Estimate CPU blocking time during connection

RE: Estimate CPU blocking time during connection

Hung Bui — Tue, 12 Jul 2016 10:29:25 GMT

@Revo: Do you have payload from the other side? Have you tried to test 6 packets per connection event from both sides (12 packets in total) ?

RE: Estimate CPU blocking time during connection

Revo — Mon, 11 Jul 2016 13:48:44 GMT

I will use this table as reference so, thanks. However i tried several minutes of data acquisition and i never lost samples, maybe because the beacon it's only sampling and sending, with no other services or i don't know.

RE: Estimate CPU blocking time during connection

Hung Bui — Mon, 11 Jul 2016 12:19:23 GMT

@Revo: If you have a look at the softdevice specification S110 v1.3 here At Table 30 in section 11.3.2 you can find that the maximum interrupt latency can be 5960uA. It's the worst case, so you may haven't experienced that ADC sampling is missing but there is no guarantee that the interrupt request can be handled shorter than 5960us.

RE: Estimate CPU blocking time during connection

Revo — Mon, 11 Jul 2016 12:13:36 GMT

No i know the limitations, but i already used it for my project (it's a unverisity, i have just the materials they give me ^^), i just wanted to justify this aspect of the blocking time. So you are saying that it's not possible to quantify it, just to know that it can goes up to 6 ms? Because i am sending 6 packets and sampling every 2 ms, and it doesnt' seems that i lose any data.

RE: Estimate CPU blocking time during connection

Hung Bui — Mon, 11 Jul 2016 11:54:36 GMT

@Revo: I would suggest you to get the new chip. The rev1 chip has a quite limited functionality regarding concurrent CPU and radio. This was fixed on rev3. Meaning the latency is reduced largely now. Have a look here.

If you use rev 1 chip, the CPU blocking time can go up to 6ms when having 6 packets per connection events.

RE: Estimate CPU blocking time during connection

Revo — Mon, 11 Jul 2016 11:09:29 GMT

I confirm the revision 1, the softdevice actually i didn't understand pretty well, it should be version 7, but it's the one in the latest firmware available on the page of the smart beacon kit of your site!

RE: Estimate CPU blocking time during connection

Hung Bui — Mon, 11 Jul 2016 10:13:06 GMT

@Revo: Could you provide more information about the chip revision and the softdevice S110 version ? You can find the chip revision based on this matrix.