Getting Started Example with the Onion Omega & Python

In this quick tutorial you’ll learn how to control the in-built LED in the expansion dock using Python.

Time required: < 5 minutes

Python Example

Installation

First you’ll need to install python & also git for this example. To do this run the following commands from the console

opkg update
opkg install python-light git git-http

This will take a few moments, once complete let’s grab the example code from GitHub by running these commands:

cd /root
git clone https://github.com/BravoPapa/OmegaGPIO

Running the Example

Excellent, let’s now change directories and run the example python script.

cd OmegaGPIO 
python gpio_demo.py

The RGB LED on your expansion dock will now be rotating through red, green & blue.

Neat eh?

Using the GPIO Functions

Take a look at omega_gpio.py file to see the available functions that can be used in your own Python projects.

Using a GPIO as Output

Here is a small sample of code that sets GPIO13 to HIGH and then LOW 5 seconds later:

import omega_gpio
import time

# initialize the pin
gpioNum = 13
omega_gpio.initpin(gpioNum,'out')

# set the pin to HIGH
omega_gpio.setoutput(gpioNum, 1)

# wait 5 seconds and set to LOW
time.sleep(5)
omega_gpio.setoutput(gpioNum, 0)

# release the pin
omega_gpio.closepin(gpioNum,'out')

Using a GPIO as Input

This sample of code shows how to read and print the input value of a GPIO every 5 seconds for a minute:

import omega_gpio
import time

# initialize the pin
gpioNum = 26
omega_gpio.initpin(gpioNum,'in')

# perform 12 reads, each 5 seconds apart
for i in range (0, 12):
	print 'GPIO%d value: %d'%(gpioNum, omega_gpio.readinput(gpioNum) )
	time.sleep(5)

# release the pin
omega_gpio.closepin(gpioNum,'out')

Further Reading

A huge hat-tip to Brian Piersel for posting this example code in the community forums.

And a thank you from Onion to Matthew Ogborne for writing this tutorial.

More details on the Onion Omega GPIO Pins can be found here.