MAX7219-Matrix

Interfacing with MAX7219 8x8 LED arrays for the Raspberry Pi over SPI

Install

npm install max7219-matrix

Dependencies

The SPI device needs to be enabled on your Raspberry Pi. Sparkfun tutorial on how to do this

Check in /dev if the devices installed successfully:

$ ls -l /dev/spi*
crw-rw---- 1 root spi 153, 0 Aug 14 22:22 /dev/spidev0.0
crw-rw---- 1 root spi 153, 1 Aug 14 22:22 /dev/spidev0.1

Wiring

How to use the package

let maxMatrix = require("max7219-matrix");

let m = new maxMatrix.MAX7219Matrix("/dev/spidev0.0", 4);
m.processText("TEST");

Run node example/demo.js to run the snippet from above --- The demo is set for 4 LED Arrays.

• The displayed text will always be trimmed to the first N characters, where N is the number or screens specified in the constructor. ex.: If we set the screen count to 4, and we send the text "APPLE" (max7219.processText("APPLE");), our screen will display APPL.

maxMatrix.MAX7219Matrix(device, screenCount)

• Constructor
• Creates an instance of the object, and initializes it with the required values.
• The device argument specifies the SPI Device to which the screens are connected. ex.: "/dev/spidev0.0".
• The screenCount argument specifies the number of daisy-chained MAX7219 driven 8x8 LED arrays ex.: 4.

setBrightness(brightness)

• Set the brightness of the matrices.
• brightness should be between 0 and 15 (inclusive)

processText(text, font)

• Display the text, in the selected font. If the font is not specified, it defaults to CP437_FONT.
• The following fonts can be used:
• CP437_FONT, SINCLAIR_FONT, LCD_FONT, UKR_FONT, TINY_FONT, CP437_FONT_ROTATED (default), SINCLAIR_FONT_ROTATED and LCD_FONT_ROTATED.
• Syntax :

m.processText("TEST", "SINCLAIR_FONT_ROTATED");

Example

The demo, found at example/demo.js, displays " TEST " in the SINCLAIR_FONT_ROTATED. (it's set for 4 daisy-chained MAX7219 matrices)

TO-DOs

• Text rotation
• Scrolling text
• "Breathing" text effect
• "Blinking" text effect

Notes

This is a project I work on in my spare time, and it's very much a work-in-progress. If you have any problems, open an issue on GitHub. Pull requests are very welcome! Any improvements made to the code are much appreciated.

Special thanks to

• Larry Bank (bitbank2), and his awesomely documented C++ project.