Scrolling text using the MAX7219 LED Dot Matrix

TUTORIAL

Scrolling text using some MAX7219 LED Dot Matrix displays
–

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.

CONNECTIONS

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.

14 Comments

azhar August 22, 2019 at 9:09 am - Reply

i need a Max 7219 dot matrics having 48*8 How much it will cost
gurmajor singh July 20, 2019 at 4:54 pm - Reply

can I use arduino Leonardo instead of arduino uno in this code .
- brainy-bits July 20, 2019 at 4:57 pm - Reply
  
  Yes the code will work without any modifications on the Leonardo as well.
  
  Good luck with your project!
Tim January 2, 2019 at 8:41 pm - Reply

Can you freeze or stop the scrolling text if desired? I was thinking of using this in a game. The text would need to do the following:

1) Scrolling “Three, Two, One…..Go!”

2) Fixed display, counting downward – “30”, “29”, “28”, etc.

3) Scrolling “You win!” or “You lose”
Joshi Girish V. November 6, 2018 at 5:44 am - Reply

Dear Sir,
Your code is working properly but when I use one combined module of 04 Dot Matrix Units at that time, Text is scrolling symultaneously from left to right by keeping a gap of one character on each display unit. Therefore, I am not getting the effect as I got the same by using 04 seperste Dot Matrix Modules. All characters of the text are scrolling from left to right vertically and due to combined fixed module, I am unable to change the position of any display unit.

Please suggest me what to do when display units are arranged vertically instead of horizontally as required.

🙏Thanks🙏
- brainy-bits November 7, 2018 at 8:36 pm - Reply
  
  Check out this new tutorial: https://www.brainy-bits.com/arduino-max7219-scrolling-text-matrix/
- gurmajor singh July 20, 2019 at 4:56 pm - Reply
  
  which Arduino board did u used for this project. Arduino leonardo or uno.
Girish Joshi November 6, 2018 at 4:34 am - Reply

Can you guide me how to scroll text from top to bottom and from Left To Right?
Joshi Girish V. October 26, 2018 at 3:12 pm - Reply

Very Nice & Excellent Job Sir.

Can you give me some idea for constructing the same circuit by using 8×8 RGB LED Dot Matrix Units & Modules.

Thanks.
Have A Fabulous Life.
Ozéias April 18, 2018 at 7:21 am - Reply

Olá, como faço para rolar texto na vertical? Obrigado….
Ady April 14, 2018 at 2:38 am - Reply

how I turn 90 degrees writing, please help
Ady April 14, 2018 at 2:36 am - Reply

Hi,how to use max7219 ic station this library
ASHAR FAROOQ February 28, 2018 at 2:13 pm - Reply

THIS IS FANTASTIC, SIR PLEASE TELL ME HOW TO MODIFY THIS MAX MATRIX LIBRARY FOR MORE THAN TWO MODULES. THANK YOU!
- brainy-bits March 1, 2018 at 9:34 pm - Reply
  
  Find this line in the code:
  
  int maxInUse = 2; //how many MAX7219 are connected
  
  And enter the number of modules you want (instead of 2 enter another number)
  
  Hope that helps!