In this chapter, we interfaced a relay to the Arduino board and the Ethernet shield so that it can be controlled remotely. To do so, we used two different approaches, each with their own advantages and disadvantages. First, we kept things local and controlled the relay from within your local network. This solution has the advantage that even if your Internet connection is down, the project still works.
Then, we used a dedicated web service to control the relay from anywhere. This is clearly an advantage of the latter approach; however, it will not work if your Ethernet shield is not connected to the web.
The following were the major takeaways from this chapter:
First, we chose the different components for the project, and assembled them so that we can control a device from the Arduino board such as a desk lamp.
Then, we wrote the first sketch to test the project by simply switching the relay on and off.
After that, we built the first application based on the hardware we just assembled...