2x2 LED matrix
Posted Sun, Nov 28, 2004 at 08:18 PM
Yesterday was a sad day indeed... the main chip on my Basic Stamp got damaged ("Hmm, smells like burning?") and none of the downtown retailers sell the replacement part. Might even need to order it from a company in Calgary so it looks like I will be microcontroller-less for a couple of weeks.
I was working on the LED matrix component of this project. I found a couple of schematic diagrams here (16x16) and here (8x8).
I must admit that I'm not the best at reading these things so I decided to test out the 2nd diagram on a breadboard. Below are my results for a 2x2 matrix without using the hex inverter or shift register. (And I completely recommend adding the hex inverter before you try hooking it up to a Basic Stamp because the LEDs can draw a lot of power. Norm once wisely said: "Better a $2 4049 chip than a $50 Basic Stamp!" Oh, if only I had listened!)
Anyways, I need to double check on the placement of my transistor but it seems to work. Plugging and unplugging the 4 wires going into the postive power strip will allow you to light up a combination of LEDs to light up.
(Use the lines on the graph paper as a guide for where to place things on the breadboard.)
The key is figuring out how to connect all the negative leads of an LED column together in series and then getting all of the positive leads into rows. (On a breadboard, it will drive you nuts!!)
Next step is to add a few more columns and rows of LEDs and the shift register........