Introduction: A Simple Temperature and Humidity Monitor With Bluetooth Using Arduino

About: An electronics hobbyist

You have seen temperature and humidity display board from your childhood right??So let us build now.

Prerequisites - basic knowledge of C and Arduino programming and hardware interfacing(basic). I have used the DHT22 sensor for temperature and humidity display. It is highly accurate.For a cheaper sensor you can go for DHT11. The schematics and code are given at the Fritzing file.Before opening it,download the free software Fritzing first. It is very nice.I have attached a 16*2 display board for the temperature and humidity display.Now I have added a Bluetooth feature so that user can also connect to mobile and get the same data as shown on the display board.This project is nice for those hobbyist with a little knowledge of arduino and sensors.This will help in future projects taking this as a reference.

Now some tips-You can solder the components if you wish but solder the sensor with care, after the setup is complete, take your phone open the S2 terminal for bluetooth app(download from playstore, link-,pair the bluetooth module HC05 with 0000 or 1234 pass(if you are using the bluetooth module first time),and then get your data. Now while attaching the bluetooth module attach a voltage divider at the Arduino TX and HC05 RX portion to convert 5V to 3.3V (dont worry-circuit is there in fritzing file), while uploading the code,always remove the RX and TX lines and after uploading, reinsert it. You must download the two libraries- DHT library and LiquidCrystal library before uploading the code. Download from Github,extract and paste the libraries in the Arduino->libraries folder. Adjust the potentiometer for your appropriate display for the 16*2 board.

So now go ahead and build!!!

Step 1: Parts List

1 Arduino UNO/Nano /Mega/Micro

2 DHT22/DHT11

3 16*2 LCD

4 HC05 bluetooth module

5 wires

6 10k resistor 1pc

7 10k potentiometer 1pc

8 breadboard /solder kits

9 2.2Kohm 1pc

10 4.7Kohm 1pc

Step 2: Making the Circuit

Download the fritzing file and do the connections as done.

Step 3: Uploading Code

After connections it will look somehow as this one.While uploading make sure you have the RX and TX lines of BT module and arduino are disconnected.After uploading reinsert the RX TX lines.

Step 4: Using Bluetooth

You will see your temperature and humidity as this one above. Now take your phone and download S2 termianl for Bluetooth Now pair the module with either 1234 or 0000 as pass. After pairing .open the app and you will see your data simultaneously on the mobile and 16*2 display

Step 5: Finally

So now keep this circuit in your room and enjoy your data!!!