Reading and Writing 8 Digit Numbers on Max7219 With Arduino

December 12, 2021 Post a Comment

In this tutorial, you will learn how to control a MAX7219 LED dot matrix display with Arduino. I have included a wiring diagram and many example codes! The code in this tutorial can be used for 8×8, 8×32, and even larger displays.

For this tutorial, I will be using the MD_Parola in combination with the MD_MAX72XX Arduino library. These libraries make displaying scrolling text and other animations super easy. In the first part of this article, I will cover the basics of printing text on the display. Next, we will look at scrolling text and other text animations. Lastly, I will show you how to use text sprites.

PCBWay

If you would like to learn more about other types of displays, check out the articles below:

Supplies

Hardware components

generic-MAX7219-8x8-LED-dot-matrix-display

Software

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About the MAX7219 LED driver

The MAX7219 LED driver can be used to control 7-segment displays up to 8 digits, bar-graph displays, or 64 individual LEDs. The driver communicates with the Arduino through SPI so you only need three wires to control the display.

Since the MAX7219 can control a maximum of 64 LEDs, the maximum size dot matrix display it can drive is 8×8 pixels. However, you can daisy chain multiple drivers and matrices together and easily control much larger displays like 8×32, 8×64, or even bigger. Still, you only need three wires to control all of the ICs so you need very few I/O pins of the Arduino.

Below you can find the specifications of a typical MAX7219 8×32 LED dot matrix display.

MAX7219 LED dot matrix display specifications

Operating voltage	5 V
Display driver	MAX7219 x 4
Brightness levels	16
Display dimensions	32 x 128 x 15 mm
Pixels	8×32, ⌀ 3 mm
Cost	Check price

For more information, you can check out the datasheet:

Almost all of the displays I have used in the past used a 1088AS type 8×8 LED matrix. You can find a datasheet from one of the companies that makes them below:

How to connect the dot matrix display to the Arduino

The MAX7219 LED display driver communicates with the Arduino through SPI (Serial Peripheral Interface). To learn more about this data protocol, please see this page on the Arduino website.

With an SPI interface there is always one master device (the Arduino) that controls the peripheral devices (also known as slaves). You can control the display either through the Arduino's AVR microcontroller hardware SPI interface or three arbitrary digital pins (software SPI).

The hardware SPI pins (MOSI, MISO, and SCK) are at a specific location on each Arduino board. This interface is faster than using software SPI, but you will need to use the following fixed output pins:

Hardware SPI pin locations

Board	MOSI	MISO	SCK	Level
Arduino Uno	11 or ICSP-4	12 or ICSP-1	13 or ICSP-3	5 V
Arduino Mega	51 or ICSP-4	50 or ICSP-1	52 or ICSP-3	5 V
Arduino Leonardo	ICSP-4	ICSP-1	ICSP-3	5 V
Arduino Due	SPI-4	SPI1	SPI-3	3.3 V
Arduino MKR1000	8	10	9	3.3 V

Hardware SPI pin locations on different Arduino boards.

Note that the MOSI, MISO, and SCK pins are also at a consistent physical location on the 6-pin ICSP header:

To control MAX7219 displays you only need to make three connections:

MOSI (Master Out Slave In) connected to DIN – The Master line sending data to the peripherals.
SCK (Serial Clock) connected to CLK – The clock pulses which synchronize data transmission generated by the master.
SS (Slave Select) connected to CS – The pin on each device that the master can use to enable and disable specific devices.

You can daisy chain multiple displays to create one large display by connecting DOUT of the first display to DIN of the next display. VCC, GND, CLK, and CS are shared between all of the displays.

You can select any of the digital pins of the Arduino for the SS/CS pin. Note that for this tutorial I used pin 3 (see table below).

The wiring diagram below shows you how to connect the MAX7219 LED dot matrix display to the Arduino. Note that when using the MD_Parola library, you need to orient the display with the DIN connector on the right, otherwise the text will be printed upside down. For more information see the section below.

MAX7219-LED-dot-matrix-display-with-Arduino-Uno-wiring-diagram-schematic-pinout — MAX7219 LED dot matrix display with Arduino wiring diagram

The connections are also given in the table below:

MAX7219 LED dot matrix display connections

MAX7219 Display	Arduino
VCC	5 V
GND	GND
DIN	11 (MOSI)
CS	3 (SS)
CLK	13 (SCK)

If you want to use software SPI instead, you can connect DIN, CS, and CLK to any of the digital pins of the Arduino. You just need to specify the pin numbers in the setup of the Arduino code (see examples below).

Power requirements

The maximum power that the Arduino Uno can safely deliver when powered from USB is around 400 mA at 5 V. If you want to control a large display it is therefore advised to use an external power supply.

