is an integrated serial input / output common-cathode display driver, which connects your microprocessor to a 7-segment digital LED display with 8 digits; digital display control module, you can use it for Ar-duino. The module is compatible of 5V / 3.3V microcontroller; Only three IO ports are used to drive the eight digit display. Only three IO ports are used to drive the eight digit display. supports flicker free displays as as cascading displays; PCV board four corners of the fixed copper stud, which can effectively precent short circuit accidents happen. Wiring instructions (a , for example, you can pick any IO port definition can be modified in the ): VCC to 5V, GND to GND, DIN to P00, CLK to P02, to P01; Digital tube is 0.36 inch 4-bit integrated cathode digital tube; Common cathode. Note:VCC and GND do not reversed, it would burn the chip.51 MCU P0 port requires pull-up resistor, if your device does not have a pull-up resistor can be connected to other ports data lines. Material:PC+metal colour:Blue Package Contents: 4 x 8 bit digital display module Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real . The measurement allowed is +/- 1-3cm.