Scroll text using MAX7219 LED Dot Matrix

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OVERVIEW

We have used the MAX7219 LED Dot Matrix module in another tutorial to animate some alien invaders, now let’s scroll some text using a different library. 

In this tutorial we will connect 2 of them together and scroll the text across.

Since these modules use the MAX7219 LED driver chip, we will be able to turn on and off the 64 LEDs of each modules, using only 3 pins on our Arduino.



SCHEMATIC

Max7219 dot matrix and arduino

We are using a small breadboard to put the modules side by side to give a better experience.

As you can see, even if we are using 2 Modules, the number of pins needed, does not increase.

 

VCC and Ground are connected to the Arduino.

Pin 8 is connected to DIN, Pin 9 is connected to CS and Pin 10 is connected to CLK.

 

We then daisy-chain the modules together.



THE CODE

Our Sketch will make use of the “Maxmatrix” Library to communicate with the MAX7219 modules. 

Download and extract it to your Library folder, then restart your IDE software. 

Since we are defining all the characters possible (0-9 a-z etc..), instead of using the SRAM (2048 bytes), we will put that information in Flash memory on our UNO since that information will not change and also there’s more Flash memory available (32k).

We do this by using the “#include <avr/pgmspace.h>” and then “PROGMEM prog_uchar CH[] =” to put our array information in Flash memory.

 

Note: Flash (PROGMEM) memory can only be populated when we upload the code to our UNO. You can’t change the values in the flash after the program has started running, unlike SRAM where our sketch is run.

 

As always you can have a look at the tutorial video for more information.

#include "MaxMatrix.h"
#include "avr/pgmspace.h"


