Wiring instructions: 
1. On the left block to an input port, an output port on the right. 
2. When the control of a single module, simply enter the port received a CPU 
3. When more than 3 modules cascaded output input termination CPU, the input output termination module of the first two modules of the first one, the first two modules of the termination input terminal of the three modules, and so on. 

To 51 single example: 
VCC → 5V 
GND → GND 
DIN → P2.2 
CS → P2.1 
CLK → P2.0

Package included: 
3* MAX7219 Dot Matrix Module