Communication between two hc-05 Bluetooth modules

Set an hc-05 bluetooth module to master mode to send serial data to another module.

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If you've ever looked into controlling an Arduino remotely, then you've probably come across these HC-05 Bluetooth modules. Setting up serial communication from the computer is a simple task. But what if you want to use an Arduino or other microcontroller as the master?

Setting up communication between two modules is a two step process. The module to be used as the master must first be put into AT command mode in order to modify it's role as either a slave or master.

Slave role: The module waits for a master to connect to it.

Master role: The module sets up a connection with a nearby slave device and automagically builds the overhead for serial communication.

The default role on my modules was set to slave. Setting up serial communication was as easy as setting one of the modules to master.

Once you're in AT command mode, you might wish to change other features such as the devices name and passkey. Here's a link to a PDF with all the commands available.

Also, I highly recommend picking up an LCD Module that reads SPI for troubleshooting purposes. I've used mine countless times for many many projects.

NOTE: This project doesn't add much to Techbitar's excellent tutorial. It does offer a different method of accessing the AT command mode however.

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  • 1 × UART to Display Microcontroller to convert UART to lcd display; just for testing

  • 1
    Step 1

    Put the module to be used as master into AT command mode. If you have an Arduino handy, techbitar gave an excellent tutorial on how to do that here.

  • 2
    Step 2

    If you followed techbitars instructions, or already know how to do this, congrats! Skip ahead to step 11. Otherwise follow the next few instructions. You'll need to set up a serial connection with the module to be used as the master. What follows is just one method of accomplishing this.

  • 3
    Step 3

    If you bought two modules you'll be able to use the slave module to program the master. Connect the RXD of the slave to the TXD of the master and vice versa. 

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vonigohiy123 wrote 04/21/2016 at 09:39 point

what a good project..

please give code also.................

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