Legend Orientate your Pi with the GPIO on the right and the HDMI port(s) on the left. GPIO (General Purpose IO) SPI (Serial Peripheral Interface) I2C (Inter-integrated Circuit) UART (Universal Asynchronous Receiver/Transmitter) PCM (Pulse Code Modulation) Ground 5v (Power) 3.3v (Power) Pinout! The Raspberry Pi GPIO pinout guide. This GPIO Pinout is an interactive reference to the Raspberry Pi GPIO