Installing the MD_Parola and MD_MAX72XX Arduino libraries

To control the MAX7219 display we will be using two awesome Arduino libraries created by Marco Colli from MajicDesigns. The MD_Parola library can be used to create many different text animations like scrolling and sprite text effects. This library depends on the MD_MAX72XX library which implements the hardware functions of the LED matrix.

This are some functions and features of the library:

Left, right, or center text justification
Text scrolling with entry and exit effects
Control display parameters and animation speed
Multiple virtual displays (zones) in each string of LED modules
Support for hardware SPI interface
User-defined fonts and/or individual characters substitutions
Support for double-height displays
Support for mixing text and graphics on the same display

Marco has been working on this library for several years and has written some excellent tutorials on his blog. The source code and documentation for the libraries can be found here:

MD_Parola source code on GitHub
MD_Parola documentation
MD_MAX72XX source code on GitHub
MD_MAX72XX documentation

You can install the libraries via the Library Manager of the Arduino IDE. Go to Tools > Manage Libraries… or type Ctrl + Shift + I on Windows. The Library Manager will open and update the list of installed libraries.

Installing an Arduino library step 1 open Library Manager

Search for 'MD_MAX72XX' and look for the libraries by majicDesigns. Select the latest version and then click install. Make sure that you install both the MD_MAX72XX library and the MD_Parola library.

Installing an Arduino library step 2 MD_Parola and MD_MAX72XX

Different types of LED dot matrix displays

Many different types and sizes of MAX7219 LED dot matrix displays are available on the market. The MD_MAX72XX library supports almost all of these displays but you need to configure the library correctly for the type of matrix being used.

Below you can find information about connecting and configuring the most common MAX7219 LED dot matrix displays that you can buy on Amazon, AliExpress, and eBay.

FC-16 8×8 or 8×32 module

This is probably the most common MAX7219 display that you can find. It typically comes as either an 8×8 or 8×32 LED matrix and you can buy them with different colors of LEDs.

Module orientation and connections

You can easily connect multiple 8×8 or 8×32 modules together to create one larger display. I typically solder straight male headers on the back of the modules and connect them together using jumpers. This way you can take them apart without having to desolder any connections.

The display is oriented with the DIN side on the right. Note that the screen-printed text on the back of the PCB might be upside down in this orientation.

          DP A  B  C  D  E  F  G           +------------------------+           | 7  6  5  4  3  2  1  0 | D0   CLK <---|                      1 | D1 <--- CLK    CS <---|                      2 | D2 <--- CS  DOUT <---|                      3 | D3 <--- DIN   GND ----|                   O  4 | D4 ---- GND   VCC ----|                O  O  5 | D5 ---- VCC           |             O  O  O  6 | D6           |          O  O  O  O  7 | D7           +------------------------+

Hardware configuration in Arduino code

When setting up the display in your Arduino code you need to set the HARDWARE_TYPE to FC16_HW and specify the number of devices you have connected. An 8×8 matrix counts as 1 device, so if you want to control an 8×32 module you need to set MAX_DEVICES to 4 (an 8×32 display contains 4 MAX7219 ICs).

// Hardware SPI: #define HARDWARE_TYPE MD_MAX72XX::FC16_HW #define MAX_DEVICES 4 #define CS_PIN 2  // Create a new instance of the MD_MAX72XX class: MD_Parola matrix = MD_Parola(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);  // For software SPI you also need to specify the DATA_PIN and the CLK_PIN connections: // #define DATA_PIN 3 // #define CLK_PIN 4  // Create a new instance of the MD_MAX72XX class: // MD_Parola matrix = MD_Parola(HARDWARE_TYPE, DATA_PIN, CLK_PIN, CS_PIN, MAX_DEVICES);

Generic 8×8 module

This is an 8×8 module mounted on a green PCB with the MAX7219 IC below the LED matrix. They are characterized by the 5-pin connectors at the short ends of the rectangular PCB.

Module orientation and connections

The generic module needs to be oriented with the MAX7219 IC at the top. You can connect multiple modules together with some short female to female jumper wires. Simply connect all the pins of the DOUT side of the first module to the DIN side of the next module.

          C  C  D  G  V       L  S  I  N  C       K     N  D  C       |  |  |  |  |       V  V  V  |  |   D7 D6 D5 D4 D3 D2 D1 D0 +------------------------+ | 7  6  5  4  3  2  1  0 | DP |                      1 | A |                      2 | B |                      3 | C | O                    4 | D | O  O                 5 | E | O  O  O              6 | F | O  O  O  O           7 | G +------------------------+       |  |  |  |  |       V  V  V  |  |       C  C  D  G  V       L  S  O  N  C       K     U  D  C             T

Hardware configuration in Arduino code

For the generic display modules, you need to set the HARDWARE_TYPE to GENERIC_HW. The rest of the setup and MAX_DEVICES is the same as for the FC-16 modules.

