I'm having an ARM M3 which I would like to connect on one hand to a smart phone for data visualization and to two sensors for data acquisition on the other hand. Both connections should be BLE. My understanding is that this would require concurrent mode (central to peripheral), where peripheral is required to talk to the smart phone and central to talk to the sensors, correct?

I have a BLUENRG-132 from ST around but could find any information regarding concurrent mode. Is this normally supported by these devices or do I have to implement some kind of switching myself? Or isn't possible at all?


1 Answer 1


You are correct, in order to do this, your device would need to support the concurrent connections feature, also known as Dual Mode Topology. Dual Mode Topology is a relatively new feature in BLE that was introduced end of 2013. It requires both software and hardware support as follows:-

Hardware Support:- In order to support Dual mode topology, your device must be Bluetooth v4.1. This feature was added in Bluetooth v4.1 so Bluetooth v4.0 devices do not support it. More information on this is available in the Bluetooth specification v5.0, Vol 1, Part C, Section 7:- Changes from v4.0 to v4.1.

Software Support: In addition to the version of Bluetooth hardware, the stack/software must provide support for this feature. Not all Bluetooth 4.1 (or even Bluetooth 4.2 or Bluetooth 5) devices support this feature because the software vendor didn't expose it.

From this link, it looks like your device is 4.2, so theoretically the hardware capability is there. Also it is stated that one of the key features is "Master, slave, and multiple simultaneous roles", so the software supports it too. The details on how to configure this is found in this document in page 9.

I hope this helps.

  • \$\begingroup\$ Thanks, I already stumbled over these documents but wasn't sure the given information was really confirming what I was looking for. But is my assumption correct that the device would be a peripheral to the smart phone but a central to all the connected sensors? \$\endgroup\$
    – po.pe
    Commented Feb 4, 2019 at 7:55
  • \$\begingroup\$ Yes, seeing that your sensors will most likely be peripherals, your device has to be a central to them, and seeing that phones are better at being a central, your device will be a peripheral to it. \$\endgroup\$ Commented Feb 6, 2019 at 7:00

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