raspi-gpio-rb

🔌 A simple and light interface to interact with GPIO pins of the Raspberry Pi.

This library uses /sys/class/gpio interface to communicate with GPIO pins. It doesn't require super-user rights, therefore everyone on the OS can use it.

• 📌 Requirements
• 🔧 Setup
  • Quick installation
  • Gemfile
  • Build
• ⌨ Basic interactions
  • Defining a pin
  • Reading pin's value
  • Outputing a value
• 🔐 License

📌 Requirements

This library requires an updated version of Ruby, and a Raspberry Pi with Raspbian installed on.

The raspi-gpio library has been tested on models : 3B

🔧 Setup

Quick installation

If you want to quickly test the library, you can install it using the install command of Ruby Gem.

gem install raspi-gpio

Gemfile

If you setup the library for medium or big projects, it's recommended to write it in your Gemfile.

gem 'raspi-gpio', '~> 1.0'

After, use again the install command, but without the package name.

gem install

Build

You can also compile it by yourself. First, clone the repository.

git clone https://github.com/exybore/raspi-gpio-rb.git  # HTTP
          git@github.com:exybore/raspi-gpio-rb.git      # SSH

Then, build the gemspec file to create the gem.

gem build ./raspi-gpio.gemspec

Finally, install it on your system.

gem install ./raspi-gpio-1.x.x.gem

⌨ Basic interactions

First of all, we must include the library in our project. That can be achieved really easily with the require keyword.

require 'raspi-gpio'

# ...

Defining a pin

A GPIO pin is defined with three things :

• a pin number (the number of total pins depend on your Raspberry model)
• a direction (in or out)
• a value (low or high)

The GPIO class is the way the library provides to register our pins. The initialization method takes 2 arguments :

• the pin number to use
• the direction (default : out)

We can use the OUT and IN constants for the direction.

pin = GPIO.new(9, OUT)

The direction of a pin can be changed at any point of the code using the set_mode method.

pin.set_mode(IN)

Reading pin's value

To read the pin value, we're going to use the get_value method.

pin.get_value

# Example output : 0

• If the pin direction is IN, it'll read the power that goes into it
• If it's in OUT, it'll output the value that we defined earlier

Outputing a value

To set the value of a pin, the GPIO class has a set_value method that can take two values :

• 0, no power (low)
• 1, maximum power (high)

The LOW and HIGH constants are here to let us set them while keeping code clarity.

# Imagine that a LED is connected to our pin.

pin.set_value(HIGH)

# Output : the LED is on

pin.set_value(LOW)

# Output : the LED is off

🔐 License

See the license file.