Tutorial 8×8 Dot Matrix MAX7219 with Arduino UNO + Pong Game

The dot matrix that we’re going to use in this guide is a 8×8 matrix which means that it has 8 columns and 8 rows, so it contains a total of 64 LEDs.

The MAX7219 chip makes it easier to control the dot matrix, by just using 3 digital pins of the Arduino board.

I think the best option is to buy the dot matrix with the MAX7219 chip as a module, it will simplify the wiring. You can get this module on ebay for less than 2$.

dotmatrixphoto

You can control more than one matrix at a time. For that you just need to connect them to each other, as they have pins in both sides to extend the dot matrix.

Parts required

For this guide you’ll need:

1x 8×8 Dot Matrix with MAX7219 (view on eBay)
1x Arduino (view on eBay)
1x 1k ohm Potentiometer
Jumper wires

Pin Wiring

You only need to connect 5 pins from the dot matrix to your Arduino board. The wiring is pretty straightforward:

Dot matrix pin	Wiring to Arduino Uno
GND	GND
VCC	5V
DIN	Digital pin
CS	Digital pin
CLK	Digital pin

How to control the dot matrix with Arduino

For making it easier to control the dot matrix, you need to download and install in your Arduino IDE the LedControl library. To install the library follow these steps:

Click here to download the LedControl library. You should have a .zip folder in your Downloads
Unzip the .zip folder and you should get LedControl-master folder
Rename your folder from ~~LedControl-master~~ to LedControl
Move the LedControl folder to your Arduino IDE installation libraries folder
Finally, re-open your Arduino IDE

Using the LedControl library functions

The easiest way to display something on the dot matrix is by using the functions setLed(), setRow() or setColumn(). These functions allow you to control one single led, one row or one column at a time.

Here’s the parameters for each function:

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setLed(addr, row, col, state)

addr is the address of your matrix, for example, if you have just 1 matrix, the int addr will be zero.
row is the row where the led is located
col is the column where the led is located
state
- It’s true or 1 if you want to turn the led on
- It’s false or 0 if you want to switch it off

setRow(addr, row, value)

setCol(addr, column, value)

Index

As previously stated, this matrix has 8 columns and 8 rows. Each one is indexed from 0 to 7. Here’s a figure for better understanding:

index

If you want to display something in the matrix, you just need to know if in a determined row or column, the LEDs that are on or off.

For example, if you want to display a happy face, here’s what you need to do:

faces

Code

Here’s a simple sketch that displays three types of faces: a sad face, a neutral face and a happy face. Upload the following code to your board:

        
        /*
 Created by Rui Santos
 
 All the resources for this project:
 http://randomnerdtutorials.com/
*/

#include "LedControl.h"
#include "binary.h"

/*
 DIN connects to pin 12
 CLK connects to pin 11
 CS connects to pin 10 
*/
LedControl lc=LedControl(12,11,10,1);

// delay time between faces
unsigned long delaytime=1000;

// happy face
byte hf[8]= {B00111100,B01000010,B10100101,B10000001,B10100101,B10011001,B01000010,B00111100};
// neutral face
byte nf[8]={B00111100, B01000010,B10100101,B10000001,B10111101,B10000001,B01000010,B00111100};
// sad face
byte sf[8]= {B00111100,B01000010,B10100101,B10000001,B10011001,B10100101,B01000010,B00111100};

void setup() {
  lc.shutdown(0,false);
  // Set brightness to a medium value
  lc.setIntensity(0,8);
  // Clear the display
  lc.clearDisplay(0);  
}

void drawFaces(){
  // Display sad face
  lc.setRow(0,0,sf[0]);
  lc.setRow(0,1,sf[1]);
  lc.setRow(0,2,sf[2]);
  lc.setRow(0,3,sf[3]);
  lc.setRow(0,4,sf[4]);
  lc.setRow(0,5,sf[5]);
  lc.setRow(0,6,sf[6]);
  lc.setRow(0,7,sf[7]);
  delay(delaytime);
  
