#Control Hardware Remotely With Socket.IO

The purpose of the code is to illustrate a simple Internet of Things setup where an LED connected to a Raspberry Pi can be controlled from a web page via the use of web sockets.

Hardware Setup

You can connect the LED to any GPIO pin available on your Pi. For the purposes of the video I was using an LED hooked up in the active low configuration meaning the LED will turn on when the GPIO pin is driven low.

Fix Node on the Pi

As of January 2017 on the current Raspbian Jessie image the version of Node.js installed by running sudo apt-get install nodejs no longer compiles native addons correctly. This prevents the required rpi-gpio package to fail on npm install. To fix this you must remove any existing Node.js installation from your Pi using the following commands.

sudo apt-get remove nodejs
sudo apt-get remove npm
sudo apt-get remove nodejs-legacy

Once removed you can install current versions of Node by running the following:

curl -sL https://deb.nodesource.com/setup_7.x | sudo -E bash -
sudo apt-get update
sudo apt-get install nodejs

This will install current versions of Node and NPM.

Server Code

The code located in the server folder can run locally or in a Heroku instance without any changes. To run locally just install the Node module dependencies and launch. From the server folder run the following commands.

npm install
npm start

Client Code

The client code contained in client/app.js needs to be copied to your Raspberry Pi along with client/config.js and run there. It assumes your LED is hooked up in the active-low configuration as illustrated above. You must also modify config.js to indicate your LED pin and server url. Once copied to your Pi you can run the client like this:

npm install rpi-gpio
npm install socket.io-client
sudo node app.js

Don't forget the 'sudo' or your client will run but lack the ability to change the LED state

You only need to install the module dependencies the first time.