DIY Kits
          Single module can drive an 8 * 8 dot matrix common cathode
          Module Operating voltage: 5V
          Module dimensions: length 3.2 cm X 3.2 cm wide X 1.3 cm high
          Holes with four screws, diameter 3mm
          Modules with input and output interfaces, support for cascading multiple modules
          Wiring instructions:
          On the left block to an input port, an output port on the right
          When the control of a single module, simply enter the port received a CPU
          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 → P20 
          CS → P21
          CLK → P22