For a project I am interested in using the HC-05 Bluetooth module to control five LEGO Mindstorms Bricks simultaneously. For this to work the Bluetooth module will obviously have to be paired / connected with the five bricks at the same time. This means that the HC-05 Bluetooth module will have to be master in the piconet and the five bricks the slaves.

Is there anyone who has any experience with using the Arduino Uno and HC-05 Bluetooth module to send data to multiple, connected, slaves? If not, are there any alternative Bluetooth modules? And if Bluetooth modules compatible with the Arduino Uno cannot connect to multiple slaves at the same time, are there other ways that an Arduino can control multiple Bluetooth slaves at the same time?

  • Would it be possible to have multiple slaves and talk to each of them individually? I don't need multiple simultaneous connections but one device talking to multiple and I have to be able to set which device it talks to when and what information is passed.
    – user26363
    Sep 5, 2016 at 0:25

1 Answer 1


After some research, it looks like multiple slaves aren't possible with this particular module.

According to Wikipedia the Bluetooth technology allows a master to communicate with 7 slaves, but this option isn't implemented in the HC-05.

  • I feared as much. Would you happen to know if there are any other Bluetooth modules or shields that support multiple slaves? Or that are worth looking into. Also, would you happen to know how long it takes for the HC-05 module to disconnect / connect to a Bluetooth device? Apr 10, 2015 at 9:12
  • No I never used any Bluetooth module so I can't help you, sorry. Google is still an option though. Apr 10, 2015 at 9:26
  • The connection/disconnection takes about 2/3 seconds to be achieved.
    – Stefa168
    Apr 10, 2015 at 12:11
  • Sadly that'd take too long for it to be practical. Apr 12, 2015 at 0:06

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