Max Connected Isochronous Streams (CIS) Supported in a Connected Isochronous Group (CIG) on nRF52840?

[Cintelex]

The Bluetooth Core Spec version 5.2 says that the "maximum number of CISes in a CIG shall be 31."

Can the nRF52840 support 31 concurrent CISes in one CIG? If not what is the max number supported, and what is the limiting factor?

[ovrebekk]

Hi 

We don't currently have a stack available with support for isochronous channels, which makes this question a bit hard to answer. 

I will check internally if it is known what this limitation will be in the future. 

Best regards
Torbjørn

[Cintelex]

Thanks ovrebekk. Looking at the Packetcraft Protocol Software, they say it implements BLE 5.2 isochronous channels and has been tested on the 

nRF52840 and nRF52832. I don't know how closely Nordic works with Packetcraft, but maybe they know whether there is a limit on the number of concurrent CISes supported in one CIG for these Nordic SoCs?

[ovrebekk]

Hi 

I had a talk with one of our stack developers, and he didn't know of any hard limit on this. Essentially it will depend on how much memory and CPU is required for each CIS, which is implementation dependent, so until we have a working implementation to benchmark we won't know for sure. 

Do you actually have a use case for 31 concurrent CISes, or is it more of a theoretical question?

When it comes to the Packetcraft implementation I suggest you discuss this with them directly, in case they have some performance data to share. 

Best regards
Torbjørn

[Cintelex]

Hi Torbjørn. Thank you for looking into it. Our application requires multiple bidirectional concurrent streams to support a conversation between individuals. 31 is more than enough, but <10 might be too few. I will discuss with Packetcraft to see if they have any insight. Thanks again, Chris.

[ovrebekk]

Hi Chris

Hopefully they have some data to share. Good luck with your project

Best regards
Torbjørn