Posted on May 30th, 2014
Control physical devices using an Arduino based home automation controller that connects to your network and lets you switch things on and off using a web browser. This episode shows the construction sequence of a controller that combines an Arduino-compatible board, Power-over-Ethernet, and relay driver shields to create a self-contained controller that can serve up its own web interface so you can click buttons in your browser to turn devices on and off.
View directly on YouTube: youtu.be/jvuvyiyVqtc
As shown in the video, decide how your device will be mounted and where you want external connections such as the Ethernet cable to be located. Drill suitable holes in the case and mount your Arduino in place. It can be a good idea to use plastic screws as shown in the video to prevent any possibility of short circuits to the outside of the case.
There are many options for software to control the device. For example, you could have it subscribe to an MQTT broker (server) and update its outputs based on publications from other devices. Or you could provide a menu via the serial console to control it manually from a computer connected via USB.
For this example I’ve provided a sketch that runs as a web server via Ethernet, and serves up a web page that includes “on” and “off” buttons for each of 16 outputs. By loading the web page in your browser you can simply click the appropriate buttons to activate and deactivate devices connected to those outputs. This example uses two Relay 8 shields, but it works just fine with a single shield as well. There’s no harm having the extra buttons visible and nothing will be damaged if the Arduino tries to address outputs that don’t exist, but you can trim it down to only 8 outputs if you prefer. It can also be scaled up to 24, 32, etc outputs if required.
You can see the full source code for the sketch at https://github.com/SuperHouse/OutputControllerRelay8x2. There are plenty of comments in it to help explain how it works.