Main Features:
● MAX7219 is a kind of integrated serial input / output common cathode display driver， it connects microprocessor and 8 digit 7 period of digital LED display， also can be connected to the bar graph display or 64 independent LED.
● It includes a piece of type B BCD coder， multiple scanning circuit， period of word drive， but also an 8 x 8 static RAM used to store every data.
● Only an external register used to set each LED segment current.
● A convenient four wire serial interface can connection all general microprocessor.
● Each data can be addressed in the update don't need rewriting all the display.
● MAX7219 also allows the user to each data selection coding or not to code.
● Only need three IO mouth can drive eight digital tube.
● Digital tube display when flicker free and it supports cascade.

Note:
● The VCC and GND don't pick back so as not to burn out chip.
● 51 SCM P0 port need connected to pull resistance， if your SCM not connected to pull resistance， can will data line received other port.