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December 2022

December 5, 2006

Graphical LCD Project

Filed under: Electronics,Robots,Software — Bob @ 10:13 pm

cfax_large.jpgI’ve been playing with the CFAX 128 x 64 pixel graphical LCD from Spark Fun. This is a really nifty graphical display that includes a four-wire resistive touch screen and white backlight. The picture here (click it to see the larger version) has the backlight turned off and you can see it’s still pretty visible.

I decided to write some simple code to draw text and rectangles. The picture shows that stuff pretty well. I also got the touch screen logic working but that isn’t really demonstrated in the picture.

I’ve hooked it up to an AVR Mega 88 on a prototyping board, which gives just barely enough output pins to drive it. I will probably switch to a 40-pin Mega 16 to complete my experiments, as I want to use it with my on-going CAN project; it will require a few more i/o pins that what the 28-pin Mega 88 has available. The idea is to make the LCD available to all CAN nodes in a larger, multi-processor robot suitable for the SRS Robomagellan contest or something similar.

The display has its own memory buffer for the 128 x 64 pixel grid and also has about ten different icons above the top row. It’s pretty simple to interface, and fortunately Spark Fun has some useful sample code here. I also found some sample code from the original manufacturer here.

I also found a nifty article in a recent Circuit Cellar that gave me some inspiration. Look for the issue that covers various video, LCD and LED display projects. My long-term goal is to assemble all of my AVR software into an open source package under the GPL. When I get around to doing it I’ll post it here.


  1. GUUUAAAUUU it is amazing project, good job

    Comment by Rafael Sobrevilla — December 28, 2006 @ 10:44 pm
  2. Thanks Rafael! I hope to use this display on my next maze robot for Robothon.

    Comment by Bob — December 29, 2006 @ 11:03 am
  3. Good Idea!
    I Hope see it !
    What type of sensor use Lego Maizer? I don’t saw this on the last Robothon

    Comment by Rafael — January 3, 2007 @ 10:26 pm
  4. I’ve assembled my library of code (including something for the CFAX LCD) over here.

    Comment by Bob — December 6, 2007 @ 8:37 pm
  5. I am using the same LCD on a project for school, I was wondering if you can send me (or post) the circuit schematic between the LCD and the micro controller? Also, do you know if there is any more information, besides the data sheets from the manufacturer. Before hand thank you.

    Comment by Eric — October 7, 2009 @ 5:17 pm
  6. hi,the idea is great ………..
    i am working on the similar kind of project.can u tell me wat a touch can do in ur project?

    Comment by chandra shekhar — January 16, 2010 @ 8:02 am
  7. Hi Chandra, the sample project uses touch input to move between the three different demos (text, graphics, images). Each demo page is displayed until a “touch event” is seen (e.g. user touches the screen), then the next demo page is displayed. It wraps around such that text->graphics->images->text etc. The sample code does read the X/Y location of the touch but doesn’t attempt any sort of position calibration. Thanks for your interest!

    Comment by Bob — January 16, 2010 @ 12:03 pm
  8. hi,
    in ur project touch screen film and lcd(73.5×38.8mm) are in exact size.which standard (size) touch screen film u r using?(WxL) or inches

    Comment by chandra shekhar — January 20, 2010 @ 5:21 am
  9. Hi Chandra, the screen I used for this project had the touch screen integrated with the LCD. I don’t know if the touch-sensitive part is a standard size or custom to fit this screen. Its probably worth looking at the docs linked from the SparkFun site for details.

    Comment by Bob — January 22, 2010 @ 9:00 am
  10. Spammers have discovered a fascination with this post. If you are interested to discuss this topic more please contact me directly.

    Comment by Bob — April 1, 2010 @ 10:21 pm

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