Ruby Bindings for libbcm2835

The BCM2835 is the ARM11 core used in the Raspberry PI. It exposes several harware peripherals:

• GPIO
• SPI
• I²C
• UART

This library is a wrapper on top of libbcm2835 that provides a high level interface for accessing the ARM's hardware features from Ruby

View the Full Documentation on rubydoc.info

GPIO

General Purpose Input/Output

Using Inputs

pin = 17

# make pin an input
GPIO.input(pin)

# check if the input is HIGH i.e. true
puts "door is closed" if GPIO[pin]

Using Outputs

pin = 17

# make pin an output
GPIO.output(pin)

# blink
loop do
  GPIO[pin] = true
  sleep(1)
  GPIO[pin] = false
  sleep(1)
end

SPI

Serial Peripheral Interface

Reading from the SPI bus

SPI.begin do |spi| 
  puts spi.read       # returns 1 byte
  puts spi.read(1024) # returns an array of 1024 bytes 
end

Writing to the SPI bus

SPI.begin do |spi| 
  spi.write(0x22)           # write 1 byte
  spi.write("hello")        # write 5 bytes
  spi.write(0x22,0x45,0x71) # write several bytes at once 
end

I²C

Two Wire Interface

Not yet implemented

UART

Universal Asynchronous Receiver/Transmitter

You can use the Ruby Standard Library to read and write from the UART

Echo Example

File.open('/dev/ttyAMA0', 'a+') do |file|
  loop do 
    data = file.read
    file.puts(data)
  end
end

Installation

Add this line to your application's Gemfile:

gem 'bcm2835'

And then execute:

$ bundle

Or install it yourself as:

$ gem install bcm2835

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request