So I've researched this topic a lot online, but haven't found what I'm looking for. Before I tell you this, I'll give you guys an idea of what I'm trying to accomplish. Please understand that I'm an extreme beginner to Arduino, and that I've only been at this for a month or so, but plan on doing so much more.

My friend and I are building an RC car. We have an Android phone that has a downloadable application which connects to the Bluetooth HC-06 module that is on the Arduino UNO. We have configured our circuit, and it works fine! I want to go a step above and beyond, though.

My goal is to build a physical, handheld controller or remote (literally plopping everything on a breadboard), and connect that controller or remote to our car using Bluetooth. We have an HC-05 and HC-06 module, and the HC-06 is on the car. Now comes the doubt.

I understand how the android application sends characters through to the RC Car via Bluetooth; that's pretty straightforward as the two pieces are paired (using Android's Bluetooth Settings). What I don't understand is how to pair the two HC-05 and HC-06 Bluetooth modules. There isn't too much help online, I feel. I've looked and people have shown that they connect, but they don't explain the theory, so to speak.

What I want to understand is:

  1. How the two HC-05 and HC-06 modules pair, and
  2. How can I read input from one (remote controller) and execute an action on the other (RC car). From the app-to-Arduino, I was using Serial.available() to see if the Serial had any characters sent over from the application. I can't see how I can do that with HC-05 to HC-06 pairing, however. This concept is hard for me to grasp.

Any help is greatly appreciated. Thank you!

3 Answers 3


You need to set HC-05 to master, and this done by soldering pin 34 of BT and connecting it to digital pin on Arduino to enter AT command. Then after powering the Arduino, you need to put pin 34 high. This way it will enter AT command. In serial monitor, follow these AT commands:

AT+LINK= ????,??,??????  // REPLACE ?... WITH HC-06 MAC ADDR 
  1. Have a look at this for how to pair them http://www.martyncurrey.com/connecting-2-arduinos-by-bluetooth-using-a-hc-05-and-a-hc-06-pair-bind-and-link basically you need to use the AT mode.

  2. As far as I know you will be using the serial connection to communicate, but if you are using UNOs debugging becomes a bit more difficult, because you can't use serial for debugging.


For this you just have to pair the both bluetooth modules with each other.! For this use AT commands.

You can find those here: https://www.rcscomponents.kiev.ua/datasheets/hc_hc-05-user-instructions-bluetooth.pdf.

For pairing use MAC address of one module and hardcode it in second module using AT commands. Now from theory point of view for pairing between any two bluetooth modules,there are some handshaking signals which are processed and if they are correctly processed then the device gets paired. Its very hard to debug. But for that purpose use software serial

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