Cgpio

A simple GPIO Wrapper in Ruby (which uses C memory mapping to access the GPIO)

require 'cgpio'

# switch on a led on port 48
led = Cgpio.new(48)
led.on

Tested with Linux-Kernel Version "4.1.6" on

Beaglebone Black

WARN: the gem is not stable yet!

Features

set/get value
set/get direction
virtual GPIO
memory mapped GPIO access

Installation

This gem uses C extension, so you need build-essentials (gcc, make)

gem install cgpio

Usage

Example

require 'cgpio'

# setup a new port (output is default)
led = Cgpio.new(48)

# setup a new input port
switch = Cgpio.new(66, direction: :in)

# connect led with switch
loop do led.value = switch.value end

Initializing a port

# setup a new port (output is default)
led = Cgpio.new(48)

# setup a new output port with HIGH as initial state
led = Cgpio.new(66, value: true)

# setup a new input port
switch = Cgpio.new(66, direction: :in)

Note: The initialization will export the port (/sys/class/gpio/export) if it is not exported already. But when the GC (Garbage Collector) deletes this object, the port will not be unexported.

Set direction of port

# port as output
led.direction = :out

# port as input
switch.direction = :in

Get direction of port

# returns :in or :out
dir = switch.direction

Set value of port

# set value to true
led.value = true
# or
led.on

# set value to false
led.value = false
# or
led.off

Read value of port

val = switch.value
val = switch.on?
val = switch.off?

Get static info about port

# get port number
nr = port.nr

Virtual GPIO

When you want to run your program on a hardware which don't have GPIO, you can use virtual GPIOs.

For this you have to configure the Cgpio before you use it:

# put this at the beginning of your program
Cgpio.configure do |config|
    # use virtual gpio instead of real gpio
    config.virtual = true
end

Value changed event

You can can define a function which will be called when the value of the virtual GPIO changes:

# will be called when value changes
led.value_change do |new, old|
    puts "led change value from #{old} to #{new}"
end

License

The gem is available as open source under the terms of the MIT License.

cgpio

Development