Connection event position in time

RE: Connection event position in time

endnode — Tue, 23 May 2017 15:12:47 GMT

Yes, as I said there are certain way how to "shift" connection event (transmit window) after connection interval and I don't know how much Soft Device uses it (actually if this your question then formulate it like this in separate thread and Nordic team will answer it), however it has certain granularity so you cannot shift connection interval wherever you want + for long connections there is certain drift in the time so my bet is there will be collision sooner or later to solve. Are your concerns theoretical or you've really measured this? How it harms your application? (because it doesn't harm work of lower BLE layers)

RE: Connection event position in time

Andrzej Kuros — Tue, 23 May 2017 13:04:24 GMT

connection always starts with advertising packet - connection start is not an anchor point to connection events, look at transmitWindowOffset and Initiator timing? I suspect BLE specification predicted this case, but I don't know if s132 does anything about this.

RE: Connection event position in time

endnode — Tue, 23 May 2017 12:48:56 GMT

...this doesn't look like complete solution, once you have any GAP Peripheral connection you are more or less lost. In the end suppressing some events won't occur often (you can do some simulations and benchmarks yourself) so there should be no problem.

RE: Connection event position in time

endnode — Tue, 23 May 2017 12:47:38 GMT

I understand your fear but if you think it through there is no other solution to the problem: you have several asynchronous activities and only one radio, they will "meet" sooner or later and the only way how to deal with it is to make priorities and temporarily suppress some events. Luckily BLE thinks about such situations by design so it is not affecting reliability of the connection link, just throughput (logically;) You can try to minimize these overlaps by synchronizing the connection events but that won't really work because connection always starts with advertising packet and these are completely asynchronous (= random). There is small some limited space by choosing the same connection interval for all links (if you are GAP Central) and letting Soft Device to move first connection event of each connection to available "gap", then these should stay in sync. But overall...

RE: Connection event position in time

Andrzej Kuros — Tue, 23 May 2017 12:41:57 GMT

I suspect that according to scheduling when peripheral cennection events overlap with central connection events, the one which is first will suppress the later one. But I want to avoid this situation and move anchor point of connection such there would be no overlaps at all.

RE: Connection event position in time

endnode — Tue, 23 May 2017 11:20:02 GMT

Isn't that described in SD specification (Scheduling section)?