// Hardware SPI: #define HARDWARE_TYPE MD_MAX72XX::GENERIC_HW #define MAX_DEVICES 1 #define CS_PIN 2  // Create a new instance of the MD_MAX72XX class: MD_Parola matrix = MD_Parola(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);  // For software SPI you also need to specify the DATA_PIN and the CLK_PIN connections: // #define DATA_PIN 3 // #define CLK_PIN 4  // Create a new instance of the MD_MAX72XX class: // MD_Parola matrix = MD_Parola(HARDWARE_TYPE, DATA_PIN, CLK_PIN, CS_PIN, MAX_DEVICES);

Arduino example codes

Below you will find several example codes that cover the basic functions of the MD_Parola Arduino library. After each example I explain how the code works so you should be able to modify it to suit your needs. You can also find more examples when you go to File > Examples > MD_Parola in the Arduino IDE, but they don't include any explanation so they might be a bit hard to follow.

Basic Arduino example code to print text

With the example code below you can print text on the display without any animations.

You can upload the example code to your Arduino via the Arduino IDE. For this tutorial, I used this standard 8x32 LED dot matrix display but you can use other types and/or sizes as well (see code explanation below).

You can copy the code by clicking on the button in the top right corner of the code field.

/* Basic example code for MAX7219 LED dot matrix display with Arduino. More info: https://www.makerguides.com */  // Include the required Arduino libraries: #include <MD_Parola.h> #include <MD_MAX72xx.h> #include <SPI.h>  // Define hardware type, size, and output pins: #define HARDWARE_TYPE MD_MAX72XX::FC16_HW #define MAX_DEVICES 4 #define CS_PIN 3  // Create a new instance of the MD_Parola class with hardware SPI connection: MD_Parola myDisplay = MD_Parola(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);  // Setup for software SPI: // #define DATAPIN 2 // #define CLK_PIN 4 // MD_Parola myDisplay = MD_Parola(HARDWARE_TYPE, DATA_PIN, CLK_PIN, CS_PIN, MAX_DEVICES);  void setup() {   // Intialize the object:   myDisplay.begin();   // Set the intensity (brightness) of the display (0-15):   myDisplay.setIntensity(0);   // Clear the display:   myDisplay.displayClear(); }  void loop() {   myDisplay.setTextAlignment(PA_CENTER);   myDisplay.print("Center");   delay(2000);   myDisplay.setTextAlignment(PA_LEFT);   myDisplay.print("Left");   delay(2000);   myDisplay.setTextAlignment(PA_RIGHT);   myDisplay.print("Right");   delay(2000);   myDisplay.setTextAlignment(PA_CENTER);   myDisplay.setInvert(true);   myDisplay.print("Invert");   delay(2000);   myDisplay.setInvert(false);   myDisplay.print(1234);   delay(2000); }

You should see the following output:

How the code works

The first step is to include all the required Arduino libraries. As I mentioned before, the MD_MAX72XX library implements the hardware functions of the LED matrix and the MD_Parola library the text effects. You will also need to include the SPI library, which comes pre-installed in the Arduino IDE. This library is used for the Serial Peripheral Interface communication between the display and the Arduino.

// Include the required Arduino libraries: #include <MD_Parola.h> #include <MD_MAX72xx.h> #include <SPI.h>

Next, we need to specify which hardware we are using. Since I used a standard 8×32 display (also known as FC-16), I set the HARDWARE_TYPE to FC16_HW. The number of MAX7219 ICs in an 8×32 display is 4 so I set MAX_DEVICES to 4. Lastly, I defined to which pin the CS pin of the display is connected (output pin 3 in this case). See the section about display types for a more detailed explanation on how to set up other types of displays.

The statement#define is used to give a name to a constant value. The compiler will replace any references to this constant with the defined value when the program is compiled. So everywhere you mentionCS_PIN, the compiler will replace it with the value 3 when the program is compiled.

// Define hardware type, size, and output pins: #define HARDWARE_TYPE MD_MAX72XX::FC16_HW #define MAX_DEVICES 4 #define CS_PIN 3

After this, a new instance of the MD_Parola class is created with the function MD_Parola(). This function needs three parameters, the first is the hardware type, the second the CS pin, and the third the number of max devices connected.

Note that I have called the MD_Parola object 'myDisplay' but you can use other names as well. You will need to change 'myDisplay' to the new name in the rest of the sketch.

When you want to use software SPI instead of hardware SPI, you also need to define the data and clock output pins and pass these as parameters when setting up the display object.

