Cpu graph on MAX7219 8x8 led matrix display

Quick about the project

This project is inspired by THIS PROJECT which reads CPU usage and turns on several LEDs. My implementation rather uses 8x8 matrix display where I wanted to show CPU usage as a history graph. From mentioned project I used 'get_cpu_usage' which reads Linux' /proc/stat file and wrote my logic to draw CPU history graph.

How it's working

• It's written in C++.
• It uses popular WiringPi lib to control GPIOs.
• It uses Max7219 library I created based on THIS CODE to easy communicate with 8x8 display using any 3 digital pins. HERE you can find additinal information about commands that MAX7219 can receive so you can customize it as you like. MAX7219 is a chip that drives 8x8 display.

Instalation

1. Install WiringPi: http://wiringpi.com/download-and-install/
2. Clone this project
3. Run 'make' to build executable
4. Execute with 'sudo ./cpugraphpi 1000' (1000 means 1000ms delay after each reading)

Wiring the display with Raspberry Pi

The code is set to use these pins but you are free to change them:

+5V/VCC:     Rpi header pin 2
GND:         Rpi header pin 6

DATA/DIN:    0 - GPIO 17 (WiringPi pin num 0) Rpi header pin 11
CLOCK/CLK:   3 - GPIO 22 (WiringPi pin num 3) Rpi header pin 15
LOAD/CS:     4 - GPIO 23 (WiringPi pin num 4) Rpi header pin 16