Peggy 2.0 Pegboard.

Peggy 2.0 Pegboard.

I bought a Peggy 2.0 LED pegboard from the evil mad scientist over at www.evilmadscientist.com. It's a fun little 25x25 array of LEDs driven by an AVR ATMega168. The LEDs are individually addressable but you can activate only one row at a time, so to make them all appear to light at the same time your software has to scan rapidly through the rows in sequence. By pulsing the LEDs on each row at different rates, you create a kind of low resolution grayscale display screen.
Evil, mad Windell Oskay wrote some demo programs for Peggy 2.0, including a nice version of John Conway's Game of Life, shown in the picture at the left. I wanted to see what else I could get it to do, so here are a few demos I wrote.

Click on the pictures below for the source files.

Last update: June 2006

No one will mistake Peggy for a digital picture frame, but it's amazing what you can do with 25x25 pixels and 16 shades of gray. I was originally going to add something like a 24C32 eeprom to store a bunch of pictures that Peggy could cycle through, but when I saw Honest Abe here, I thought what's the point? I'll just call this a proof of concept and leave it at that.

When I got my Apple II way back in '77, one of the first things I wrote for it was a simple little random line drawing program. Peggy's low res screen was just calling out for me to revive it. It's surprisingly entertaining to watch, the picture at the left doesn't really do it justice. I wonder how Pong would look running on a Peggy.

I like this one a lot. It runs on a stand-alone Peggy 2.0, using one of the ATMega168's timers to generate a timing pulse, or it can use a Dallas Semiconductor DS1307 chip to maintain the time (and date, but I don't display that). The advantage of the DS1307 is that it keeps running even when Peggy's switched off, so you don't have to set the time whenever you turn it on. The old-tech/new-tech hybrid nature of an analog clock running on an LED display makes it look like something that belongs in the movie Brazil.

Jun 22, 2008 - Version 2 - you can now control the brightness of the display using a light dependent resistor.