The MAX7219 is an integrated serial input/output common cathode display driver that connects a microprocessor to an 8-bit, 7-segment digital LED display, as well as to a line graph display or 64 individual LEDs. It includes an on-chip B-type BCD encoder, a multi-scan loop, a segment word driver, and an 8*8 static RAM to store each data. Only one external register is used to set the segment current of each LED.

A convenient four-wire serial interface allows connection to a general-purpose microprocessor. Each piece of data is addressable and can be updated without rewriting all the displays. the MAX7219 also allows the user to choose to encode or not encode each piece of data.
The device includes a 150µA low-power shutdown mode, analogue and digital brightness controls, a scan-limit register that allows the user to display 1-8 bits of data, and a detection mode that allows all LEDs to be illuminated.

Only 3 IO ports are needed to drive 1 dot matrix! Flicker-free dot matrix display! Supports cascading!

 Module parameters:

1. A single module can drive a 8 * 8 common negative dot matrix

2. Module operating voltage: 5V

3. Module size: length 3.2cm X width 3.2cm X height 1.3cm

4. With 4 fixed screw holes, hole diameter 3mm

5. Module with input and output interfaces, support multiple modules cascade

Wiring instructions:

1. The left side of the module is the input port, the right side is the output port.

2. When controlling a single module, you only need to connect the input port to the CPU.

3. When multiple modules are cascaded, the input of the first module is connected to the CPU, the output is connected to the input of the second module, the output of the second module is connected to the input of the third module, and so on...

Take 51 microcontroller as an example:

VCC → 5V

GND → GND

DIN → P2.0

CS → P2.1

CLK → P2.2