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I am interested in working with BLE proximity sensor on iOS and have been looking up for a few answers to my query but could not find any solid ones.

1) Is there a maximum number of BLE slaves the CoreBluetooth can handle?

2) Will the slaves (about 10 devices) be able to be operated all at once i.e. if any slaves were to disconnect, master will be alerted while not affecting others?

Varun Mulloli
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Cheng
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1 Answers1

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Theoretically, there is no limit to the number of Bluetooth LE devices that can be connected to a single iOS device (if the iOS device is acting as central and the LE devices as peripherals).

In practice, however, the limit seems to be somewhere above 20 LE devices being connected simultaneously to the iOS master. That number comes from both Bluetooth LE transmitter manufacturers and accessory developers that I've talked to. The exact figure will probably vary based on the particular iOS device involved and the transmitting properties of the Bluetooth LE accessories.

Brad Larson
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  • Hi Brad thanks for the reply, but may i ask which manufacturers have you talked to? – Cheng Dec 15 '12 at 06:19
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    @Cheng - Bluegiga and an independent contractor building Bluetooth LE accessories. The people at Bluegiga are pretty open about the tests they've done with their hardware and iOS devices. – Brad Larson Dec 15 '12 at 17:28
  • What about Bluetooth 2.1 devices? – Van Du Tran Jun 28 '13 at 20:20
  • Bluetooth 2.1 seems to have a maximum of 7 slaves. – Sam Jan 28 '18 at 07:12
  • I have personally connect up to 12 BLE devices to my iPad, so that definitely works. Using RFDuino's. – Sam Jan 28 '18 at 07:13
  • @BradLarson, i have connected 14 HR sensors (Polar h10) , but my purpose is to serve 30 sensors. Could you please help me, how i can do this ? Any workaround ? – Jamshed Alam Sep 08 '20 at 06:42
  • I have seen many comments on the limits changing from hardware-to-hardware and iOS version-to-version. I have even witnessed this in my testing. Does anyone know if there are any official documents scribing these BLE concurrent device limitations? – pennstump Oct 01 '20 at 21:50