TUTORIAL
Scrolling text using some MAX7219 LED Dot Matrix displays
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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.
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.
i need a Max 7219 dot matrics having 48*8 How much it will cost
can I use arduino Leonardo instead of arduino uno in this code .
Yes the code will work without any modifications on the Leonardo as well.
Good luck with your project!
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”
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🙏
which Arduino board did u used for this project. Arduino leonardo or uno.
Can you guide me how to scroll text from top to bottom and from Left To Right?
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.
Olá, como faço para rolar texto na vertical? Obrigado….
how I turn 90 degrees writing, please help
Hi,how to use max7219 ic station this library
THIS IS FANTASTIC, SIR PLEASE TELL ME HOW TO MODIFY THIS MAX MATRIX LIBRARY FOR MORE THAN TWO MODULES. THANK YOU!
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!