DIY Vex LCD Display

The LCD display can be used to display sensor and motor telemetry from Vex/Vexplorer robots that are running in autonomous mode where a laptop display is not convenient. Since I received good feedback from the DIY Vex LCD Display image that I posted on the Vex gallery, I thought I would start this thread to provide instructions to build it and asking for suggestions and help from other Vex forum members to improve it. The link to my working LCD Display connected to a Vex Controller is shown using the following link:

Currently it takes about 1 evening to build the LCD Display, if you have all the necessary electronic components including the LCD. The hardest part was writing the Easy C 2.0 LCD driver but I will supply it as a download for those of you are interested in building it or just examining the code to help improve it. I will also provide the connection diagram between the Vex Controller and the LCD Display and the Build of Materials (BOM). The LED BAR Display shown in the photo is not necessary for the LCD.

Connections to the Vex Controller digital outputs must be done carefully in order to avoid shorts.

Limitations: Currently I can only display text messages with the LCD display since I have not yet figured out how to display integer and floating point values, but I am working on this problem using both Easy C 2.0 and Microchip PIC18 C and MPLAB.

Cool display. I have one that I built based on a friends design. It uses a PIC chip to take serial input in and put display info out. The code allows you to send command sequences down to clear the screen, do bar charts, etc. It’s a simple circuit board to build with about 7 components on it.

Thanks! This display is directly connected to the Vex Microcontroller using its I/O pins, so as to keep the number of parts to a minimum and the cost low. I was able to use Easy C 2.0 and Microchip PIC18 C to display text on it, but now I am trying to display integer and floating point values so I am writing the necessary functions to do so.

I am also drawing the schematic necessary to build this LCD Display using the Student version of Eagle 5.2 schematic capture program and will upload it as soon as I complete it.

Maybe you can include photos and schematics of your serial LCD, does it require TTL levels (5 Volts) or does it use a level translator IC such as a MAX233? Can it do graphics as well as text?

Check out the schematic that I posted on the Vex Gallery showing how I made this DIY LCD Display using the Vex Controller. The firmware for driving it is written in PIC18 C using MPLAB. Photo of the LCD display and schematic are found using the following links.

I placed my working DIY LCD code in the Vex Code Archive so that anyone who wishes to build their own LCDs can use it to write messages to it. The firmware was written using Easy C Professional, although I also had another version similar to this one that used Easy C 2.0 except that it did not display integer values. Both the schematic and photo of the working DIY LCD Display is posted in the Vex Gallery. Be free to add to it to build an LCD library and just post the resulting code for the rest of the Vex Forum.

Please note that the RS pin is now 10 and the E pin is now 11, which is different from the schematic posted in the Vex Gallery. So if you build this LCD circuit just change the pin assignments accordingly or modify the easyC code back to the original values shown in the original schematic in the Vex Gallery at this location:



The June 2010 Issue of SERVO has a VEX article that shows how to build a DIY LCD and also includes information on the VEX LCD Module.