matrix of LEDs with Arduino in C language

Learn how to draw on a matrix of LEDs with Arduino in C language
Each time, the idea is to get rid of the facilities offered by the famous "Arduino language" in the standard IDE. Here, the programs will be developed in pure C language using the tools of the avr-gcc compilation chain.

The objective is twofold:

Develop optimized, efficient and compact codes;
Demystify the operation of a microcontroller and take control of inputs / outputs, without a makeup, by directly attacking the registers of the microcontroller.
In this third part, the author details the operation of a 7 x 5 LED array and the multiplexing technique he developed to develop a C library to draw characters.
Download full project from here:  http://adf.ly/1mCrfy