// Create a new instance of the MD_Parola class with hardware SPI connection: MD_Parola myDisplay = MD_Parola(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);  // Setup for software SPI: // #define DATAPIN 2 // #define CLK_PIN 4 // MD_Parola myDisplay = MD_Parola(HARDWARE_TYPE, DATA_PIN, CLK_PIN, CS_PIN, MAX_DEVICES);

In the setup section of the code, we first initialize the object with the function begin(). The brightness of the display can be set with the function setIntensity(). You can enter a value between 0 (minimum brightness) and 15 (maximum brightness). The display is cleared with the function displayClear().

void setup() {   // Intialize the object:   myDisplay.begin();   // Set the intensity (brightness) of the display (0-15):   myDisplay.setIntensity(0);   // Clear the display:   myDisplay.displayClear(); }

In the loop section of the code, we first set the alignment of the text to be printed with the function setTextAlignment(). You can left, center, and right align the text with PA_LEFT, PA_CENTER, and PA_RIGHT respectively.

Next, the string 'Center' is printed withmyDisplay.print("Center"). Note that you need to place quotation marks (" ") around the text since we are printing a text string. When you want to print numbers, no quotation marks are necessary. For examplemyDisplay.print(1234). You can invert the display, i.e. LEDs normally on turn off and vice versa, with myDisplay.setInvert(true).

void loop() {   myDisplay.setTextAlignment(PA_CENTER);   myDisplay.print("Center");   delay(2000);   myDisplay.setTextAlignment(PA_LEFT);   myDisplay.print("Left");   delay(2000);   myDisplay.setTextAlignment(PA_RIGHT);   myDisplay.print("Right");   delay(2000);   myDisplay.setTextAlignment(PA_CENTER);   myDisplay.setInvert(true);   myDisplay.print("Invert");   delay(2000);   myDisplay.setInvert(false);   myDisplay.print(1234);   delay(2000); }

Scrolling text Arduino example code

When you want to print a message on a dot matrix display, you will often find that the display is too small to fit the entire message. The solution is in the MD_Parola library, which makes it super easy to create scrolling text effects. In the following examples, I will show you how to set this up, as well as how to use some of the other available text effects.

You can copy the code below by clicking on the button in the top right corner of the code field.

/* Example code for scrolling text effect on MAX7219 LED dot matrix display with Arduino. More info: https://www.makerguides.com */  // Include the required Arduino libraries: #include <MD_Parola.h> #include <MD_MAX72xx.h> #include <SPI.h>  // Define hardware type, size, and output pins: #define HARDWARE_TYPE MD_MAX72XX::FC16_HW #define MAX_DEVICES 4 #define CS_PIN 3  // Create a new instance of the MD_Parola class with hardware SPI connection: MD_Parola myDisplay = MD_Parola(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);  // Setup for software SPI: // #define DATA_PIN 2 // #define CLK_PIN 4 // MD_Parola myDisplay = MD_Parola(HARDWARE_TYPE, DATA_PIN, CLK_PIN, CS_PIN, MAX_DEVICES);  void setup() {   // Intialize the object:   myDisplay.begin();   // Set the intensity (brightness) of the display (0-15):   myDisplay.setIntensity(0);   // Clear the display:   myDisplay.displayClear();   myDisplay.displayText("Scrolling text", PA_CENTER, 100, 0, PA_SCROLL_LEFT, PA_SCROLL_LEFT); }  void loop() {   if (myDisplay.displayAnimate()) {     myDisplay.displayReset();   } }

How the code works

The first part of the code up to the end of the setup section is exactly the same as in the previous example. At the end of the setup section, we specify how we want to display the text with the function displayText(pText, align, speed, pause, effectIn, effectOut). This function takes 5 arguments.

The first parameter is the text string, in this case "Scrolling text".

The second argument sets the alignment of the text during the optional pause. You can use the same alignment options as in the previous example, i.e. PA_CENTER, PA_LEFT, or PA_RIGHT.

The third and fourth arguments set the speed of the animation and pause time respectively. The speed of the display is the time in milliseconds between animation frames. The lower this time the faster the animation. If you want to pause the text in between the in and out animation, you can set the pause time in milliseconds. I set it to zero so the text scrolls continuously.

Next, the in and out effects are specified. In this case I used PA_SCROLL_LEFT for both. See the example below for other text effects.

          myDisplay.displayText("Scrolling text", PA_CENTER, 100, 0, PA_SCROLL_LEFT, PA_SCROLL_LEFT);

In the loop section, you only need two functions to create a scrolling text display.