PROGMEM const unsigned char CH[] = {
3, 8, B00000000, B00000000, B00000000, B00000000, B00000000, // space
1, 8, B01011111, B00000000, B00000000, B00000000, B00000000, // !
3, 8, B00000011, B00000000, B00000011, B00000000, B00000000, // "
5, 8, B00010100, B00111110, B00010100, B00111110, B00010100, // #
4, 8, B00100100, B01101010, B00101011, B00010010, B00000000, // $
5, 8, B01100011, B00010011, B00001000, B01100100, B01100011, // %
5, 8, B00110110, B01001001, B01010110, B00100000, B01010000, // &
1, 8, B00000011, B00000000, B00000000, B00000000, B00000000, // '
3, 8, B00011100, B00100010, B01000001, B00000000, B00000000, // (
3, 8, B01000001, B00100010, B00011100, B00000000, B00000000, // )
5, 8, B00101000, B00011000, B00001110, B00011000, B00101000, // *
5, 8, B00001000, B00001000, B00111110, B00001000, B00001000, // +
2, 8, B10110000, B01110000, B00000000, B00000000, B00000000, // ,
4, 8, B00001000, B00001000, B00001000, B00001000, B00000000, // -
2, 8, B01100000, B01100000, B00000000, B00000000, B00000000, // .
4, 8, B01100000, B00011000, B00000110, B00000001, B00000000, // /
4, 8, B00111110, B01000001, B01000001, B00111110, B00000000, // 0
3, 8, B01000010, B01111111, B01000000, B00000000, B00000000, // 1
4, 8, B01100010, B01010001, B01001001, B01000110, B00000000, // 2
4, 8, B00100010, B01000001, B01001001, B00110110, B00000000, // 3
4, 8, B00011000, B00010100, B00010010, B01111111, B00000000, // 4
4, 8, B00100111, B01000101, B01000101, B00111001, B00000000, // 5
4, 8, B00111110, B01001001, B01001001, B00110000, B00000000, // 6
4, 8, B01100001, B00010001, B00001001, B00000111, B00000000, // 7
4, 8, B00110110, B01001001, B01001001, B00110110, B00000000, // 8
4, 8, B00000110, B01001001, B01001001, B00111110, B00000000, // 9
2, 8, B01010000, B00000000, B00000000, B00000000, B00000000, // :
2, 8, B10000000, B01010000, B00000000, B00000000, B00000000, // ;
3, 8, B00010000, B00101000, B01000100, B00000000, B00000000, // <
3, 8, B00010100, B00010100, B00010100, B00000000, B00000000, // =
3, 8, B01000100, B00101000, B00010000, B00000000, B00000000, // >
4, 8, B00000010, B01011001, B00001001, B00000110, B00000000, // ?
5, 8, B00111110, B01001001, B01010101, B01011101, B00001110, // @
4, 8, B01111110, B00010001, B00010001, B01111110, B00000000, // A
4, 8, B01111111, B01001001, B01001001, B00110110, B00000000, // B
4, 8, B00111110, B01000001, B01000001, B00100010, B00000000, // C
4, 8, B01111111, B01000001, B01000001, B00111110, B00000000, // D
4, 8, B01111111, B01001001, B01001001, B01000001, B00000000, // E
4, 8, B01111111, B00001001, B00001001, B00000001, B00000000, // F
4, 8, B00111110, B01000001, B01001001, B01111010, B00000000, // G
4, 8, B01111111, B00001000, B00001000, B01111111, B00000000, // H
3, 8, B01000001, B01111111, B01000001, B00000000, B00000000, // I
4, 8, B00110000, B01000000, B01000001, B00111111, B00000000, // J
4, 8, B01111111, B00001000, B00010100, B01100011, B00000000, // K
4, 8, B01111111, B01000000, B01000000, B01000000, B00000000, // L
5, 8, B01111111, B00000010, B00001100, B00000010, B01111111, // M
5, 8, B01111111, B00000100, B00001000, B00010000, B01111111, // N
4, 8, B00111110, B01000001, B01000001, B00111110, B00000000, // O
4, 8, B01111111, B00001001, B00001001, B00000110, B00000000, // P
4, 8, B00111110, B01000001, B01000001, B10111110, B00000000, // Q
4, 8, B01111111, B00001001, B00001001, B01110110, B00000000, // R
4, 8, B01000110, B01001001, B01001001, B00110010, B00000000, // S
5, 8, B00000001, B00000001, B01111111, B00000001, B00000001, // T
4, 8, B00111111, B01000000, B01000000, B00111111, B00000000, // U
5, 8, B00001111, B00110000, B01000000, B00110000, B00001111, // V
5, 8, B00111111, B01000000, B00111000, B01000000, B00111111, // W
5, 8, B01100011, B00010100, B00001000, B00010100, B01100011, // X
5, 8, B00000111, B00001000, B01110000, B00001000, B00000111, // Y
4, 8, B01100001, B01010001, B01001001, B01000111, B00000000, // Z
2, 8, B01111111, B01000001, B00000000, B00000000, B00000000, // [
4, 8, B00000001, B00000110, B00011000, B01100000, B00000000, // \ backslash
2, 8, B01000001, B01111111, B00000000, B00000000, B00000000, // ]
3, 8, B00000010, B00000001, B00000010, B00000000, B00000000, // hat
4, 8, B01000000, B01000000, B01000000, B01000000, B00000000, // _
2, 8, B00000001, B00000010, B00000000, B00000000, B00000000, // `
4, 8, B00100000, B01010100, B01010100, B01111000, B00000000, // a
4, 8, B01111111, B01000100, B01000100, B00111000, B00000000, // b
4, 8, B00111000, B01000100, B01000100, B00101000, B00000000, // c
4, 8, B00111000, B01000100, B01000100, B01111111, B00000000, // d
4, 8, B00111000, B01010100, B01010100, B00011000, B00000000, // e
3, 8, B00000100, B01111110, B00000101, B00000000, B00000000, // f
4, 8, B10011000, B10100100, B10100100, B01111000, B00000000, // g
4, 8, B01111111, B00000100, B00000100, B01111000, B00000000, // h
3, 8, B01000100, B01111101, B01000000, B00000000, B00000000, // i
4, 8, B01000000, B10000000, B10000100, B01111101, B00000000, // j
4, 8, B01111111, B00010000, B00101000, B01000100, B00000000, // k
3, 8, B01000001, B01111111, B01000000, B00000000, B00000000, // l
5, 8, B01111100, B00000100, B01111100, B00000100, B01111000, // m
4, 8, B01111100, B00000100, B00000100, B01111000, B00000000, // n
4, 8, B00111000, B01000100, B01000100, B00111000, B00000000, // o
4, 8, B11111100, B00100100, B00100100, B00011000, B00000000, // p
4, 8, B00011000, B00100100, B00100100, B11111100, B00000000, // q
4, 8, B01111100, B00001000, B00000100, B00000100, B00000000, // r
4, 8, B01001000, B01010100, B01010100, B00100100, B00000000, // s
3, 8, B00000100, B00111111, B01000100, B00000000, B00000000, // t
4, 8, B00111100, B01000000, B01000000, B01111100, B00000000, // u
5, 8, B00011100, B00100000, B01000000, B00100000, B00011100, // v
5, 8, B00111100, B01000000, B00111100, B01000000, B00111100, // w
5, 8, B01000100, B00101000, B00010000, B00101000, B01000100, // x
4, 8, B10011100, B10100000, B10100000, B01111100, B00000000, // y
3, 8, B01100100, B01010100, B01001100, B00000000, B00000000, // z
3, 8, B00001000, B00110110, B01000001, B00000000, B00000000, // {
1, 8, B01111111, B00000000, B00000000, B00000000, B00000000, // |
3, 8, B01000001, B00110110, B00001000, B00000000, B00000000, // }
4, 8, B00001000, B00000100, B00001000, B00000100, B00000000, // ~
};

