We have made further improvements since many customer feedback products have been turned up. The problem has now been improved!  Please rest assured purchase We need your voice, so our customers keep improving our shortcomings! The test program:   http://forum.mhetlive.com/topic/13/test-max7219-dot-matrix-module-with-arduino-uno MAX7219 Dot Matrix Module For Arduino Microcontroller 4 In One Display with 5P Line

Introduction: 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. Thereon 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. A 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. The entire device contains a 150μA low-power shutdown mode, analog and digital brightness control, a scan-limit register allows the user to display data bits 1-8, and one for all LED luminescence detection mode. It requires only three IO ports to drive a dot matrix! No flicker when the dot matrix display! Support cascading! Parameters:  1. A single module can drive a total of 8 * 8 dot matrix overcast 2. Working voltage: 5V 3.  Size: *12.8 cm*3.2 cm *1.3 cm (L*W*H) 4. With 64 fixing screw holes, diameter 3mm 5. module with input and output interfaces, support for cascading multiple modules Wiring instructions:  1. The left side of the module as an input port, an output port on the right. 2. If a single control module, simply input port connected to CPU 3. cascading multiple modules, input and output termination CPU, input the output end of the second module of the first module, the first two modules of the first three input termination module, and so on. .. 51 microcontrollers, for example: VCC → 5V GND → GND DIN → P2.2 CS → P2.1 CLK → P2.0 Shipping list: 1.MAX7219 dot matrix module  (tested well) 2.20CM Dupont line*5P