The MCP23017 is a device that adds 16 new digital inputs or outputs to a microcontroller using I2C communication, so it does not even use new pins on a microcontroller assuming you have other I2C devices. This breakout makes it easy to use this chip with a standard I2C connector and pins that can be connected to a breadboard.

Thanks to the jumper on the board, it is possible to change the I2C address of the device and connect as many as 8 breakouts to one microcontroller. This would mean that you can get a maximum of 128 inputs/outputs out of 2 pins. There are also interrupt pins for the time precision changes of the pin states. All pins have built-in pull-up resistors that can be switched on or off.

• Voltage: 1.8V - 5.5V
• Maximum current per pin: 25mA
• Communication: I2C
• Pin number: 16
• Comes with a 20-pin header

This board has been manufactured in Croatia by e-r.io: Blog, Github