Expand your project possibilities, with the Adafruit PCF8575 GPIO Expander Breakout - an affordable 16 channel I2C expander.GPIO expanders work like this: you have a board with some number of GPIO but not enough for your project - maybe you need more buttons or LEDs. You could upgrade to a board with massive number of GPIO like the Grand Central, or you could pop on one of these boards. Connect it over I2C and then you can send/receive I2C...