Connecting 2 Arduinos by Bluetooth using a HC-05 and a HC-06: Pair, Bind, and Link

In a previous post I showed how the HC-05 can auto connect to other Bluetooth devices by setting the HC-05 to pair with any device using CMODE=1. This is quick and easy but does not give any control over which other device the HC-05 connects to.

In this post I show how to set up the HC-05 to always connect to the same HC-06 (or HC-05 in Slave mode). For this we use PAIR, BIND, and LINK.

I am using 2 separate Arduino IDEs; version 1.6.3 which is installed, and version 1.0.5 which I run from a folder (it is the non install version). This allows me to use 2 IDEs at the same time, each connected to a different Arduino. It also gives me 2 serial monitors, one for each Arduino.

The modules used are the zs-040 versions of the HC-05 and the HC-06. The HC-05 has the Wavesen/HC firmware 2.0-20100601 and any any module running the same firmware will be the same.

The HC-05 has 2 AT command modes which I refer to as “mini” AT mode and “full” AT mode and some commands only work when in “full” AT mode. To enter “full” AT mode pin 34 needs to be HIGH and kept HIGH. To accomplish this I have made a connection from pin 34 to +3.3v. See the diagram below (or after the jump).

If you are not sure about At command mode take a look at Arduino with HC-05 (ZS-040) Bluetooth module – AT MODE

If you are not familiar with how the HC-06 and HC-05 work it may be worth while checking out some of the other posts:
HC-05 and HC-06 zs-040 Bluetooth modules
Arduino and HC-06 (ZS-040)
Arduino With HC-05 Bluetooth Module in Slave Mode
Connecting 2 Arduinos by Bluetooth using a HC-05 and a HC-06: Easy Method Using CMODE

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Connecting 2 Arduinos by Bluetooth using a HC-05 and a HC-06: Easy Method Using CMODE

Making a connection Between a HC-05 and a HC-06: Method 1

Using the CMODE command we have an easy way to connect the HC-05 and the HC-06 (or 2 HC05s). When the HC-O5 is configured to pair with any address (AT+CMODE=1) it should connect to a Slave module automatically. No binding etc is required.

I am using the zs-040 modules with firmware 2.0-20100601 and other modules with the same firmware will be the same. If you have issues check the data sheet for your module.

The Set Up

I am using 2 different Arduino IDEs; version 1.0.5 and version 1.6.3. This gives me 2 separate serial monitors. The Arduino connected to the HC-05 is on COM8 and the Arduino using the HC-06 is on COM17


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