How does it work when ScanWindow == ScanInterval ?

RE: How does it work when ScanWindow == ScanInterval ?

is — Thu, 12 Jan 2017 15:20:26 GMT

I use s120 & nRF51.

RE: How does it work when ScanWindow == ScanInterval ?

run_ar — Thu, 12 Jan 2017 12:47:22 GMT

More details on scheduling can be found here. This is for the S132 though.

RE: How does it work when ScanWindow == ScanInterval ?

Nathan — Wed, 11 Jan 2017 22:01:30 GMT

Sorry, I missed that distinction in your question. Any time spent servicing an ongoing connection or advertising will be time when the device is not scanning (scanning is considered a lower priority). So free time is more accurate.

RE: How does it work when ScanWindow == ScanInterval ?

is — Wed, 11 Jan 2017 16:14:14 GMT

To switch frequency the nRF supplies 1ms after scan window ("scan reserved" gap in a s120 manual). But this does not explain how the nRF is able to keep several connections and sends data (there are no drops!) during the scanning.

RE: How does it work when ScanWindow == ScanInterval ?

Nathan — Wed, 11 Jan 2017 16:04:12 GMT

Adding as a comment because I don't have the hard number details, but BLE advertises on 3 separate advertising channels. The chip is not capable of scanning on all 3 simultaneously, so the scan interval sets the timing between when the device switches channels and begins a new scanning window on a new channel. There's a small delay time during the switch (the hard number I don't have on hand right now), but when you set window equal to interval, what happens is you're constantly scanning minus the channel switch time, and the interval time sets the timing between when channel changes take place. You won't catch any advertisements that get sent out on one of the other two channels at any given point in time, but usually advertisers quickly send a burst on all 3 anyway. Someone correct me for any inaccuracies please.