DFR0566 IO Expansion HAT DFRobot DFR0566 IO Expansion HAT is an evaluation board for the Raspberry Pi 4B/3B+ that automatically configures the GPIOs and drivers of the board. This DFRobot expansion HAT leads out all IO ports, including digital, analog, PWM, IIC, UART, SPI, and IIS. The IO expansion HAT comes with 65mm x 56mm dimensions and offers a 5V operating supply voltage. This expansion HAT is compatible with the DFRobot Gravity series electronic toolkits.