KNACRO 8 Digital Display Module, MAX7219 Digital Display Control Module, Supports Cascading Eight Three Serial IO Port Control MAX7219 is an integrated serial input / output common-cathode display driver, it connects the microprocessor 7-segment digital LED display with 8 digits, you can also connect a bar graph display or 64 independent LED. Including a B-type BCD encoder chip, multi-channel scanning loop segment word driver, but also a static RAM 8 * 8 for storing each data. Only one external register is used to set the segment current of each LED. Convenient four-wire serial interface can be connected to all general-purpose microprocessor. Each data can be addressed in the update do not need to rewrite all of the display. MAX7219 also allows each user to select a data coding or non-coding