The Bluetooth module wants 3.3v logic levels so that is taken into account. The image above shows a buffer chip doing the conversion, but the Fritzing schematic on the post uses a voltage divider.

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 setting… ...

Overall, Arduino Bluetooth Controller is a usable app, but it’s not the best option on this list. Arduino Bluetooth Controller by Giumig Apps. Giumig’s Arduino Bluetooth Controller features some of ...