[A]

[B]

Description:
MAX7219 is an integrated serial input / output common-cathode display drivers , which connects the microprocessor 7-segment digital LED display with 8 digits , bar graph can also be connected monitor or 64 separate LED. On type B BCD encoder includes an on-chip , multi-channel scanning loop , segment word drive, but also a 8x8 static RAM for storing each data . Only one external register is used to set the segment current for each LED.
A convenient four-wire serial interface can connect all common microprocessor. Each data can be addressed in the update does not overwrite all of the display . MAX7219 also allows the user to select each of the data code or not coded.
The entire device includes a 150A low-power shutdown mode , analog and digital brightness control , a scan-limit register allows the user to 1-8 bits of data , there is an LED light so that all the detection mode.

Wiring instructions:
1,Module on the left as an input port, output port on the right.
2,Control of a single module, simply input port to the CPU
3,more modules cascade input termination module of a CPU, 2 output termination module input and output of the two modules is terminated with the input end of the first three modules, and so on.

51 MCU, for example:
VCC → 5V
GND → GND
DIN → P22
CS → P21
CLK → P20

Package list:
2 X MAX7219 dot matrix module
2 X DuPont line 5pin
Notice:
Requires only three IO ports can drive a dot ! No flashing dot matrix display ! Support cascade !