Adafruit sells a $15 board to let you use spi, i2c and gpio over USB. It also has their connector for easy i2c expansion with their family of sensors and breako

Adafruit sells a $15 board to let you use spi, i2c and gpio over USB. It also has their connector for easy i2c expansion with their family of sensors and breakouts. https://www.adafruit.com/product/2264 https://www.adafruit.com/product/2264