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.

[Dastardly] makes a homemade daughterboard–er, shield–to connect it to the Arduino. ... If you need help reprogramming the HC-05 Bluetooth module, we’ve covered that before.

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 ...