MCP23017-I2C 16 I/O Ports Expander

Add another 16 pins to your microcontroller using an MCP23017 port expander. The MCP23017 uses two I2C pins (these can be shared with other I2C devices), and in exchange gives you 16 general purpose pins. You can set each of the 16 pins to be input, output, or input with a pullup. There's even the ability to get an interrupt via an external pin when any of the inputs change so you don't have to keep polling the chip.

Use this chip from 2.7-5.5V (good for any 3.3V or 5V setup), and you can sink/source up to 20mA from any of the I/O pins so this will work for LEDs and such. Team it up with a high-power MOSFET if you need more juice. DIP package means it will plug into any breadboard or stripboard.

You can set the I2C address by tying the ADDR0-2 pins to power or ground, for up to 8 unique addresses. That means 8 chips can share a single I2C bus - that's 128 I/O pins!

This chip can be used in RGB LCD + Keypad shield to control an LCD and read a 5-way keypad. It is very reliable and easy to get it up and running. There's also an Arduino library with example code written which will set pin state, read and write from individual pins, and set the pull-ups.

• 16-bit remote bidirectional I/O port
• 28 pins
• Package: PDIP (Plastic Dual In-line Package)
• High-speed I2C interface
• Three hardware address pins to allow up to eight devices on the bus
• Configurable interrupt output pins
• INTA and INTB can be configured to operate independently or together
• Configurable interrupt source
• Polarity Inversion register to configure the polarity of the input port data
• External Reset input
• Low standby current: 1µA max.
• Supply Voltage Min: 1.8V  
• Supply Voltage Max: 5.5V
• This board/chip uses an i2c 7-bit address between 0x20-0x27, selectable with jumpers

Packing list:

• 1 x MCP23017 - I2C 16 input/output Port Expander