Check out the newest LED matrix shield here.
Updated Dec 18, 2010
A newer and better revision of the "Dual LED matrix shield" is available. Check it out here.
As of today, instead of the rotary encoder, the kit includes an infrared receiver, a tilt switch and two right-angle push buttons (see photos here).
... or, in other words, an Arduino shield that has two side-by-side, red-and-green 8x8 LED matrices. As probably everybody in the Arduino community knows by now, the most straightforward way to drive all these LEDs is through shift registers, specifically 74HC595. Which is exactly the way this shield is built: it has 4 of the 595 chip, each driving 8 columns of the same color. The 8 rows are connected to 8 output pins of Arduino (3, 7-13) through the ULN2803 transistor array.
The schematic is shown below (download Eagle file here).
This is the layout of the board (download Eagle file here).
The two LED matrices cover the components on the board and they get plugged into machined female headers for sturdy and reliable contact.
The LED matrix is UVP-2788 (datasheet here) and its internal circuit diagram looks like this:
This shield is used as part of the IllyClock. Originally it was designed to accommodate a push button and an infrared receiver, but these two components were dropped for an external (not on-board, but connected through wires) rotary encoder with push button.
You can buy the dual matrix shield here, as a kit containing the following parts (as seen in the photo below):
- two 8x8 bi-color bright LED matrices (side is 47mm or 1 7/8" in length, 5mm LEDs);
- 4 x 74HC595 shift registers;
- 4 x 16-pin socket;
- 32 resistors;
- 4 decoupling capacitors (100nF);
- 4 x 12-pin machined female headers;
- 40-pin male header;
- rotary encoder with push button and knob (not pictured).