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Or is there any other trick to do it?

I need to change a baud rate of my Bluetooth module, I have tried it via Windows Bluetooth settings of the particular Bluetooth device, but that doesn't work.

I am using Bluetooth serial terminal Windows 8 program to send and receive data from the Bluetooth device. The data sent match only if Oscilloscope baud rate is 9600. I want it to work with 2400.

Any idea?

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  • \$\begingroup\$ which module you use? \$\endgroup\$ – user76920 Jun 8 '15 at 10:39
  • \$\begingroup\$ It seems it doesn't have a reference, or at least it has not been provided to me: aliexpress.com/snapshot/6637896854.html?orderId=67024967214998 \$\endgroup\$ – Ondrej Tokar Jun 8 '15 at 10:47
  • \$\begingroup\$ See my answer for manual. Please accept Master Yoda's answer as it is correct and should work (as the manual confirms) \$\endgroup\$ – Russell McMahon Jun 9 '15 at 9:05
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Based on what you wrote, it's not enough for anyone to give you a good answer, but I'll try to. You need to find module user manual, almost every serial communication based device such as GSM/Bluetooth module is using AT commands, ofcourse it all depends on module and firmware. So there are commands to change baud rates such as

For 2400 baud you'd use:

      AT+BAUD2

Generally you use AT+BAUDn

where N = 1, 2, 3, 4, 5 ... for 1200 / 2400 / 4800 / 9600 / 19200 ... baud

>     Change the Baudrate
>     
>     The example below shows how to set the baudrate to 4800 bps
>     
>     Send the command (case sensitive!)
>     
>     AT+BAUD3
>     
>     the Bluetooth will reply:
>     
>     OK4800

Read this article

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  • \$\begingroup\$ I agree - this is valid - although I have never found a (cheap) module that wouldn't just ignore this command \$\endgroup\$ – CL22 Jun 8 '15 at 10:53
  • \$\begingroup\$ See my answer ... \$\endgroup\$ – Russell McMahon Jun 9 '15 at 9:05
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I've been playing around with such modules for years. I have at least 10 of them because I use them so much, and have often wanted a faster speed. Sadly I have been unable. They all make use of a USB chip which is programmable, but it gets very technical. There is certainly no way to do it through windows or the serial interface. Saying that, I've been buying cheapo modules from eBay - probably 5 or 6 different types. I know there are modules where you can configure the baud rate, but they are far more expensive - I believe the cheap modules were designed for a specific purpose which never got used in the product they were designed for.

I suggest you look at datasheets for all the chips on the module, and see which are programmable, and how they can be programmed. It may not be possible without de-soldering the chip(s) from the modules and programming them using the development kits and/or programmers.

For cheap options, you might want to look at bluetooth modules which are designed for faster digital data such as audio - but then they will not register as serial data dongles from the USB side, so you may have to jump through hoops on the PC side to make a software adaptor that hi-jacks the audio and makes it available as serial data.

The modules I've bought tend to have a baud anywhere between 1200 and 9600, so if you pick up a few of them, you might get one that is at the lower baud you want. But at that point, you might as well buy one from a decent source where they guarantee the baud is configurable (and has instructions on how to do so).

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  • \$\begingroup\$ See my answer and liked manual. May be some value there. Or not :-) \$\endgroup\$ – Russell McMahon Jun 9 '15 at 9:06
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@Master Yoda's answer is technically complete correct
AND there is a data sheet available for your module
AND it does say that Master Yoda's answer should work.
Accept his answer :-) - and look at the data sheet

The data sheet can be found here

I found the data sheet by going from the ad you cited to the store using the "Visit Store" button, then going to the on-site ad for the product and there it was. This is not usual, but no complaints :-)

The relevant portion from the data sheet says:

enter image description here

NB in their example they include spaces either side of the "+". This is not what the manual says and should not be correct BUT if the 'correct' version does not work try adding spaces.

You will have to use 9600 baud to set this

Their example

Example: Send: AT + BAUD6
Returns: + BAUD = 6
At this baud rate to 38400

Note: After baud rate change, if not the default of 9600, when after the parameter settings or data communication, use baud rate settings.)

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