packets Loss in nRF51 & iOS streaming.

[Bayram ZAYET]

Hello NORDIC community,

I am performing a BLE throughput speed test via an example of streaming a buffer of 2500 bytes per second: This says a sending frequency of 19 Kbps.

I'm working on an iPhone 6s with a version of iOS: 10.3.2 Since the connection interval is 30ms (the minimum value supported by an iPhone). The sending and receiving frequency is 31 Kbps: for the value of 6 packets per connection interval. this stream should be working fine.

==> the result of my tests shows considerable losses !!!

I wanted to know if my problem results from my module nRF51 or the iPhone?

Am I missing a parameter in my calculations ?

If possible, is the number of packets per connection interval on an iPhone 6s with an iOS: 10.3.2 really 6 or less?

Thank you in advance for your reactivity.

Best Regards,

[Nguyen Hoan Hoang]

iPhone can work at 7.5ms, try min interval at 10ms see what happens

[Bayram ZAYET]

Thank you for your answer. But I believe that iPhone cannot work with less than 30ms refering to this link and others. Am I refering to wrong sources ?

[Nguyen Hoan Hoang]

Ok, I don't know where that 30ms limit comes from. I've worked with iPhone6 at 7.5ms (old SDK) and 10ms (new SDK14) and 10ms on Android. Anyway that is up to you.

[Bayram ZAYET]

Can I know how did you do that with iPhone? Because I think that iOS developers cannot set or modify neither connection interval nor number of packets per connection interval.

Regards,

[run_ar]

You should follow Apples bluetooth design guidelines. I have never seen an iOS device accepting connection intervals of 7.5ms. HID devices will be able to get down to 11.25ms. But I have usually ended up with 12.5 - 15. But seems like the spec has changed a little so you might be able to get 15 ms now.