8*8 Single and Bi-Color Led Matrix Pin Configuration with max7219

Overview

In this tutorial, we will learn how to interfacing single and bi-color 8*8 dot matrix display using max 7219 with Arduino Uno. It also called led matrix display. Nowadays, the most common and popular display is led matrix display. A led matrix display is a 2D(two dimensional) patterned led array. Generally, it is used to display any characters, symbols, and images. 

You can watch the following video below:-

Components Required

The following component needed for this tutorial:-

• Arduino Uno
• 8*8 Single Color Display
• 8*8 Bi-color Display 
• Max 7219 IC
• 15k Resistor
• 47uf Capacitor
• 0.1uf Capacitor
• Breadboard
• Some Jumper Wire

Dot Matrix Display Pinout

Single color led matrix has 16 pins. The pin configuration has been given below:-

Fig 1.1: 16 Pins Single Color Display Display

Bicolor led matrix has 24 pins. The pin configuration has been given below:-

Fig 1.2: 24 Pins Bi-color Display Pinout

Max7219 Pinout

The Max 7219 has 24 pins. The following below figure shows max7219 pin configuration.

Fig 2.1: Max7219 pinout

Circuit Schematic 

The circuit diagram of the led matrix display and Arduino interfacing below:-

Fig 3.1: Arduino and dot matrix display interfacing

Circuit Description

The single color 8*8 led matrix display has 16 pins. 8 pins are used to control 8 different rows. Rest of the 8 pins are used to control 8 different columns. Fig 1.1  shows the row and column pin number of the 8*8 single color display.

A typical 8x8 bi-color matrix display has two colors red and green. Thay has 24 pins. 8 pins are used to control 8 different columns. Rest of the 16 pins are used to control 8 different columns. 8 pins for red color and the remaining 8 pins for green color. Fig 1.2  shows the row and column pin number of the 8*8 bi-color display.

To control a led matrix display we need to 16 I/O pins of a microcontroller. Max7219 driver ic is used to reduce the use of microcontroller I/O pins. They have 24 pins(Fig 2.1). By using this driver it will be controlled by three I/O pins of a microcontroller.

The circuit will be connected to following below:-

Max7219 Driver                              Dot Matrix Display

Pin_2       -----------------------      Row_1

Pin_3       -----------------------      Row_4

Pin_5       -----------------------      Row_6

Pin_6       -----------------------      Row_2

Pin_7       -----------------------      Row_3

Pin_9       -----------------------      Row_7

Pin_10       -----------------------     Row_5

Pin_11       -----------------------     Row_2

Pin_14       -----------------------    Clm_7

Pin_15       ----------------------      Clm_2

Pin_16       ----------------------      Clm_6

Pin_17       ----------------------      Clm_1

Pin_20       ----------------------      Clm_5

Pin_21       ----------------------      Clm_3

Pin_22       ----------------------      Clm_8

Pin_23       ----------------------      Clm_4

• The 22uf and 47uf capacitor will be connected between 5v and GND.
• Pin 18 will be connected to 5v through a 15k resistor.
• Max7219 Vcc (Pin 19) to 5V Pin of Arduino.
• Max7219 GND (Pin 4 and 8) to GND Pin of the Arduino.
• Max7219 DIN(Pin 1) to Digital Pin 11 of the Arduino.
• Max7219 CS (Pin 12) to Digital Pin 10 of the Arduino.
• Max7219 CLK (Pin 13) to Digital Pin 13 of the Arduino.

Source Code 

The source code is given below:-

       #include <MD_Parola.h>   
  #include <MD_MAX72xx.h>   
  #include <SPI.h>   
     
  // Define the number of devices we have in the chain and the hardware interface   
  // NOTE: These pin numbers will probably not work with your hardware and may   
  // need to be adapted   
  #define MAX_DEVICES 1   
  #define CLK_PIN 13   
  #define DATA_PIN 11   
  #define CS_PIN 10   
     
  char ABC[]={'1','2','3','4','5','6','7','8','9','0','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','A','B','C','D'};   
  // Hardware SPI connection   
  MD_Parola P = MD_Parola(CS_PIN, MAX_DEVICES);   
  // Arbitrary output pins   
  // MD_Parola P = MD_Parola(DATA_PIN, CLK_PIN, CS_PIN, MAX_DEVICES);   
     
  void setup(void)   
  {   
  P.begin();   
     
  }   
     
  void loop(void)   
  {   
     
  for (int i=0;i<=sizeof(ABC);i++)   
  {   
  int x = ABC[i];   
  P.write(x);   
  delay(1000);   
  }   
  }   

You can download the library from here:- 
https://github.com/MajicDesigns/MD_MAX72XX
https://github.com/MajicDesigns/MD_Parola