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INTERNET OF THING (IoT)

LIBRARIES

Arduino - LED Matrix

LED matrix display, also known as LED display, or dot matrix display, are wide-used. In this tutorial, we are going to learn:

LED matrix
How to connect Arduino to 8x8 LED matrix
How to connect Arduino to 32x8 LED matrix
How to connect Arduino to display text, numbers, and animated effects on the LED matrix.

After that, you can easily adapt the code for other LED matrices such as 16x8 LED matrix, 64x8 LEd matrix ...

Hardware Required

1	×	Arduino UNO or Genuino UNO
1	×	USB 2.0 cable type A/B (for USB-A PC)
1	×	USB 2.0 cable type C/B (for USB-C PC)
1	×	FC-16 LED Matrix 32x8
1	×	FC-16 LED Matrix 8x8
1	×	Generic LED Matrix 8x8
1	×	Jumper Wires
1	×	DC Power Jack
1	×	5V Power Adapter for Arduino
1	×	(Recommended) Screw Terminal Block Shield for Arduino Uno
1	×	(Recommended) Breadboard Shield For Arduino Uno
1	×	(Recommended) Enclosure For Arduino Uno

Or you can buy the following sensor kits:

1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some links in this section are Amazon affiliate links. If you make a purchase through these links, we may earn a commission at no extra cost to you.
Additionally, some links direct to products from our own brand, DIYables.

About LED Matrix

LED Matrix display

There are many kinds of LED Matrix. With Arduino, the MAX7219-based LED matrix is widely used. MAX7219-based LED matrix has the following features:

A base unit of an LED matrix is a block
Each block has an 8x8 LED matrix (64 LED) and a MAX7219 driver.
There are two popular block forms: the generic module and the FC-16 module.
A LED matrix can be composed of a single block or multiple blocks in a daisy-chain
You can buy a pre-built multiple-block LED Matrix (e.g. 4-in-1, 8-in-1)
You can also buy multiple blocks and wire them to form a LED matrix with the desired size.
You will declare the size of the LED matrix you use in the Arduino code.

Pinout

LED Matrix Pinout

A LED Matrix is formed by a single or multiple blocks. Each block includes two groups of pins:

Input pins group:

VCC: connected to 5V.
GND: connected to GND.
DIN is the Data pin, Connect it to SPI MOSI pin of the Arduino.
CS: Chip Select, Connect it to any digital pin of the Arduino.
CLK: Clock pin, Connect it to SPI CLK pin of the Arduino.

Output pins group:

VCC: connects to VCC on the next module.
GND: connects to GND on the next module.
DOUT: Data Out, connects to the DIN pin of the next module.
CS: connects to CS on the next module.
CLK connects to CLK on the next module.

Wiring Diagram

If the LED matrix is made of a single block:

Connect the input pins groups to Arduino
Let the output pins group unconnected

Arduino 8x8 LED matrix FC-16 wiring diagram

This image is created using Fritzing. Click to enlarge image

Arduino 8x8 LED matrix generic wiring diagram

This image is created using Fritzing. Click to enlarge image

If the LED matrix is pre-built multiple blocks:

Connect the input pins groups to Arduino
Let the output pins group unconnected

Arduino LED matrix display wiring diagram

This image is created using Fritzing. Click to enlarge image

If the LED matrix is made of multiple blocks by yourself:

Connect the input pins groups of the first block to Arduino
Connect the output pins groups of each block to the input pins groups of the next block
Let the output pins group of the last block unconnected

Arduino 32x8 LED matrix wiring FC-16 diagram

This image is created using Fritzing. Click to enlarge image

Arduino 32x8 LED matrix wiring generic diagram

This image is created using Fritzing. Click to enlarge image

Because the display draws a lot of currents (up to 1A at maximum brightness):

Do not use the power from the 5V pin of Arduino.
Use an external 5V power supply instead. Arduino and LED matrix can share power from a 5V power adapter

Because Arduino connects to LED matrix via SPI pins:

Pin 13 (SCK) and 11 (MOSI) on Arduino Uno must be used. If you’re using another Arduino board, check the official documentation for equivalent SPI pins.
Pin 3 (CS) can be changed to any pin

How To Program For LED Matrix

It is not easy to control the LED matrix. Fortunately, libraries are available to make it easy. Below is a step-by-step on how to write Arduino code to control the LED matrix

Include libraries:

#include <MD_Parola.h> #include <MD_MAX72xx.h>

Specify which hardware is being used: GENERIC_HW or FC16_HW.

