Mux Shield II (MuxShield.h)

http://mayhewlabs.com/products/mux-shield-2 -- Sometimes you need extra inputs and outputs on your Arduino; maybe you’re taking readings from dozens of sensors or controlling a bunch of LEDs. Whatever it is, the Mux Shield will help you out. Stack it onto your Arduino and you’ve just added 48 extra I/O pins. You can select whether the pins are analog inputs, digital inputs, or digital outputs. The Mux Shield uses a clever combination of multiplexers, shift registers, and control signals to accomplish this but don’t worry – it’s all wrapped up in a easy-to-use library that comes with examples. Have a look at the User Guide below for much more information.