First, we use the function displayAnimate() in an if statement. This function animates the display using the currently specified text and animation parameters and returns true when the animation has finished. When the animation has finished, we reset the display with the function displayReset() so the text is displayed in a loop.

void loop() {   if (myDisplay.displayAnimate()) {     myDisplay.displayReset();   } }

Other text effects

The library includes several other text effects that you can use:

PA_PRINT,
PA_SCAN_HORIZ,

PA_SCROLL_LEFT,
PA_WIPE,
PA_SCROLL_UP_LEFT,
PA_SCROLL_UP,
PA_OPENING_CURSOR,
PA_GROW_UP,
PA_MESH,
PA_SCROLL_UP_RIGHT,
PA_BLINDS,
PA_CLOSING,
PA_RANDOM,
PA_GROW_DOWN,
PA_SCAN_VERT,
PA_SCROLL_DOWN_LEFT,
PA_WIPE_CURSOR,
PA_DISSOLVE,
PA_OPENING,
PA_CLOSING_CURSOR,
PA_SCROLL_DOWN_RIGHT,
PA_SCROLL_RIGHT,
PA_SLICE,
PA_SCROLL_DOWN

The example code below steps through the different effect so you can see what they look like.

/* Example code for scrolling text and other text effects on MAX7219 LED dot matrix display with Arduino. More info: https://www.makerguides.com */  // Include the required Arduino libraries: #include <MD_Parola.h> #include <MD_MAX72xx.h> #include <SPI.h>  int i = 0;  textEffect_t texteffect[] = {   PA_PRINT,   PA_SCAN_HORIZ,   PA_SCROLL_LEFT,   PA_WIPE,   PA_SCROLL_UP_LEFT,   PA_SCROLL_UP,   PA_OPENING_CURSOR,   PA_GROW_UP,   PA_MESH,   PA_SCROLL_UP_RIGHT,   PA_BLINDS,   PA_CLOSING,   PA_RANDOM,   PA_GROW_DOWN,   PA_SCAN_VERT,   PA_SCROLL_DOWN_LEFT,   PA_WIPE_CURSOR,   PA_DISSOLVE,   PA_OPENING,   PA_CLOSING_CURSOR,   PA_SCROLL_DOWN_RIGHT,   PA_SCROLL_RIGHT,   PA_SLICE,   PA_SCROLL_DOWN };  // Define hardware type, size, and output pins: #define HARDWARE_TYPE MD_MAX72XX::FC16_HW #define MAX_DEVICES 4 #define CS_PIN 3  // Create a new instance of the MD_Parola class with hardware SPI connection: MD_Parola myDisplay = MD_Parola(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);  // Setup for software SPI: // #define DATA_PIN 2 // #define CLK_PIN 4 // MD_Parola myDisplay = MD_Parola(HARDWARE_TYPE, DATA_PIN, CLK_PIN, CS_PIN, MAX_DEVICES);  void setup() {   myDisplay.begin();   myDisplay.setIntensity(0);   myDisplay.setTextAlignment(PA_CENTER);   myDisplay.setPause(1000);   myDisplay.setSpeed(100);   myDisplay.displayClear(); }  void loop() {   if (myDisplay.displayAnimate()) {     if (i < sizeof(texteffect)) {       i++;     }     else {       i = 0;     }     myDisplay.displayText("Hello", myDisplay.getTextAlignment(), myDisplay.getSpeed(), myDisplay.getPause(), texteffect[i], texteffect[i]);     myDisplay.displayReset();   } }

Text sprites

A relatively new function of the MD_Parola library is animated text sprites. In computer graphics, a sprite is a two-dimensional bitmap that is integrated into a larger scene (in this case, the matrix display).

A sprite is made up of a number of frames that run sequentially to make the animation on the display. Once the animation reaches the last frame it restarts from the first frame.

Note that I used an 8×64 matrix display for this example by connecting two 8×32 displays together (MAX_DEVICES is set to 8).

