TICI 1.0 Upcoming Programs Tutorial:
Giving Your TI Calculator A Color Screen



How It Works
This method of making the calculator screen color is very similar to 8-level grayscale used in some assembly programs. It uses three different colored LEDs, a red, green, and blue. Combined, they can make the following colors:

The screen goes through three cycles, a red, green and blue cycle. During each cycle, the LED for that color is on and the image that represents that color is onscreen. This means that every 1/20th of a second or so, the screen goes through one complete cycle of three colors. If a pixel is on during a color cycle, then that color does not show through; if it is off, then the color does show through. Because of the speed with which the colors are cycled, the colors will appear to blend to the human eye.

The LEDs are controlled through the link port. One of the lines is Clock (CLK) and controls whether the LEDs are on or off. The other line, Data (DTA), controls which LED is on. Each pulse through the Data line causes the circuit to flip to the next of the three LEDs. However, if the Clock line is low, none of the LEDs will be on.


The Plans and Instructions
To make your screen color capable, you have to open up your calculator; if you're squeamish about this, don't bother trying. IF you don't know the difference between a capacitor and a transistor, don't try it either. Here is the diagram for how to put the whole thing together:
Note: Author is not responsible for any harm to your calculator etc. resulting from building this device or anything related.
Materials:
(1) piece of plexiglass, AT MOST 2mm thick - get it as thin as you can
(1) mirror, same size as the plexiglass; also look for the thinnest you can find
(3) red LEDs
(3) green LEDs
(3) blue LEDs
(-) various wires
(1) soldering device

Steps:
  1. Make the controller circuit board and solder the necessary wires to it.
  2. Unscrew the back of the case of your calculator.
  3. When the case is open, remove the two screws near the bottom and take out the silver shield material
  4. Using double-sided foam tape, attach the controller circuit board to the calculator's main circuit board. Make sure that you completely cover the bottom of the circuit board with tape so that there are no short circuits.
  5. Find the power tracks on the main board; solder the power leads from the controller board so that power is only present when the calculator is on.
  6. Place the plexiglass and mirror as shown above.
  7. Connect the LEDs and secure them inside the calculator
  8. Connect the wires to the link port as shown
  9. Replace the silver shield, put the screws back in, and reattach the cover.
Schematic (Preliminary)Alternate Schematic
When you are done, afix the following label to the back of your calculator:

Click here to open in new window, then print
(c)2003 Kerm Martian