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MAX7219 Dot Matrix

An 8x8 LED matrix display powered by the MAX7219 driver chip, easily cascaded for larger displays.

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MAX7219

The MAX7219 module simplifies the process of controlling a grid of 64 individual LEDs (8x8). Using an SPI-like serial interface, you only need 3 data pins to control the entire matrix. Multiple modules can be daisy-chained together for scrolling text displays.

DisplaysMatrixSPI

Overview

Driving 64 LEDs individually would require 64 pins, or at least 16 pins with complex multiplexing logic in code. The MAX7219 chip handles all the multiplexing, refreshing, and current-limiting for you.

Pin Reference

Pin	Type	Description
VCC	power	Power Supply. Connect to Arduino 5V.
GND	power	Ground. Connect to Arduino GND.
DIN	input	Data In (SPI MOSI). Connect to Arduino D11 (or another digital pin).
CS	input	Chip Select / Load. Connect to Arduino D10 (or another digital pin).
CLK	input	Clock (SPI SCK). Connect to Arduino D13 (or another digital pin).
VCC_OUT	power	Passed-through VCC for daisy-chaining the next module.
GND_OUT	power	Passed-through GND for daisy-chaining.
DOUT	output	Data Out. Connect to `DIN` of the next matrix module.
CS_OUT	output	Passed-through Chip Select for the next module.
CLK_OUT	output	Passed-through Clock for the next module.

Configurable Attributes

Attribute	Type	Default	Description
color	string	red	The color of the LEDs in the simulator (e.g., `red`, `green`, `blue`).

Wiring Diagram

Example Arduino Code

This example uses the popular LedControl library to draw an 'X' pattern on the matrix. Install it via the Library Manager.

#include <LedControl.h>

// LedControl(DataIn, CLK, CS, numDevices)
LedControl lc = LedControl(11, 13, 10, 1);

void setup() {
  // Wake up the MAX7219 from power-saving mode
  lc.shutdown(0, false);
  
  // Set brightness to a medium value (0-15)
  lc.setIntensity(0, 8);
  
  // Clear the display
  lc.clearDisplay(0);
  
  // Draw an 'X' shape
  // setRow(device_index, row_index, binary_data)
  lc.setRow(0, 0, 0b10000001);
  lc.setRow(0, 1, 0b01000010);
  lc.setRow(0, 2, 0b00100100);
  lc.setRow(0, 3, 0b00011000);
  lc.setRow(0, 4, 0b00011000);
  lc.setRow(0, 5, 0b00100100);
  lc.setRow(0, 6, 0b01000010);
  lc.setRow(0, 7, 0b10000001);
}

void loop() {
  // Display is static
}

Simulation Notes

• You can chain multiple MAX7219 modules in the simulator by connecting DOUT of one to DIN of the next, passing along CS, CLK, VCC, and GND. Update numDevices in the LedControl constructor accordingly.

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