If you are looking to connect a BLE (Bluetooth 4.0) module instead of Bluetooth 2.0 module, please see my new tutorial: How to control Arduino with HM-10 (CC2541) BLE module and a mobile app.
Technology is progressing at break-neck speed, everyone of us has smart phones now-a-days, there are cool apps which let us stay in contact with our friends and family, get latest weather information or stay-updated with latest news but what's next? All of these are old-school techs by now, what is the next use of this amazing processing speed and cutting-edge communication method we carry around with us all times? If I say you can control the lights of your home, know that if heating is on? or if your mobile phone automatically shuts off your air conditioner? Ring bells?
Of course, here on Instructables, we all know these uses and using this tutorial we will build a circuit and control it through the mobile app and we will do it very rapidly, let's say you will be able to control lights of your home in under 20-30 minutes? Uh-oh, not really the lights but for brevity's sake we will be controlling an LED for now and you can add all kinds of circuitry later!
Let's start, we will need:
Let's go forward to the next step and start building our circuit!
HC-05 is a serial port module which makes it very easy to use. If you see the pin configuration of HC-05, there are total 6 but we only need 4 middle ones for our set-up.
Now power-up the Uno using USB cable, a red light LED on HC-05 will start blinking, means we are ready to go forward to the next step!