/* Example code for sprite text effect on MAX7219 LED dot matrix display with Arduino. More info: https://www.makerguides.com */  // Include the required Arduino libraries: #include <MD_Parola.h> #include <MD_MAX72xx.h> #include <SPI.h>  // Define hardware type, size, and output pins: #define HARDWARE_TYPE MD_MAX72XX::FC16_HW #define MAX_DEVICES 8 #define CS_PIN 3  // Create a new instance of the MD_Parola class with hardware SPI connection: MD_Parola myDisplay = MD_Parola(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);  // Setup for software SPI: // #define DATA_PIN 2 // #define CLK_PIN 4 // MD_Parola myDisplay = MD_Parola(HARDWARE_TYPE, DATA_PIN, CLK_PIN, CS_PIN, MAX_DEVICES);  // Sprite definitions: const uint8_t F_PMAN1 = 6; const uint8_t W_PMAN1 = 8; const uint8_t PROGMEM pacman1[F_PMAN1 * W_PMAN1] =  // gobbling pacman animation {   0x00, 0x81, 0xc3, 0xe7, 0xff, 0x7e, 0x7e, 0x3c,   0x00, 0x42, 0xe7, 0xe7, 0xff, 0xff, 0x7e, 0x3c,   0x24, 0x66, 0xe7, 0xff, 0xff, 0xff, 0x7e, 0x3c,   0x3c, 0x7e, 0xff, 0xff, 0xff, 0xff, 0x7e, 0x3c,   0x24, 0x66, 0xe7, 0xff, 0xff, 0xff, 0x7e, 0x3c,   0x00, 0x42, 0xe7, 0xe7, 0xff, 0xff, 0x7e, 0x3c, };  const uint8_t F_PMAN2 = 6; const uint8_t W_PMAN2 = 18; const uint8_t PROGMEM pacman2[F_PMAN2 * W_PMAN2] =  // pacman pursued by a ghost {   0x00, 0x81, 0xc3, 0xe7, 0xff, 0x7e, 0x7e, 0x3c, 0x00, 0x00, 0x00, 0xfe, 0x7b, 0xf3, 0x7f, 0xfb, 0x73, 0xfe,   0x00, 0x42, 0xe7, 0xe7, 0xff, 0xff, 0x7e, 0x3c, 0x00, 0x00, 0x00, 0xfe, 0x7b, 0xf3, 0x7f, 0xfb, 0x73, 0xfe,   0x24, 0x66, 0xe7, 0xff, 0xff, 0xff, 0x7e, 0x3c, 0x00, 0x00, 0x00, 0xfe, 0x7b, 0xf3, 0x7f, 0xfb, 0x73, 0xfe,   0x3c, 0x7e, 0xff, 0xff, 0xff, 0xff, 0x7e, 0x3c, 0x00, 0x00, 0x00, 0xfe, 0x7b, 0xf3, 0x7f, 0xfb, 0x73, 0xfe,   0x24, 0x66, 0xe7, 0xff, 0xff, 0xff, 0x7e, 0x3c, 0x00, 0x00, 0x00, 0xfe, 0x7b, 0xf3, 0x7f, 0xfb, 0x73, 0xfe,   0x00, 0x42, 0xe7, 0xe7, 0xff, 0xff, 0x7e, 0x3c, 0x00, 0x00, 0x00, 0xfe, 0x7b, 0xf3, 0x7f, 0xfb, 0x73, 0xfe, };  const uint8_t F_WAVE = 14; const uint8_t W_WAVE = 14; const uint8_t PROGMEM wave[F_WAVE * W_WAVE] =  // triangular wave / worm {   0x08, 0x04, 0x02, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x40, 0x20, 0x10,   0x10, 0x08, 0x04, 0x02, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x40, 0x20,   0x20, 0x10, 0x08, 0x04, 0x02, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x40,   0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80,   0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40,   0x40, 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20,   0x20, 0x40, 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01, 0x02, 0x04, 0x08, 0x10,   0x10, 0x20, 0x40, 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01, 0x02, 0x04, 0x08,   0x08, 0x10, 0x20, 0x40, 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01, 0x02, 0x04,   0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01, 0x02,   0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01,   0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02,   0x02, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x40, 0x20, 0x10, 0x08, 0x04,   0x04, 0x02, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x40, 0x20, 0x10, 0x08, };  const uint8_t F_ROLL1 = 4; const uint8_t W_ROLL1 = 8; const uint8_t PROGMEM roll1[F_ROLL1 * W_ROLL1] =  // rolling square {   0xff, 0x8f, 0x8f, 0x8f, 0x81, 0x81, 0x81, 0xff,   0xff, 0xf1, 0xf1, 0xf1, 0x81, 0x81, 0x81, 0xff,   0xff, 0x81, 0x81, 0x81, 0xf1, 0xf1, 0xf1, 0xff,   0xff, 0x81, 0x81, 0x81, 0x8f, 0x8f, 0x8f, 0xff, };  const uint8_t F_ROLL2 = 4; const uint8_t W_ROLL2 = 8; const uint8_t PROGMEM roll2[F_ROLL2 * W_ROLL2] =  // rolling octagon {   0x3c, 0x4e, 0x8f, 