Maximum number of BLE slaves with RPi Master

RE: Maximum number of BLE slaves with RPi Master

awneil — Fri, 02 Nov 2018 11:17:10 GMT

[quote userid="6462" url="~/f/nordic-q-a/39998/maximum-number-of-ble-slaves-with-rpi-master/155534"]the S132 and S140 Soft Devices support 20 links - thus, the nRF52 chips can support 20 links[/quote]

Well, look what's just popped up on Twitter:

twitter.com/.../1058253531189194755

RE: Maximum number of BLE slaves with RPi Master

awneil — Thu, 01 Nov 2018 10:39:17 GMT

[quote userid="25682" url="~/f/nordic-q-a/39998/maximum-number-of-ble-slaves-with-rpi-master/155522"]I do not believe it is a good idea to somehow try to flash the S132 or S140 softdevice on the Raspberry Pi Bluetooth chip (if that is what you were hinting at, awneil). [/quote]

Indeed not!

I was just pointing out that the S132 and S140 Soft Devices support 20 links - thus, the nRF52 chips can support 20 links.

Sorry if that wasn't clear!

This demo showed a Linux-based "host" (a mangOH Green) talking to an nRF52832 Central to control multiple BLE Peripherals - in this case, using a UART link.:

https://twitter.com/antronicsltd/status/1002872850699743232

Presumably, if you did want the code on the RPi, you would use the BLE Serialisation?

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.2.0/lib_serialization.html?cp=4_0_0_3_42

devzone.nordicsemi.com/.../serialization-support-and-examples

RE: Maximum number of BLE slaves with RPi Master

Bjørn Kvaale — Thu, 01 Nov 2018 10:03:34 GMT

[quote user=""]Using any of the nRF52 products, would it be possible to connect, say, 20 devices to the RPi?[/quote]

You could attach a 52840 dongle to the Raspberry Pi & run the v6.1 S140 softdevice, along with the multilink example. You could then use the HCI interface to communicate between the dongle & the RPi. You would most likely need to develop some small application on the Rpi to pick up all of the Bluetooth packets from the different sensors/actuators. These two links may also be helpful: link 1, link 2.

Update: This link might also be helpful.

I do not believe it is a good idea to somehow try to flash the S132 or S140 softdevice on the Raspberry Pi Bluetooth chip (if that is what you were hinting at, awneil).

[quote user=""]Does this have much to do with running a BLE v4.x vs BLE v5.x? I.e. does the new Bluetooth v5 specification change things in this regard?[/quote]

Like awneil said, nope. The S132 & S140 softdevices can run 20 links on either v4.2 or v5.

[quote user=""] Do nRF52s running BLE allow for parked slaves? I know this was a feature in classic bluetooth, and since the communications requirements are so low, I am thinking that slaves could go round in order taking turns to be "active".[/quote]

You can put a node to sleep & wake it up occasionally, yes. See the documentation here for more info.

RE: Maximum number of BLE slaves with RPi Master

awneil — Tue, 30 Oct 2018 16:45:48 GMT

Could you not use the built-in Bluetooth on RPi 3 ?

The S132 SoftDevice v6.1 supports up to 20 connections: http://infocenter.nordicsemi.com/pdf/S132_SDS_v6.1.pdf - page 11.

So does S140: http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.softdevices52/dita/softdevices/s140/s140.html?cp=2_3_2

[quote userid="74371" url="~/f/nordic-q-a/39998/maximum-number-of-ble-slaves-with-rpi-master"]Does this have much to do with running a BLE v4.x vs BLE v5.x? [/quote]

No.