How does the S130 do scheduling for the radio?

[Marius Heil]

Hello,

when using the S130 with multiple connections and sporadic advertisement and scan procedures, I get a connection timeout after a few minutes, now I must know, how these events are scheduled internally. I think that connection events should be preferred in most cases, though it might be possible to skip one or two, when slave latency is enabled. As far as I know, the device must reschedule at times to meet the new requirements that are sent by the master (a connection event offset for example). When this is done, this might collide with the advertisement schedule. Will the advertisement schedule be shifted in this case? I hope I could get some insight on this because I am a little in the dark because there is no API to find out any of this, the problem is that I do not have any measuring equipment as well, which makes it hard to find out why connections were lost. I have a connection interval of 30 milliseconds at the moment and a connection supervision time of 4000 milliseconds, so i would not expect that a connection gets lost.

Thanks, Marius

[Asbjørn]

I would recommend you to have a look in the S130 softdevice specification is you haven't done so already: www.nordicsemi.com/.../53267556

Advertisements might be put aside if it collides with connection events. How many links do you have running at 30 ms? What happens if you reduce the connection intervals?

[Asbjørn]

May I ask you to have a look at the nRF Sniffer and the user guide for it. This could be used as a tool to see which package that are lost and from which end they are lost. I would try to increment the connection interval as well as it seems like you run into this issue faster with a shorter connection interval. It would be interesting to see the sniffer trace of what happens in your setup when this occurs.

Please also see the limitations stated in the S130 release note:

• The scanner can skip scan intervals if the scan window and the scan interval are of the same or similar size (DRGN-5013).
• After sending a connection parameter update, the radio events for the updated link may block scheduled events for other links or flash operations (DRGN-5151).