How to create a bluetooth module that is both a master and slave

audiobluetooth

I'm working on a project that involves having a bluetooth module be a master and slave. I am a dummy when it comes to these things.

Basically i need one device like an iPhone to be able to communicate to two bluetooth speakers. But the bluetooth speakers need to be able to speak to each other.

Best Answer

It all comes down to what different micros support. Take a look at the PSOC4, which comes in BLE and Bluetooth classic. The choice comes down to whether or not you are trying to get audio back and forth between the speakers or just a little general info. For audio, do not use BLE as the throughput will not be high enough for you. Though on that same not Bluetooth classic may have some noticeable latency.

That said, the part has a very nice command for you which allows you to switch back and forth between slave and master, so you should be able to accomplish what you need based on switching back and forth on a timer or when a given flag is set. Getting smart on the timing will allow you to bypass the need for being in both at once. Hopefully this is what you were looking for.

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EGBT-045MS and EGBT-046S are generic Bluetooth Modules loaded with SPP ﬁrmware for UART wireless cable replacement functions. The EGBT-045MS can be conﬁgured by the user to work either as a master or slave Bluetooth device using a set of AT commands.

the S means just slave.

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I explain the way to do it on this blog post or in great details on this Instructables. For now, here is the basic code that you can put on the master device and the slave device.

//Master code
void setup() {
  Serial.begin(115200);
  Serial.print("$$$");
  delay(100);
  Serial.println("SM,1");  delay(100);
  Serial.println("C,000666123ABC");
  delay(100);
  Serial.println("---");
}

//Slave code
void setup() {
  Serial.begin(115200);
  Serial.print("$$$");
  delay(100);
  Serial.println("SM,0");
  delay(100);
  Serial.println("---");
}

And some tips before you go further with Bluesmirf:

Read the User Manual
Serial speed: By default, BlueSmirf is set to 115200 so you need to call Serial.begin(115200); before sending the first command.
The "$$$" command is the only one that is not followed by a carriage return. Why? To complicate things of course. Use print() for the "$$$" command and println() for all other commands.
Read and validate all the responses that are sent back.
Wait 100ms delay after each command you send and before trying to read the response. This will give Bluesmirf the time to process the command.
Don't forget to exit the command mode (using “---”). Some commands are not effective until you have exited the command mode (e.g. MS command).

Best Answer

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