Connection Parameters using nRF Dongle vs iOS

[BattleDroid]

SDK: 15.1
SoftDevice: S132, v6.1
IDE: Keil

Hello I am using the nRF dongle combined with nRF Connect on my PC to connect to my BLE peripheral (custom board).  During connected state, I am seeing my average current consumption change when I connect to my iPhone versus the dongle.  When I connect using the dongle Iavg = 125uA, when I connect using my iPhone Iavg = 100uA.

Q1.  What is going on here?  Is the dongle changing connection parameters on my peripheral device?  If yes, how can I modify it so that it behaves identical to iPhone?

Q2.  I ultimately want my peripheral device to connect to iOS or Android cell phone.  I am sending 10 bytes of data every minute, so very low throughput.  What are my limitations on increasing my connection interval before BLE connection is compromised?  I would like to understand the limitations of the peripheral, client, and throughput as they relate to these 2 connection parameters (MIN_CONN_INTERVAL, MAX_CONN_INTERVAL) .  Can you point me to some literature?

Thanks for your time

[Joakim Jakobsen]

Hi.

Q1:
It might be because the iPhone decides the connection parameters, thus increasing the power consumption if it changes. 

In that case you need to figure out what connection params the iPhone enforces and then use that when  with nRF Connect.

Q2:
The limitations of the connection parameters on our part is decided by the Softdevice. The limitations can be found in the documentation.
For general limitations for BLE, you can find that in the BT SIG - BLE Specification. I suggest that you take a look there.

Best regards,
Joakim

[BattleDroid]

Could you please elaborate on your responses?  I don't have enough detail to take action on my end.

Re Q1.  How do you determine the connection parameters the iPhone is using? Is there a menu in the mobile app that lets you see and/or modify these parameters?  Furthermore, how do you modify these in the nRF Connect PC app?

Re Q2.  The BLE specification is a rather large document.  Without diving into the entire document, is a there a section you can point me to with this information?

[Joakim Jakobsen]

Hi.

Sorry about the delayed response.

Since it is the central that actually decides the connection parameters in a BLE connection, the phone will decide the connection interval. I don't believe that neither Android or iOS devices provides any API or any other way to change this. What the peripheral can do is to request other connection intervals, but the central can decide whether to accept it or reject it.

The only thing the peripheral can do then is to disconnect (or accept the given connection interval).

Br,
Joakim