C++ library for driving a LED Dot Matrix with MAX7219 ICs through SPI.

This library provides some abstractions around the linux spidev, in order to drive a dot matrix through a (series of) MAX7219 IC(s). Check out test/main.cpp for a quick primer on how to use the library.

Building library

Follow these steps to build this library (and test code).

1. Install premake5
2. Enable SPI (necessary on RPi)
3. Configure build with premake5 gmake2
4. Build library with make
5. Run test-script ./bin/LDMTest

Using this library

You can follow the steps above to generate a library file, which you can then use in any project.
Another way of using this library, is to clone this repository in a subfolder of your project (eg. git submodule), and include it in your own premake file:

workspace "YourWorkspace"
  -- Workspace related configurations

  -- Include LDM library as a premake project
  include "path/to/ldm-library/ldm.lua"

project "YourProject"
  -- Create your project here

  -- useLDM is a utility function which adds the necessary includes and links the LDM project
  useLDM "path/to/ldm-library"

Check out the premake5.lua of this repo for an example.

Assumptions

This library was build around the 4-in-1 MAX7219 led dot matrices, and as such is built with a few assumptions in mind:

• The different 8x8 matrices are layed out in a single row.
• The MAX7219 are cascaded such that the rows of each 8x8 matrix get programmed at the same time (through SPI cascading).
• The last matrix in the cascade contains the point of origin (0, 0) in the top-left corner.

If your use-case does not conform with these assumptions, you will have to modify this library or look elsewhere for a different library. The 2 last assumptions can be quite easily fixed by modifying the flush() method in src/matrix.cpp.