Using the Maxim7219 with Arduino

A few weeks ago I setup my Arduino to power a simple single digit 7 segment LED array. It took lots of pins from the Arduino (one per segment) to power it. Nice simple setup but I knew it would never work for powering more than a single 7-segment digit. I found the Maxim 7219 which is a chip designed specifically to drive LED arrays. It’s really a neat device (although a bit expensive). I decided I’d pick up some 7291’s from Jameco (I often switch between them and Digi-Key) and picked up a few of thier 4 digit 7-segment LED arrays (common cathode) as well to test the IC out. You’ll definitely want to take a look here which outlines the library used, basic schematic and the really important calculation of the RSet value. I’ve included a demo sketch, high-res pictures and the Maxim 7219 datasheet in the ZIP file below.