is an integrated serial input/output common cathode display driver, which connects your microprocessor to an 8-digit 7-segment digital LED display; digital display control module, you can use it for Arduino. The module is compatible with 5V / 3.3V microcontrollers; only three IO ports are used to drive the eight-digit large display. Only three IO ports are used to drive the eight-digit large display. Supports flicker-free displays as well as cascaded displays; the four corners of the PCV board have fixed copper pins, which can effectively prevent short-circuit accidents. Wiring instructions (e.g., you can choose any IO port definition that can be modified in): VCC to 5V, GND to GND, DIN to P00, CLK to P02, to P01; The digital tube is a 0.36-inch 4-bit integrated cathode digital tube; Common cathode. Note: VCC and GND must not be reversed, as this would burn the chip. 51 MCU P0 port requires pull-up resistors; if your device does not have a pull-up resistor, it can be connected to the data lines of other ports. Material: PC+metal Color: Blue Package Contents: 4 x 8-bit digital display module Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture to be slightly different from the real thing. The allowed measurement error is +/- 1-3 cm.