CODEWITHSUNDEEP
bluetoothbluetooth-lowenergy
Ben Mosher
Ben Mosher

Reputation: 13381

Two centrals, one peripheral

Is it possible for a BTLE (4.0) peripheral to remain advertising after a central has connected, and could another central then also connect simultaneously?

I can find nothing addressing this clearly, while it is clear that a central can connect to n-many peripherals at once.

Upvotes: 6

Views: 2865

Answers (2)

Fabio Santana
Fabio Santana

Reputation: 31

The "Bluetooth specification Version 4.2 [Vol 3, Part C]" states the following aspects:

• Page 231: 2.2.2.3 Peripheral Role “Any device that accepts the establishment of an LE physical link using any of the connection establishment procedures as defined in Section 9 is referred to as being in the Peripheral role.”

• From section 9 at the "Limited Discoverable Mode" section at page 351: 9.2.3.2 Conditions "While a device is in the Peripheral role the device may support the limited discoverable mode. While a device is in the Broadcaster, Observer or Central role the device shall not support the limited discoverable mode." ... "While in the limited discoverable mode the device shall send advertising event types with the advertising data including the Flags AD type as defined in [Core Specification Supplement], Part A, Section 1.3 with all the following flags set as described" "The device shall remain in limited discoverable mode until a connection is established or the Host terminates the mode."

• From section 9 at the "General Discoverable Mode" section at page 352: 9.2.4.2 Conditions "While a device is in the Peripheral role the device may support the general discoverable mode. While a device is in the Broadcaster, Observer or Central role the device shall not support the general discoverable mode." ... "While in general discoverable mode the device shall send advertising events with the advertising data including the Flags AD data type as defined in [Core Specification Supplement], Part A, Section 1.3 with all the following flags set as described" ... "The device shall remain in general discoverable mode until a connection is established or the Host terminates the mode."

The standard is assertive you have to stop advertising when the connection is established.

Upvotes: 3

Will
Will

Reputation: 845

The Bluetooth Core Specification Version 4 says this on page 200:

"The Periph- eral role is optimized for devices that support a single connection and are less complex than central devices. Devices supporting the peripheral role only require Controllers that support the Controller’s slave role. The Central role supports multiple connections and is the initiator for all connections with devices in the peripheral role. Devices supporting the central role require a Controller that support the Controller’s master role and generally supports more complex functions compared to the other LE GAP roles."

Which looks like a no to me, but it's not quite as specific as you might have hoped.

You can find a list of the adopted Bluetooth specifications from bluetooth.com (formerly bluetooth.org) at this link:

https://www.bluetooth.com/specifications/adopted-specifications

The quote above comes from Core Version 4.0 page 200 and is also available in the Core Version 4.2 on page 98.

Upvotes: 6

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