Why does central scan 2x longer when receiving advertisements?

[JB21]

using nRf52832 with S132 in central mode Scan-Interval= 3000 ms Scan-Window= 25 ms

Monitoring the current consumption I see a 25ms wide pulse, as expected. No advertiser is nearby, so no signal is received.

But as soon as an advertiser signal is being received, the current pulse width doubles to ~50 ms, even when it is not our expected advertiser. So any other BTLE advertiser nearby will cause draining the battery twice as fast. How can this be prevented? Why does the scanner listen longer? It should have gotten the advertisement already in the 25ms window.

Note: Our advertiser (other device) uses Adv-Interval= 20ms That ensures that the scanner never misses an advertisement.

[JB21]

Just realized that I fooled myself.

During debugging I used a LED flash during each rcv'ed advertisement, and forgot removing that part of code. Now that "problem" is gone.

But measuring more carefully, the curent pulse width is 40ms wide, not the expected 25ms.

Any idea why?

[Petter Myhre]

So you didn't see a 25ms wide pulse earlier? But 40? How are you measuring this? Could you edit your question and include a capture? There should be some radio startup and post-processing, as you can see here, but 15 ms sounds like a lot.

[JB21]

Petter, I measured again, and now the current pulse is 25ms wide, as expected. What was wrong the last time, I don't know. I worked on other parts of the code, perhaps new re-compilations made it happen? At least I'm glad that it now works as expected. Thank you for your effort.