Bluetooth is a popular wireless technology standard designed for data exchange over short distances. Bluetooth is so common that it’s now the part of smartphones and comes in lots of embedded devices. Many wearable devices also use Bluetooth to pair with their accessories or co-devices. The Bluetooth interface uses UHF Radio wave in ISM band from 2.4 GHz to 2.485 GHz. It was invented by telecom vendor Ericsson in 1994 and developed by Bluetooth Special Interest Group.
In lots of projects, the sensor data has been displayed on LCD modules. In many of them, the data was transferred wirelessly where the receiver section connected with a transmitter section through RF module. The transmitter section had the sensor interfaced to it while the receiver section had the LCD screen interfaced for display and monitoring of the sensor data. This project is a demonstration of monitoring sensor data on the Android phone. The android phone connects via Bluetooth interface with a transmitter section having the sensor circuit. For this purpose, HC-05 Bluetooth module is being used. The sensor used in the project is DHT-11 which relays ambient temperature and humidity values to the microcontroller.