Reviews – HC-05 Bluetooth Module

The HC-05 Bluetooth module is the most economical and easiest way to go wireless (via Bluetooth).

This module makes it easy for you to wirelessly extend your serial interface, so you can control any program running on your Laptop with serial port interface.


The 4 pins are:

  • VCC (Power 3.3 – 6V);
  • GND;
  • TXD;
  • RXD;

Default pairing code: 1234

Default baudrate: 9600

Usually this Bluetooth module is used with the Arduino, but it can be used with others microcontrollers devices. Here it’s how it’s wired with an Arduino:


So if you’re looking for a good way to communicate to your Arduino trough bluetooth this is a good way. I’ve already made a tutorial using this particular one and I’ll be doing more and the internet is full of tutorials using this exact model.

I’m not selling any product, but I do earn a small commission If you buy the item trough my links. You don’t pay more for the product or anything that’s just the way amazon does their advertisement. I’m not responsible for any problem with the product or anything I’m just telling what I really think about it. I would really appreciate if you use the links to buy. This is a way you can help me a bit improve my tutorials.

Thanks for reading, you can contact me by leaving a comment. If you like this post probably you might like my next ones, so please support me by subscribing my blog and my Facebook Page.

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39 thoughts on “Reviews – HC-05 Bluetooth Module”

  1. Any plan on an app in Processing(Android) to send/recieve data to arduino instead of bterm?
    I find it hard to figure out how to setup bluetooth commuication from tablet to arduino so any help would be highly appreciated.
    I followed your guide and made a fine working setup so i can control a minirobot from my nexus tablet. But only via BTerm.
    I would like to use my own Android App, but the communucation is really killing me. All the guides I have found requires a high programming skill level, og using Eclipse(that I find hard to deal with).



  2. Hi,
    Thanks for trying my project and taking the time to comment my blog! I really appreciate.
    I don’t know any app that is easy to work with on android and arduino besides blueterm app…
    I know exactly what you mean. I’m trying to make an android Bluetooth app but i don’t know much about android programming. and that’s why is taking me so long. besides there’s just a few projects around that so i think i won’t be able to finish that idea in a near future 🙁
    But If I find a way I’ll definitely post here my project!

    • Thanks so much for your feedback!
      I hope you see my next projects coming out this weekend.
      Subscribe to my newsletter and youtube channel so you don’t miss anything.

      Thanks again,
      Rui Santos

  3. Hi. I’m having a project using HC-05, Arduino UNO, and an android application. When I’m going to connect my application to HC-05 BT Module it will only be paired with the password “1234” but its status is “Paired but not connected”. How is it possible Sir?

    I already eliminated other devices which I paired and connect before but still nothing happened.

    • Hi Castilho,
      You need to pair first. ans as you said it says paired.
      That’s a good sign.
      Only after that you must connect your device to the bluetooth module.
      First pair then connect.

      • Thanks for the quick reply Sir. Yup, its already paired. I tried to connect my phone to HC-05 and I tried also connecting HC-05 using a lot of android applications but still nothing happened sir.

        When the HC-05 was “paired but not connected” the blinking is still there but in a longer interval instead of steady. Could it be a problem with the HC-05 itself? How can we solve it sir?

        • With which applications are you trying to connect to?

          I think you’re HC-05 is completely fine… but it might be some problem
          with your smartphone or with apps you’re trying to do that.

          Can you try with another android phone?

          • I already tried the bluetooth_for_arduino MIT App, Bluetooth Chat, RemoteBluetooth, and ArduDroid by TechBitar. All of those apps can’t connect with my HC-05 sir. I tried already using Cloudphone, MyPhone, and a Tablet. Still, its just the same.

            This problem is about a month now.

          • Seems to me that you’ve tried everything.
            I have no idea of what’s the problem seems that you’ve made everything properly…
            It’s impossible for me to know what’s happening.
            I know that my app should work for you the other ones I’ve never used it myself.

            Try with another android smartphone.if you face the same problem.
            try to find a friend with a bluetooth module and try to connect with your smartphone.
            Otherwise you might need to get a new bluetooth module I guess.

  4. I am using Arduino uno r3,and Bluotooth Module hc-05.BT Hc-05 is connected to Arduino.I have this Bluetooth connection Problem I tries Doing this: result is that When I used the Tera Term with USB Cable connected to my Arduino everything works fine,but When I Unplug the cable and used the 9v supply and Run The Tera Term,the console of Tera term is so empty no sign of output.Considering I Already Paired my Laptop and The Bluetooth module they are really paired.Do you Know What to do?

    • Hi Nathalie thanks for contacting me.
      I’m not sure if this is the problem.
      but from my knowledge I think the 9V battery can’t supply the bluetooth module
      it can have enough Volts
      but it might new a few more A (amps)
      if there’s not enough current your bluetooth module won’t work properly
      I hope this helps.

  5. Hi. I think an android emulator (e.g.MIT app inventor emulator) on my PC can also communicate with the arduino through this Bluetooth device isn’t it? I don’t have an android phone but i just wanna control arduino on my PC

  6. Hi! I have HC-05 Bluetooth Module, but I want to simulate it’s work.
    I use always Proteus for simulation, still I can’t find Bluetooth Module in the library. Is there maybe any other program? Or something special for Arduino?

    Thanks In Advance!

    • I’ve never used Proteus or any other simulation tool for the Arduino…
      So I’m not sure which software has a bluetooth library…

    • There’s no schematic for this project.
      This is just a product review of the bluetooth module. where I show some of the features and how it works…

  7. Have any ideas on how to make the HC-05 automatically connect to a cellular device? I have my phone pairing with the HC-05, but I have to physically connect with to it with an app.

    I’m wanting to be able to walk up to a door, have the HC-05 automatically connect to my phone, and then unlock the door.

    • I think you need to write your own app for android so it can handle that feature… because by default I don’t think that’s an out of the box solution…

  8. Hi
    I am working on a project that involves making use of a bluetooth. But I am confused between HC 05 and RN42 I/RM module. Can anyone tell me which one I should go ahead with? Since I am designing a product I would want the module to be efficient and at the same time easily programmable.

  9. Hi Rui, I like your projects very much 🙂 . Recently I’ve bought an HC-05 module to work with arduino, android and lcd. I wrote a simple program to receive string from my android phone using bluetooth and print it directly on the 16×2 lcd. Everything works fine as long as the arduino is powered from my PC. As soon as I disconnect from PC and power externally (even through USB), it won’t work. Every time I send something…some erroneous characters comes up on the lcd. Can you help me out?

  10. what is the difference betweeen hc-05 4 pin and hc-05 5 pin??can we use hc 05 5 pin instead of 4-pin which you used?
    and how hc-05 module different from hc-06 module?

  11. I tried your Amazon link, in your “Reviews – HC-05 Bluetooth Module”.
    It took me to an Amazon page for an HC-06 module.
    What is the difference between the HC-05 and the HC-06?


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