custom characters are uploaded to the 635 in linux?

-Martin B


New member
notes on 635 and linux

I'm finishing up a series of demonstration programs for the 635, and I have to say that it was a breeze getting it up and running.

I'm working on releasing two programs soon that will provide plenty of example code for people to learn on, as well as provide a more generic method to control the display under linux.

In any case, one important note -- >

The 633 display uses two commands to send text to line one and two of the display. This has been OBSOLETED in the 635. You must use the new command 31.

I'll post an edited version of the 631/633 demostration program as well, which supports the change.


New member
I am eager to see your work regarding the 635.

I am working on a bus arrival display using the 635.


New member
I run:

./test633 /dev/ttyUSB0 19200 clear

this is the output:

Ultra-simple CFA-631 / CFA-633 / CFA-635 command-line communications example.
Crystalfontz America, Inc. http://www.crystalfontz.com

./test633 PORT BAUD
PORT is something like "/dev/ttyS0" or "/dev/usb/ttyUSB0"
BAUD is 19200 or 115200
To clear the display, enter "clear" as an optional third parameter

Serial_Init:: success
"/dev/ttyUSB0" opened at "19200" baud.

Ctrl-C to exit.
Updated display, now waiting for packets

Display Cleared.

but the display is not cleared... any ideas?


CF Web

You are still using the 19200 baud rate as your parameter rather than the 115200 which is why the program is not communicating with the module. (The new 635 version defaults to 115200 baud rather than 19200, as is the case for the 633 demonstration code)

I modified the 633_linux for the 635 and put the new version here: http://www.crystalfontz.com/products/635/635_linux.tar.gz

Give it a try and feel free to let me know if you have further questions.


New member
sweet, that did it, i am now able run the test succesfully.

now as far as programming interfaces and linux, do you have any recomendations?

i want to have a meny driven interface to display a few different bus times. i will probably write it in python or ruby, any advice is helpful.

i know there is lcd4linux and lcdproc, but interested in ideas for approach.

thanks again.