12. MAX7219 LED Matrix

The MAX7219 is an integrated serial input/output common-cathode display driver that connects your microcontroller to a 8-digit 7-segment digital LED display or a 8x8 LED matrix. It is especially useful when you need to control a large number of LEDs with minimal pin usage. In this tutorial, we will learn how to set up and use the MAX7219 LED matrix module with an Arduino.

Materials

Component	Image
Breadboard
Jumper wires
Arduino Uno R4 Minima
MAX7219 Module

Instructions

1. Make the following connections using the breadboard and jumper wires.

Connections

(MAX7219 to Arduino)

• Vcc to 5V
• GND to GND
• DIN to pin 12
• CS to pin 11
• CLK to pin 10

2. Download the LedControl library from the Library Manager in the Arduino IDE.

3. Paste the following code into your main Arduino sketch:

Code

#include <LedControl.h>

LedControl lc=LedControl(12,10,11,1);

/* we always wait a bit between updates of the display */
unsigned long delaytime1=500;
unsigned long delaytime2=50;
void setup() {
  /*
   The MAX72XX is in power-saving mode on startup,
   we have to do a wakeup call
   */
  lc.shutdown(0,false);
  /* Set the brightness to a medium values */
  lc.setIntensity(0,8);
  /* and clear the display */
  lc.clearDisplay(0);
}

/*
 This method will display the characters for the
 word "Arduino" one after the other on the matrix. 
 (you need at least 5x7 leds to see the whole chars)
 */
void writeArduinoOnMatrix() {
  /* here is the data for the characters */
  byte a[5]={B01111110,B10001000,B10001000,B10001000,B01111110};
  byte r[5]={B00010000,B00100000,B00100000,B00010000,B00111110};
  byte d[5]={B11111110,B00010010,B00100010,B00100010,B00011100};
  byte u[5]={B00111110,B00000100,B00000010,B00000010,B00111100};
  byte i[5]={B00000000,B00000010,B10111110,B00100010,B00000000};
  byte n[5]={B00011110,B00100000,B00100000,B00010000,B00111110};
  byte o[5]={B00011100,B00100010,B00100010,B00100010,B00011100};

  /* now display them one by one with a small delay */
  lc.setRow(0,0,a[0]);
  lc.setRow(0,1,a[1]);
  lc.setRow(0,2,a[2]);
  lc.setRow(0,3,a[3]);
  lc.setRow(0,4,a[4]);
  delay(delaytime1);
  lc.setRow(0,0,r[0]);
  lc.setRow(0,1,r[1]);
  lc.setRow(0,2,r[2]);
  lc.setRow(0,3,r[3]);
  lc.setRow(0,4,r[4]);
  delay(delaytime1);
  lc.setRow(0,0,d[0]);
  lc.setRow(0,1,d[1]);
  lc.setRow(0,2,d[2]);
  lc.setRow(0,3,d[3]);
  lc.setRow(0,4,d[4]);
  delay(delaytime1);
  lc.setRow(0,0,u[0]);
  lc.setRow(0,1,u[1]);
  lc.setRow(0,2,u[2]);
  lc.setRow(0,3,u[3]);
  lc.setRow(0,4,u[4]);
  delay(delaytime1);
  lc.setRow(0,0,i[0]);
  lc.setRow(0,1,i[1]);
  lc.setRow(0,2,i[2]);
  lc.setRow(0,3,i[3]);
  lc.setRow(0,4,i[4]);
  delay(delaytime1);
  lc.setRow(0,0,n[0]);
  lc.setRow(0,1,n[1]);
  lc.setRow(0,2,n[2]);
  lc.setRow(0,3,n[3]);
  lc.setRow(0,4,n[4]);
  delay(delaytime1);
  lc.setRow(0,0,o[0]);
  lc.setRow(0,1,o[1]);
  lc.setRow(0,2,o[2]);
  lc.setRow(0,3,o[3]);
  lc.setRow(0,4,o[4]);
  delay(delaytime1);
  lc.setRow(0,0,0);
  lc.setRow(0,1,0);
  lc.setRow(0,2,0);
  lc.setRow(0,3,0);
  lc.setRow(0,4,0);
  delay(delaytime1);
}

/*
  This function lights up a some Leds in a row.
 The pattern will be repeated on every row.
 The pattern will blink along with the row-number.
 row number 4 (index==3) will blink 4 times etc.
 */
void rows() {
  for(int row=0;row<8;row++) {
    delay(delaytime2);
    lc.setRow(0,row,B10100000);
    delay(delaytime2);
    lc.setRow(0,row,(byte)0);
    for(int i=0;i<row;i++) {
      delay(delaytime2);
      lc.setRow(0,row,B10100000);
      delay(delaytime2);
      lc.setRow(0,row,(byte)0);
    }
  }
}

/*
  This function lights up a some Leds in a column.
 The pattern will be repeated on every column.
 The pattern will blink along with the column-number.
 column number 4 (index==3) will blink 4 times etc.
 */
void columns() {
  for(int col=0;col<8;col++) {
    delay(delaytime2);
    lc.setColumn(0,col,B10100000);
    delay(delaytime2);
    lc.setColumn(0,col,(byte)0);
    for(int i=0;i<col;i++) {
      delay(delaytime2);
      lc.setColumn(0,col,B10100000);
      delay(delaytime2);
      lc.setColumn(0,col,(byte)0);
    }
  }
}

/* 
 This function will light up every Led on the matrix.
 The led will blink along with the row-number.
 row number 4 (index==3) will blink 4 times etc.
 */
void single() {
  for(int row=0;row<8;row++) {
    for(int col=0;col<8;col++) {
      delay(delaytime2);
      lc.setLed(0,row,col,true);
      delay(delaytime2);
      for(int i=0;i<col;i++) {
        lc.setLed(0,row,col,false);
        delay(delaytime2);
        lc.setLed(0,row,col,true);
        delay(delaytime2);
      }
    }
  }
}

void loop() { 
  writeArduinoOnMatrix();
  rows();
  columns();
  single();
}

4. Connect your Arduino to your laptop using a USB-C cable and upload the code to the arduino.

5. Test!

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11. IR Receiver Module	13. GY-521 Module