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Do current BLE modules support v4.1 or 4.2 of Bluetooth?

Tester Testov

I'm a new at BLE. So, as I know from bluetooth spec v 4.1 there is a opportunity to establish multiple connections to the same peripheral device from several central devices. Does any Nordic BLE module support this functionality? What vendors does this function support?

  • 0

    Hi

    Nordic's latest BLE protocol stacks (the SoftDevices) support BLE V4.2. The SoftDevice S132 is for nRF52 and the S130 is for nRF51. If you have a look at the Multilink scheduling chapters you will find that the S13x SoftDevices supports

    "...up to three connections as a central, up to one connection as a peripheral, an advertiser or broadcaster and an Observer or Scanner simultaneously."

  • 0 in reply to MartinBL

    Thanks for your answer! But one thing is not so clear.

    "...up to three connections as a central, up to one connection as a peripheral, an advertiser or broadcaster and an Observer or Scanner simultaneously."

    But what if I want to have only 3 peripheral connection simultaneously and no one from others types. Is it possible? I mean can I connect to one peripheral device from several central devices? To correspond to this condition

    • A peripheral can be connected to multiple centrals.
  • 0 in reply to MartinBL

    It's ok but nevertheless there is described that multiple peripheral connections are possible. So, it's possible and it works but there are different networks. Is it right?

  • 0

    Hi Tester Testov,

    You are correct that it is possible for a peripheral to be connected to N number of devices and there is no limit except for the time it takes to maintain all the connections. The only limitation is the clock drift of the master/central that might make the listening window of the peripheral collide with other masters, thus it would be hard to maintain the connection. One way of working around this problem would be to have support for LL_CONNECTION_PARAM_REQ.

    Regarding the network part of your question: I assume that you mean that the centrals connected to the peripheral cannot talk to each other, and this assumption is correct. The only way they could talk to each other is if the peripheral was configured to relay the packets it received.

    If you would like to read a bit more about LE topology, you can have a look in Core Bluetooth 4.2 spec Volume 1, Part A, 4.1.2.

    In the drawing there there is just one mode that our SoftDevices does not suppoert yet, and that is having two connections in the mode of a peripheral (Device O is connected to two centrals and is initiating a connection to a third device). (Having two centrals connecting to us) There might be other vendors out there that support this mode currently. We might release a SoftDevice with this functionality in the future, when is something that I don't know.

    With the latest softdevice, released two days ago (s130 and s132 v2.0.0) we added configurable support for up to 8 central connections or 7 central and 1 peripheral connection, plus simultaneous broadcasting and scanning. You can also configure it to have 0 connection to save ram and only do scanning and broadcasting.

    BR Pål

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