ESP32 and Max7219 8×8 LED matrix example

The MAX7219/MAX7221 are compact, serial input/output common-cathode display drivers that interface microprocessors (µPs) to 7-segment numeric LED displays of up to 8 digits, bar-graph displays, or 64 individual LEDs.

Included on-chip are a BCD code-B decoder, multiplex scan circuitry, segment and digit drivers, and an 8×8 static RAM that stores each digit.

Only one external resistor is required to set the segment current for all LEDs. The MAX7221 is compatible with SPI™, QSPI™, and MICROWIRE™, and has slew-rate-limited segment drivers to reduce EMI.

Here is a picture of a typical module that can be bought from many sources, including the link at the end of the article

Schematics

Code

You will need the library from https://github.com/squix78/MAX7219LedMatrix installed


#include <SPI.h>
#include "LedMatrix.h"

#define NUMBER_OF_DEVICES 1
#define CS_PIN 15
LedMatrix ledMatrix = LedMatrix(NUMBER_OF_DEVICES, CS_PIN);

void setup()
{
ledMatrix.init();
ledMatrix.setIntensity(4); // range is 0-15
ledMatrix.setText("The quick brown fox jumps over the lazy dog");
}

void loop()
{
ledMatrix.clear();
ledMatrix.scrollTextLeft();
ledMatrix.drawText();
ledMatrix.commit();
delay(200);
}

Output

A video of what you should expect to see appeared to be a good idea at the time, here you go

 

Links
You can get these from around $2 a piece

MAX7219 dot matrix display module

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