GPIO Hardware Control: BLINK

Home | Initial Setup

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Purpose

This document explains the procedure for controlling GPIO pins (Writing and Reading) using the galile-io library.

This exercise is based on a more extent explanation of Node.JS by Nicolas Vailliet here:

• Intel Software Academic Program

Status and Disclaimer

This WIKI page is a living document that may be changed at any moment without prior notice.

All procedures and instructions shared in this GIT Hub Account are given to you "as-is" without any implicit or explicit warranty of success.

To the extent permitted by law, I accept no liability or responsibility for any damage or loss you may get into while following this procedure.

As of the time this post was written, I am affiliated to Intel Corporation as a regular employee based in Costa Rica, working as an Applications Developer.

All content in this page is provided voluntarily and personally independently of Intel.

Pre-requisites

You need:

• Perform the Boot from SD Card procedure (Optional)
• Perform the Connecting through LAN procedure

Procedure

STEP 1: Connect to your Galileo Board using puTTY via LAN

• You can use Connecting through LAN procedure

STEP 2: Once in the Linux environment, set the date/time by executing date mmddhhmmYY

• example for May 20, 12:57pm: date 2005125714

This will make node.js run better; especially when running the npm (nodejs package manager)

STEP 3: Install galileo-io npm package

• Using the puTTY terminal, create a folder to store your code. i.e.: /home/root/gpioexamples
  • cd /home/root
  • mkdir gpio_examples
• Access the folder you just created
  • cd /home/root/gpio_examples
• Install galileo-io npm package
  • npm install galileo-io

This will install galileo-io package in your current project (folder) under node-packages folder.

STEP 3: BLINK

• Using vi text editor create a new JS file named "blink.js"

logMessage("Script Begins!");
var Galileo = require("galileo-io");
var board = new Galileo();
var pin = 9;
var byte = 0;

/*
 * Contains the logic for when the Galileo Board is Ready
 * @returns {undefined}
 */
function galileoReadyHandler(){
   logMessage("galileoReadyHandler() Begins!");
   this.pinMode(pin, this.MODES.OUTPUT);
   logMessage("Pin was just set as OUTPUT");
   setInterval(intervalHandler, 500);
   logMessage("Interval was just set to 500ms");
}

/*
 * Writes to the designated blink pin toggling between 0 and 1. This function is to be called by an Interval (timer) handler.
 * @returns {undefined}
 */
function intervalHandler(){
   logMessage("intervalHandler() Begins!");
   board.digitalWrite(pin, (byte ^= 1));
   logMessage("digitalWrite() just happened!");
}

/***
 * Logs messages into the console including a milliseconds timestamp
 * @param {type} message
 * @returns {undefined}
 */
function logMessage(message){
   var d = new Date().getTime();
   console.log(d + " - " + message);
}

/***
 * This line sets up the Ready event of the Galileo Board to be handled by galileoReadyHandler function.
 * @param {type} param1
 * @param {type} param2
 */
board.on("ready", galileoReadyHandler);

• Connect an LED to the Galileo Board as follows

• run the file in node.js by executing node blink.js
• The system will blink a signal in pin 9. It will also show different debug information in the console.

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Home | Initial Setup