The I2C/TWI pins on the Micro are on D2 and D3. For Arduino beginners, these two boards are nearly interchangeable, especially when used in simple circuits like the Arduino's built-in examples.

I2C expanders, or ADCs will give you plenty of pins for whatever project you have in mind. All these require extra components, though. Enter the ExtraCore library for Arduino, a software library ...

[Rod] has decided to write up his method of using two Arduinos and the I2C protocol to expand an Arduino’s IO capacity. As seen in the picture above, you’ll sacrifice 2 analog pins, but if you ...