0x8f, 0x81, 0x81, 0x42, 0x3c,   0x3c, 0x72, 0xf1, 0xf1, 0x81, 0x81, 0x42, 0x3c,   0x3c, 0x42, 0x81, 0x81, 0xf1, 0xf1, 0x72, 0x3c,   0x3c, 0x42, 0x81, 0x81, 0x8f, 0x8f, 0x4e, 0x3c, };  const uint8_t F_LINES = 3; const uint8_t W_LINES = 8; const uint8_t PROGMEM lines[F_LINES * W_LINES] =  // spaced lines {   0xff, 0xff, 0xff, 0x00, 0x00, 0xff, 0x00, 0x00,   0xff, 0xff, 0x00, 0xff, 0x00, 0x00, 0xff, 0x00,   0xff, 0xff, 0x00, 0x00, 0xff, 0x00, 0x00, 0xff, };  const uint8_t F_ARROW1 = 3; const uint8_t W_ARROW1 = 10; const uint8_t PROGMEM arrow1[F_ARROW1 * W_ARROW1] =  // arrow fading to center {   0x18, 0x3c, 0x7e, 0xff, 0x7e, 0x00, 0x00, 0x3c, 0x00, 0x00,   0x18, 0x3c, 0x7e, 0xff, 0x00, 0x7e, 0x00, 0x00, 0x18, 0x00,   0x18, 0x3c, 0x7e, 0xff, 0x00, 0x00, 0x3c, 0x00, 0x00, 0x18, };  const uint8_t F_ARROW2 = 3; const uint8_t W_ARROW2 = 9; const uint8_t PROGMEM arrow2[F_ARROW2 * W_ARROW2] =  // arrow fading to outside {   0x18, 0x3c, 0x7e, 0xe7, 0x00, 0x00, 0xc3, 0x00, 0x00,   0x18, 0x3c, 0x7e, 0xe7, 0xe7, 0x00, 0x00, 0x81, 0x00,   0x18, 0x3c, 0x7e, 0xe7, 0x00, 0xc3, 0x00, 0x00, 0x81, };  const uint8_t F_SAILBOAT = 1; const uint8_t W_SAILBOAT = 11; const uint8_t PROGMEM sailboat[F_SAILBOAT * W_SAILBOAT] =  // sail boat {   0x10, 0x30, 0x58, 0x94, 0x92, 0x9f, 0x92, 0x94, 0x98, 0x50, 0x30, };  const uint8_t F_STEAMBOAT = 2; const uint8_t W_STEAMBOAT = 11; const uint8_t PROGMEM steamboat[F_STEAMBOAT * W_STEAMBOAT] =  // steam boat {   0x10, 0x30, 0x50, 0x9c, 0x9e, 0x90, 0x91, 0x9c, 0x9d, 0x90, 0x71,   0x10, 0x30, 0x50, 0x9c, 0x9c, 0x91, 0x90, 0x9d, 0x9e, 0x91, 0x70, };  const uint8_t F_HEART = 5; const uint8_t W_HEART = 9; const uint8_t PROGMEM heart[F_HEART * W_HEART] =  // beating heart {   0x0e, 0x11, 0x21, 0x42, 0x84, 0x42, 0x21, 0x11, 0x0e,   0x0e, 0x1f, 0x33, 0x66, 0xcc, 0x66, 0x33, 0x1f, 0x0e,   0x0e, 0x1f, 0x3f, 0x7e, 0xfc, 0x7e, 0x3f, 0x1f, 0x0e,   0x0e, 0x1f, 0x33, 0x66, 0xcc, 0x66, 0x33, 0x1f, 0x0e,   0x0e, 0x11, 0x21, 0x42, 0x84, 0x42, 0x21, 0x11, 0x0e, };  const uint8_t F_INVADER = 2; const uint8_t W_INVADER = 10; const uint8_t PROGMEM invader[F_INVADER * W_INVADER] =  // space invader {   0x0e, 0x98, 0x7d, 0x36, 0x3c, 0x3c, 0x36, 0x7d, 0x98, 0x0e,   0x70, 0x18, 0x7d, 0xb6, 0x3c, 0x3c, 0xb6, 0x7d, 0x18, 0x70, };  const uint8_t F_ROCKET = 2; const uint8_t W_ROCKET = 11; const uint8_t PROGMEM rocket[F_ROCKET * W_ROCKET] =  // rocket {   0x18, 0x24, 0x42, 0x81, 0x99, 0x18, 0x99, 0x18, 0xa5, 0x5a, 0x81,   0x18, 0x24, 0x42, 0x81, 0x18, 0x99, 0x18, 0x99, 0x24, 0x42, 0x99, };  const uint8_t F_FBALL = 2; const uint8_t W_FBALL = 11; const uint8_t PROGMEM fireball[F_FBALL * W_FBALL] =  // fireball {   0x7e, 0xab, 0x54, 0x28, 0x52, 0x24, 0x40, 0x18, 0x04, 0x10, 0x08,   0x7e, 0xd5, 0x2a, 0x14, 0x24, 0x0a, 0x30, 0x04, 0x28, 0x08, 0x10, };  const uint8_t F_CHEVRON = 1; const uint8_t W_CHEVRON = 9; const uint8_t PROGMEM chevron[F_CHEVRON * W_CHEVRON] =  // chevron {   0x18, 0x3c, 0x66, 0xc3, 0x99, 0x3c, 0x66, 0xc3, 0x81, };  const uint8_t F_WALKER = 5; const uint8_t W_WALKER = 7; const uint8_t PROGMEM walker[F_WALKER * W_WALKER] =  // walking man {   0x00, 0x48, 0x77, 0x1f, 0x1c, 0x94, 0x68,   0x00, 0x90, 0xee, 0x3e, 0x38, 0x28, 0xd0,   0x00, 0x00, 0xae, 0xfe, 0x38, 0x28, 0x40,   0x00, 0x00, 0x2e, 0xbe, 0xf8, 0x00, 0x00,   0x00, 0x10, 0x6e, 0x3e, 0xb8, 0xe8, 0x00, };  void setup() {   myDisplay.begin();   myDisplay.setIntensity(0);   myDisplay.displayClear();   myDisplay.setSpriteData(pacman2, W_PMAN2, F_PMAN2, pacman2, W_PMAN2, F_PMAN2);   myDisplay.displayText("Parola sprites", PA_CENTER, 50, 1000, PA_SPRITE, PA_SPRITE); }  void loop() {   if (myDisplay.displayAnimate()) {     myDisplay.displayReset();   } }

