DVK521 is a Cubieboard expansion board with many expansion interfaces supporting external module connection. Core interface introduction: core board slot: convenient to connect with Cubieboard; OV7670 interface: connects with OV7670 webcam module; 8I/Os interface: connects with all modules controlled by I/O; SPI interface: connects with modules with SPI interface such as AT45DBXX Dataflash module; I2C interface: connects modules with I2/C interfaces such as PCF8574 expansion board PCF8563 RTC module; USB interface: USB TO UART convenient to debugging program; VGA interface: connects with VGA display module; Capacitor touch screen slot: connets with capacitor touch screen with I2/C; 7" LCD slot: connects with 7" LCD; 1-Wire interface: connects with 1-WIRE devices (TO - 92 encapsulation) such as temperature sensor DS18B20 electronic registration code DS2401 module; UART interface(PL2303TA): connects with Cubieboard UART interface. Other interfaces introduction: Cubieboard pin: leads out Cubieboard pin interface convenient to use. 5V/3.3V power supply input/output interface: used for external power supply or user plate processing; Device introduction: power supply LED user LED buzzer user button rocker with up and down left and right enter fiver states; PL2303TA USB TO UART chip; 12M and PL2303TA crystal oscillator. Others: five direction rocker bar cable 1-WIRE jumper cable buzzer cable user jumper cable. Directions for use: short type jumper cable: connects with I/O by the specified sample program; Cur-off jumper cable: connects with user-defined I/O. 2.5mm welding plate: convenient for DIY.