“I wanted to build a bluetooth temperature sensor which I could use to read remotely the temperature in my green house. I decided that the first step would be to build a prototype on a breadboard. This project describes the construction and operation of the prototype, i.e. how a remote temperature reading may be viewed on an Android Phone or laptop.
Temperature is read from a low cost temperature sensor using a small but powerful microprocessor - ATTINY85 - and transmitted to a PC or Android Phone using a HC-06 bluetooth sensor.
The basic principle is that a serial connection is set up between the ATTINY85 chip and the user device via a bluetooth chip (HC-06).”