#define HARDWARE_TYPE MD_MAX72XX::FC16_HW

Define how many LED block is used. for example, a 4-in-1 LED matrix has 4 blocks.

#define MAX_DEVICES 4

Define the pin that connects to the LED matrix’s CS pin. For example, pin D3

#define CS_PIN 3

Create a new instance of the MD_Parola class for the LED matrix display.

MD_Parola ledMatrix = MD_Parola(HARDWARE_TYPE, CS_PIN, MAX_DEVICES);

Code in the setup() function:

void setup() { ledMatrix.begin(); // initialize the object ledMatrix.setIntensity(0); // set the brightness of the LED matrix display (from 0 to 15) ledMatrix.displayClear(); // clear led matrix display }

Display text, number and show animated effects: see next part

Arduino - LED Matrix Code

The below code is for 32x8 FC-16 LED matrix display (4 blocks). But you can easily adapt it for 8x8, 16x8, 64x8...

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-led-matrix */ #include <MD_Parola.h> #include <MD_MAX72xx.h> #define HARDWARE_TYPE MD_MAX72XX::FC16_HW #define MAX_DEVICES 4 // 4 blocks #define CS_PIN 3 // create an instance of the MD_Parola class MD_Parola ledMatrix = MD_Parola(HARDWARE_TYPE, CS_PIN, MAX_DEVICES); void setup() { ledMatrix.begin(); // initialize the object ledMatrix.setIntensity(15); // set the brightness of the LED matrix display (from 0 to 15) ledMatrix.displayClear(); // clear LED matrix display } void loop() { ledMatrix.setTextAlignment(PA_LEFT); ledMatrix.print("Left"); // display text delay(2000); ledMatrix.setTextAlignment(PA_CENTER); ledMatrix.print("Center"); // display text delay(2000); ledMatrix.setTextAlignment(PA_RIGHT); ledMatrix.print("Right"); // display text delay(2000); ledMatrix.setTextAlignment(PA_CENTER); ledMatrix.setInvert(true); ledMatrix.print("Invert"); // display text inverted delay(2000); ledMatrix.setInvert(false); ledMatrix.print(1234); // display number delay(2000); }

Quick Steps

Connect Arduino to LED matrix as above wiring diagram
Connect Arduino to PC via USB cable
Navigate to the Libraries icon on the left bar of the Arduino IDE.
Search “MD_Parola”, then find the MD_Parola library
Click Install button.

Arduino MD_Parola library

You will be asked to install the MD_MAX72XX library for dependency. Click Install All button.

Arduino MD_MAX72XX library

Copy the above code and open it with Arduino IDE
Click Upload button on Arduino IDE to upload code to Arduino
See the LED matrix display

Arduino LED Matrix Code – Scrolling Text

When you want to print a long message that is too long to fit on a LED matrix display, you can use the scroll text effect technique.

The below Arduino code shows how to scroll a message on the LED matrix display.

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-led-matrix */ #include <MD_Parola.h> #include <MD_MAX72xx.h> #define HARDWARE_TYPE MD_MAX72XX::FC16_HW #define MAX_DEVICES 4 // 4 blocks #define CS_PIN 3 // create an instance of the MD_Parola class MD_Parola ledMatrix = MD_Parola(HARDWARE_TYPE, CS_PIN, MAX_DEVICES); void setup() { ledMatrix.begin(); // initialize the object ledMatrix.setIntensity(15); // set the brightness of the LED matrix display (from 0 to 15) ledMatrix.displayClear(); // clear led matrix display ledMatrix.displayScroll("Hello, DIYables", PA_CENTER, PA_SCROLL_LEFT, 100); } void loop() { if (ledMatrix.displayAnimate()) { ledMatrix.displayReset(); } }

For more text effects, please visit MD_Parola Library Reference.

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