How to connect Bluetooth HC-05 or HC-06 module with Nodemcu Esp8266-12E WiFi module

Nodemcu is a WiFi module and is popular among hobbyist for building DIY home projects. In some projects/applications Bluetooth is required to be connected to nodemcu. For example recently i was working on a project in which a DIY washing machine is delivering status of cloths after every 2 minutes to Bluetooth device. One can easily see the status of machine on a Bluetooth app. I decided why not to see the status in a browser and also list down the history. I connected a Bluetooth device and SD card with nodemcu. Bluetooth receives the status of machine and saves it in the SD card. Nodemcu is working as a server, serving a web page. When ever a client made a request to server, nodemcu fetches the saved data from SD card, lists down the history on a web page and servers it to client. It was a big project I am going to share only a small part of it in this tutorial on how to connect Bluetooth module HC-05 and HC-06 with nodemcu.

HC-05 and HC-06 Bluetooth module

Difference among the two modules can be many but the only ones that are serious to be considered before choosing them for a DIY project are

Hc-05 can work as master and slave. It can initiate pairing request to others and other devices can also request it for paring.
Hc-06 Module can only work in slave mode. It can not initiate pairing request to other nearby devices. It can only accept the pairing request made my others.
Hc-05 module has some extra pins which can be used as GPIO.

Both the Hc-05 and Hc-06 modules works on 3.3v TTL level signal. Input supply can be between 3.3 to 6 volt. On board regulator converts the voltage suitable for the Bluetooth module to operate constantly. Hc-05 and Hc-06 communicates with external controller on UART interface.

Nodemcu also works on 3.3v TTL level signal. Module can be powered by 5 volt source. Its on board regulator also levels down the input voltage to 3.3 volt. UART interface of both the modules can directly be connected, since both the modules are working on same 3.3v TTL level signal. No pull up or pull down circuit is required. Pull up down network is required when modules are working on different TTL levels like 3.3v and 5v. Connect directly Tx of nodemcu to Rx of Hc-05 and Rx of nodemcu to Tx of Hc-05. Circuit diagram of the project is given below.

Hc-05 and Hc-06 Bluetooth Module with nodemcu

Hc-05 or Hc-06 module can directly be powered by nodemcu Esp8266-12E WiFi board. Nodemcu 3.3 volt output provide enough current on which Bluetooth module can be operated.

Android App – Bluetooth Terminal

I downloaded a simple app from play store for this project. The app can easily locate and pair with near by Bluetooth devices. You can download the app by Clicking Here.

The code is simple. It is written and compiled in arduino ide. Just upload the code to nodemcu. Make sure to select the right board. After uploading open serial monitor of arduino Ide.

Hc-05 Hc-06 Paring with android app

Power the nodemcu and Bluetooth module. Open the android app and scan for available networks. You can see HC-05 or HC-06 in available devices depending on the module you are using. Select your Bluetooth device, a window will pop up asking for password. Default password for HC-05 and HC-06 module is 0000 or 1234. Enter it and your mobile will be paired with the Bluetooth module. Default communication baud rate of app is set to 9600 bps. At nodemcu side we set the communication speed to 9600 bps hence we do not need to change any settings on the app side. Now enter your message in the app and send it. Your message will be displayed on the serial monitor of arduino.

Arduino serial monitor received data

Android app scanning available devices

I showed in this tutorial how to effectively communicate between Hc-05, Hc-06 and nodemcu WiFi module. Project can be further extended. On receiving data multiple triggers can be generated for example bulb on, fan start, water pump start etc.

Download the project code. Folder contains project .ino file. Please provide us with your feed back on the project. If you have any questions or queries feel free to write them in the comments section below.

Bluetooth with Nodemcu.ino