Description:1:  MAX7219 is an integrated serial input / output common-cathode display drivers, which connects the microprocessor 7-segment digital LED display with 8 digits, you can also connect a bar graph displays or 64 independent LED. On which includes a B-type BCD encoder chip, multi-channel scanning loop, segment the word drive, but also an 8 * 8 static RAM for storing each data. Only one external register is used to set the segment current of each LED.2: 0.36" 4 digit led display 7 seg segment Common cathode Red3: The module is compatible of 5V / 3.3V microcontroller; Only three IO ports are used to drive the eight digit display.4:The devices include a 150µA low-power shutdown mode, analog and digital brightness control, a scan-limit register that allows the user to display from 1 to 8 digits, and a test mode that forces all LEDs on5: Only three IO ports are used to drive the eight digit display. MAX7219 supports flicker free displays as well as cascading displays; PCV board four corners of the fixed copper stud, which can effectively precent short circuit accidents happenConnection:  VCC→5VGND→GNDDIN →P00CS →P01CLK→P02Note: VCC and GND can not be reversed, otherwise it would burn the chip.Package Including:3 x MAX7219 7-Segment LED matrix