The HC-05, a Bluetooth to serial bridge, can be found for around $5 on the internet and therefore may be the cheapest way to add Bluetooth connectivity to your project. However, its default ...

It’s hard to imagine an easier way to set up communications between an Android device and an Arduino using Bluetooth ... the cheap and ubiquitous HC-05 Bluetooth module. Having picked up one ...

Android apps for Arduino ... serial interface. This works well if your board connects to your computer via a USB cable and a USB-to-serial chip, but some applications might require a wireless option.