Channel bandwidth allocation method

[zjj]

hi，

I want to know how Bluetooth allocates channel resources as a master.

Assuming a Bluetooth master is connected to 8 slaves simultaneously, how does the master allocate communication time with each slave?

If multiple slaves send messages to the master simultaneously, will it result in most of the slaves' transmissions failing due to conflicts?

Can I specify priority for receiving messages from a particular slave?

[tesc]

Hi,

In Bluetooth Low Energy (BLE) terminology, devices in a connection are either Central or Peripheral. The timing of the link is controlled by the Central. If a Central has multiple connection to Peripherals, it typically attempts to schedule the connection in such a way that there is minimal overlap.

Connection parameters for a BLE connection is decided by the Central only, and the only choice of the Peripheral is to either accept the parameters or disconnect.

For details on how our BLE controller works, both with regards to priorities when connection events collide and with regards to connection timing as a Central, please see the Timing-activities and priorities section of the SoftDevice Controller documentation.

In the case of a central, the connections will be scheduled such that links do not collide (if possible), or if a non-colliding schedule is impossible the links will typically be run in a round-robin fashion.

Regards,
Terje

[zjj]

Thank you, tesc

And my other question is whether a Central device can simultaneously send or receive data on different channels?

[tesc]

Hi,

Any device (both central and peripheral) can be in multiple concurrent connections. However only one channel is used at any instance in time, and for one connection only.

A BLE connection consists of connection events, which are shorts bursts where packets are sent back and forth between central and peripheral. If the connection events of two connections overlap, then only one of the connections will get their event handled on the device.

Regards,
Terje

[zjj]

I got it, thank you.

[zjj]

hi，If a Bluetooth central device is connected to five peripheral devices simultaneously, is there a way to control the central device to only poll two of the peripheral devices at a time, while the remaining three peripheral devices only need to send messages at the lowest frequency to maintain the connection?

Is it possible to control the timing of connection events between the central device and the peripheral device?

[Kenneth]

Hello,

The central device should be able to control connection parameters, e.g. connection interval and slave latency for each link, so it should be possible for the central to do this yes. The peripherals will follow whatever the central chooses, though be aware that changing connection parameters usually will take 6+ intervals before they take effect.

Kenneth