IOstrich GPIO Shield

The IOstrich GPIO Shield adds 40 I/O pins to the Arduino platform. It uses the I2C ("Wire") bus on the Arduino, leaving all digital pins free for your own use (except one, if interrupt support is used).  Each I/O pin has configurable interrupt-on-change support, and pins can source/sink 10/15mA each.  Overall shield current limits are such that 15mA can be sunk off every pin on the shield at once without causing any problems.  Voltage levels for the shield are selectable between 3.3v and 5v, and the shield is 5v tolerant in either mode.  Up to 8 of the shields can be stacked together, allowing for the addition of up to 320 I/O pins.

Documentation and resources for the IOstrich GPIO Shield can be found at the IOstrich product information page.