simultaneous advertising and scanning

RE: simultaneous advertising and scanning

haakonsh — Fri, 23 Mar 2018 13:42:39 GMT

Hey Matthew,

It definitely seems like one scan interval is ignored after an advertisment. I'll ask around the office what's up with that quirk.
I guess you will have to aim for a really short scan window and interval.

I'm off work during the Easter holidays,

Best regards,

Håkon

RE: simultaneous advertising and scanning

mregan11 — Thu, 22 Mar 2018 15:24:47 GMT

I tried using a scan window of 311.25ms, a scan interval of 318.75ms, and an advertising interval of 318.75ms. This results in periods of 318.75 where I am not scanning. This will not work. What is the best way to scan all the time except when I'm advertising?

I tried a scanning window of 20ms, a scanning interval of 20ms, and an advertising interval of 760ms. This results in periods of either 20ms or 40ms where I am not scanning.

Matthew

RE: simultaneous advertising and scanning

haakonsh — Thu, 22 Mar 2018 12:22:02 GMT

Try using a scan window of 330-7.5ms = ~322ms

RE: simultaneous advertising and scanning

mregan11 — Thu, 22 Mar 2018 11:07:53 GMT

Hakon,

My product works with an off the shelf wireless BLE switch. When the switch is pressed, 3 1ms advertisements are sent out, then 20ms lapse, 3 more 1ms advertisements are sent out, another 20ms lapses, then finally 3 more 1ms advertisements are sent out. It is recommended that I scan 23ms out of at least 33ms in order to ensure the best chance of receiving the switch advertisement. Right now, I am advertising only to support OTA updates. If I make a connection while I am advertising, I am no longer concerned with scanning and can stop scanning if I need to.

I recently tried a different approach where I scan for 10ms window and 10ms interval. I changed my advertising interval to 760ms. This seems to help. I thought that when advertising occurs that I would not scan for 10ms. However, using radio events it appears that I stop scanning for 2 scanning intervals, or 20ms, when I'm advertising.

This seems to be a better approach? Do you know of the mimimum scanning interval required such that only 1 scanning interval will be skipped when advertising?

Thanks,

Matthew

RE: simultaneous advertising and scanning

haakonsh — Thu, 22 Mar 2018 09:27:04 GMT

Hey Matthew,

The easiest option is to scan for shorter windows and intervals, thereby continually scanning.

Do you mind sharing some more details about your communication needs? I might be able to help you find a better solution.

Cheers,

Håkon.