  // Display neutral face
  lc.setRow(0,0,nf[0]);
  lc.setRow(0,1,nf[1]);
  lc.setRow(0,2,nf[2]);
  lc.setRow(0,3,nf[3]);
  lc.setRow(0,4,nf[4]);
  lc.setRow(0,5,nf[5]);
  lc.setRow(0,6,nf[6]);
  lc.setRow(0,7,nf[7]);
  delay(delaytime);
  
  // Display happy face
  lc.setRow(0,0,hf[0]);
  lc.setRow(0,1,hf[1]);
  lc.setRow(0,2,hf[2]);
  lc.setRow(0,3,hf[3]);
  lc.setRow(0,4,hf[4]);
  lc.setRow(0,5,hf[5]);
  lc.setRow(0,6,hf[6]);
  lc.setRow(0,7,hf[7]);
  delay(delaytime);
}

void loop(){
  drawFaces();
}
        
    

        
        view raw
        
            Projects/dot_matrix_faces.ino
            
    

In the end, you’ll have something like this:

gif_face_final

Pong Game

The pong game that you’re about to try was created by Alessandro Pasotti.

For the pong game, you just need to add a 1k ohm potentiometer to the previous schematic. Assemble the new circuit as shown below:

pongping_bb

Code

Then, upload the following code to your Arduino board:

        
        /*  
 *   Play pong on an 8x8 matrix - project from itopen.it
 */
 
#include "LedControl.h"
#include "Timer.h"
 
#define POTPIN A5 // Potentiometer
#define PADSIZE 3
#define BALL_DELAY 200
#define GAME_DELAY 10
#define BOUNCE_VERTICAL 1
#define BOUNCE_HORIZONTAL -1
#define NEW_GAME_ANIMATION_SPEED 50
#define HIT_NONE 0
#define HIT_CENTER 1
#define HIT_LEFT 2
#define HIT_RIGHT 3
 
//#define DEBUG 1
 
byte sad[] = {
B00000000,
B01000100,
B00010000,
B00010000,
B00000000,
B00111000,
B01000100,
B00000000
};
 
byte smile[] = {
B00000000,
B01000100,
B00010000,
B00010000,
B00010000,
B01000100,
B00111000,
B00000000
};
 
Timer timer;
 
LedControl lc = LedControl(12,11,10,1);
 
byte direction; // Wind rose, 0 is north
int xball;
int yball;
int yball_prev;
byte xpad;
int ball_timer;
 
void setSprite(byte *sprite){
    for(int r = 0; r < 8; r++){
        lc.setRow(0, r, sprite[r]);
    }
}
 
void newGame() {
    lc.clearDisplay(0);
    // initial position
    xball = random(1, 7);
    yball = 1;
    direction = random(3, 6); // Go south
    for(int r = 0; r < 8; r++){
        for(int c = 0; c < 8; c++){
            lc.setLed(0, r, c, HIGH);
            delay(NEW_GAME_ANIMATION_SPEED);
        }
    }
    setSprite(smile);
    delay(1500);
    lc.clearDisplay(0);
}
 
void setPad() {
    xpad = map(analogRead(POTPIN), 0, 1020, 8 - PADSIZE, 0);
}
 
void debug(const char* desc){
#ifdef DEBUG
    Serial.print(desc);
    Serial.print(" XY: ");
    Serial.print(xball);
    Serial.print(", ");
    Serial.print(yball);
    Serial.print(" XPAD: ");
    Serial.print(xpad);
    Serial.print(" DIR: ");
    Serial.println(direction);
#endif
}
 
int checkBounce() {
    if(!xball || !yball || xball == 7 || yball == 6){
        int bounce = (yball == 0 || yball == 6) ? BOUNCE_HORIZONTAL : BOUNCE_VERTICAL;
#ifdef DEBUG
        debug(bounce == BOUNCE_HORIZONTAL ? "HORIZONTAL" : "VERTICAL");
#endif
        return bounce;
    }      	            