How the code works

After setting up the display like before, the text sprites are defined.

Two constants are used to define the sprite, one for the width (number of bytes) data for one sprite and the other for the number of frames contained in the animation. The total number of bytes required is the width * number of frames. Note that the sprite data is stored in PROGMEM to save RAM space.

Each row of the array is made up of hexadecimal numbers that set which LEDs need to light up in each column of the sprite.

The example includes many different sprite definitions, which you can also find in one of the examples that come with the library.

// Sprite definitions: const uint8_t F_PMAN1 = 6; const uint8_t W_PMAN1 = 8; const uint8_t PROGMEM pacman1[F_PMAN1 * W_PMAN1] =  // gobbling pacman animation {   0x00, 0x81, 0xc3, 0xe7, 0xff, 0x7e, 0x7e, 0x3c,   0x00, 0x42, 0xe7, 0xe7, 0xff, 0xff, 0x7e, 0x3c,   0x24, 0x66, 0xe7, 0xff, 0xff, 0xff, 0x7e, 0x3c,   0x3c, 0x7e, 0xff, 0xff, 0xff, 0xff, 0x7e, 0x3c,   0x24, 0x66, 0xe7, 0xff, 0xff, 0xff, 0x7e, 0x3c,   0x00, 0x42, 0xe7, 0xe7, 0xff, 0xff, 0x7e, 0x3c, };

In the setup, the function setSpriteData(inData, inWidth, inFrames, outData, outWidth, outFrames) is used to set up user data needed so that the library can display the sprite when the PA_SPRITE animation type is selected in the displayText() function.

You can select any of the predefined sprites, in this case I used pacman2 (pacman pursued by a ghost).

          myDisplay.setSpriteData(pacman2, W_PMAN2, F_PMAN2, pacman2, W_PMAN2, F_PMAN2);   myDisplay.displayText("Parola sprites", PA_CENTER, 50, 1000, PA_SPRITE, PA_SPRITE);

The loop section is the same as before.

Conclusion

In this article, I have shown you how you can use a MAX7219 LED dot matrix display with Arduino. We looked at the basics of printing text, scrolling text, other text effects, and text sprites. There still are some less frequently used functions in the MD_Parola library that I haven't covered in this tutorial but you can check those out in the MD_Parola documentation on GitHub.

I hope you found this tutorial useful and informative. If you did, pleaseshare it with a friend who also likes electronics and making things!

I would love to know what projects you plan on building (or have already built) with this display. If you have any questions, suggestions, or if you think that things are missing in this tutorial,please leave a comment down below.

Note that comments are held for moderation to prevent spam.

Reading and Writing 8 Digit Numbers on Max7219 With Arduino

Source: https://www.makerguides.com/max7219-led-dot-matrix-display-arduino-tutorial/

8×32 MAX7219 LED dot matrix display	× 1	Amazon
8×8 MAX7219 LED dot matrix display (alternative)	× 1	Amazon
Generic 8×8 MAX7219 LED dot matrix display (alternative)	× 1	Amazon
Arduino Uno Rev3	× 1	Amazon
Jumper wires (male to female)	× 4	Amazon
USB cable type A/B	× 1	Amazon
Male headers	~ 20	Amazon
Jumpers	~ 20	Amazon

Mathews Andetter58

Reading and Writing 8 Digit Numbers on Max7219 With Arduino

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