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Arduino output multiplier: What's a good way to get more pins on my Arduino? Answered

I want more outputs for my Arduino Duemilanove. I want to run a simple 16x16 LED matrix but I'd need more pins. Most instructions I find use one of several chips such as the 7442 1 of 10 decoder IC, another option might be a couple of 4017 decade counters.

Can anybody recommend a method that is widely used and well documented?


 74hc595 shift registers.  They can be cascaded, and a dozen of them can run on the same 3 pins, each with 8 outputs.  A higher current version is available.  It costs $3 on eBay for 10 of them, including shipping.

The arduino site is a good start. This article explains how to multiplex and demux and includes some code.