int data = 8;    // DIN pin of MAX7219 module
int load = 9;    // CS pin of MAX7219 module
int clock = 10;  // CLK pin of MAX7219 module

int maxInUse = 2;  //how many MAX7219 are connected

MaxMatrix m(data, load, clock, maxInUse); // define Library

byte buffer[10];

char string1[] = " Brainy-Bits.com      ";  // Scrolling Text


void setup(){
  m.init(); // module MAX7219
  m.setIntensity(5); // LED Intensity 0-15
}

void loop(){
  
  byte c;
  delay(100);
  m.shiftLeft(false, true);
  printStringWithShift(string1, 100);  // Send scrolling Text

}

// Put extracted character on Display
void printCharWithShift(char c, int shift_speed){
  if (c < 32) return;
  c -= 32;
  memcpy_P(buffer, CH + 7*c, 7);
  m.writeSprite(maxInUse*8, 0, buffer);
  m.setColumn(maxInUse*8 + buffer[0], 0);
  
  for (int i = 0; i < buffer[0]+1; i++) 
  {
    delay(shift_speed);
    m.shiftLeft(false, false);
  }
}

// Extract characters from Scrolling text
void printStringWithShift(char* s, int shift_speed){
  while (*s != 0){
    printCharWithShift(*s, shift_speed);
    s++;
  }
}


TUTORIAL VIDEO



DOWNLOAD

Copy and paste the above code in the Arduino IDE to program your Arduino.

 

Used Libraries:

Download the MaxMatrix library here:  https://github.com/riyas-org/max7219/tree/master/MaxMatrix

 

Once downloaded, just extract the content of the zip files inside your “arduino/libraries” folder.

12 Comments

JMR - Jan 30, 2017

Hello,
I have an issue concerning the orientation of letter on the Dot matrix.
Have you got a solution.
I can send you a picture if it’s necessary…
Thanks
JMR

bagus - Jan 30, 2017

why when I verify the troubled program on PROGMEM prog_char CH [] =
The program is not a program type. can you help me

Brainy-Bits - Jan 30, 2017

Bagus:
When we did this tutorial we were using the 1.0.5 version of the Arduino IDE. It seems that if you’re using a newer version of the IDE Software you need to replace ‘prog_uchar’ with ‘const unsigned char’ in the tutorial sketch to not get an error when compiling. I’ve gone ahead and updated the sketch above, so you can just copy and paste it if you want.

SD Solar - Jan 30, 2017

I have the same kind of individual displays as shown in this demo, and the code won’t work. I installed each with the chip at the bottom. The first one is very bright but the rest are much more dim.

Plus, I have the other kind where there are 4 in a row. On those, this code moves the characters sideways across the 4, and they are of equal brightness.

It would be handy to know how to rotate the orientation so it would also work on the 4-in-a-row displays.

Can you point me to a link which can accomplish scrolling lengthwise along the 4?

ANAS - Jan 30, 2017

Sir, I faces a problem regarding this project.
My message moves vertically on each cascaded MAX7219 module. I also uploaded your attached arduino code but still message moves vertical. So, please kindly give the solution of this problem.

Jerold - Jan 30, 2017

Sir, My message moves vertically what part of the code that i can change to move in horizontally?

Dhiraj - Jan 30, 2017

message moves vertically pls help to move in horizontally?

dbuilder81 - Jan 30, 2017

My display was wired oriented 90 degrees, how do I fix this problem? My text scrolls up instead of left

Muhammad Sameer - Jan 30, 2017

Thanks brother, finally your idea worked after 5 hours struggle. AlhamdulillAh

Paul - Jan 30, 2017

What should I do to move it horizontally?

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