Getting started with the Raspberry Pi

This repository goes hand in hand with this blog post and contains some basic examples of controlling GPIO lines on the Raspberry Pi with the use of an RGB LED using C and C++.

This is all very basic stuff, but should provide a very simple starting block for anyone new to the world of Raspberry Pi.

Contents

• Repository Contents
• Building
  • Blog only
  • Demo only
• Running
  • led_select (C application)
  • led_demo (C++ application)

Repository Contents

This repository contains a very small number of files:

• led_demo.cpp - Demo C++ application source
• led_select.c - Code used within the blog post
• Makefile - The makefile for the C and C++ applications
• Readme.md - This Readme file

Building

This repository contains a Makefile, which should allow a simple call to make:

pi@raspberrypi:~ $ make
Building led_demo
Successfully built led_demo
Building led_select
Successfully built led_select

and to clean, simply run make clean:

pi@raspberrypi:~ $ make clean
Clean complete.

Blog only

To build just the blog application (led_select), run:

pi@raspberrypi:~ $ make led_select
Building led_select
Successfully built led_select

or

pi@raspberrypi:~ $ gcc led_select.c -Wall -Wshadow -Wpedantic -lwiringP -o led_select

Demo only

If you wish to build the demo application (led_demo), run:

pi@raspberrypi:~ $ make led_demo
Building led_demo
Successfully built led_demo

or

pi@raspberrypi:~ $ g++ led_demo.cpp -Wpedantic -Wshadow -Wall -lwiringPi -lpthread -o led_demo

Note the library requirements: wiringPi and pthread (required for software PWM)

Running

led_select

This is the source used to build the blog example C application. This provides a very basic application that takes a single argument: red, green or blue.

pi@raspberrypi:~ $ ./led_select red
Turning the red LED on.

led_demo

This is the source used to build a C++ application, which gives a more detailed example of things that can be done with an LED, including:

• mixing colours
• hardware PWM
• software PWM

Run the application ./led_demo and follow the instructions on screen.

pi@raspberrypi:~ $ ./led_demo
Enter a letter from the following:
* R (Red)
* G (Green)
* B (Blue)
* C (Cyan)
* M (Magenta)
* Y (Yellow)
* W (White)
* F  Free run - changes colour forever.
* P  Pulse - pulses the green LED forever (hardware PWM).
* S  Software PWM pulse - changes colour forever with software PWM fades.
* X  Exit