Features Arduino compatible, based on Seeeduino Onboard microcontroller: ATmega328P Onboard Real Time Clock chip with a supercap as a backup power source Serial interface with DTR for auto reset during programming when operating in standalone mode. (For programming, UartSBee must be bought separately) microSD card socket I2C Pin header (operation voltage is selectable: 5.0V or 3.3V) User defined switch and LED Bee series socket - 2*10 pin 2.0mm pitch (which will mate with - one at a time - any of the wireless modules: XBee, BluetoothBee, GPSBee or RFBee.) Please note that The IO Ports work in 0~3.3v level only.