I have ordered my HC-05 BT modules. My question is this: Is it possible to send multiple channels over bluetooth. For example, stereo sound has two channels. I think i have seen people do this but i'm not sure.

If it is possible, could you please provide some more information on how its done? Thanks!

2 Answers 2


The BT module will connect as a SPP (serial port) device, and then pass the serial data to and from the arduino and whatever you choose to connect to (that supports SPP).

There is only one channel, and in any case only one set of TX and RX wires that will be connected to your arduino, but this does not stop you from sending as much data of as many different types as you want. You are only limited by the BAUD rate and how much time the message will take to send.

For complicated data transfers you will need to write the code for a protocol so both sides can make sense of what the other says. You are free to do whatever you can think of here, although if you need to make a complicated protocol you might get some use out of the answers to this question:

Communication Protocol Best Practices and Patters


To add to BrettM answer, Bluetooth is the RF standard on which many protocols can stack up; each such protocol is called a 'Bluetooth Profile'.

The Bluetooth model you purchased comes only with the Serial Port Profile (SPP) profile implemented in the firmware. This mean that you can use it for establishing serial communication.

As serial protocol will probably be too slow for stereo Audio over Bluetooth, Audio usually use a different profile called Advanced Audio Distribution Profile (A2DP). Unfortunately, the HC-05 does not come with this protocol stack implemented in its firmware. If your primary goal is to send stereo Audio over Bluetooth, consider purchasing a dedicated chip, such as XS3868 or Sparkfun's RN-52. For beginners, it is recommended to get one with a breakout board for easy integration with Arduino projects.

For completeness, there are many other Bluetooth profiles, each is optimized for different task. See Wikipedia for the full list: http://en.wikipedia.org/wiki/List_of_Bluetooth_profiles

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