# Documentation ## 1.0 Keypad The kepad is driven by an io-expander. Thus it can be acessed over i2c. Adress 0x21 ### 1.1 Wiring * Red: 3.3V * Black GND * Green SDA -> D3 * Grey SCL -> D4 ## 2.0 LCD The LCD display is driven on the same i2c bus as the keypad.