I would like to have control over the connection interval in order to optimize power consumption of the device. When I connect the SAMB11 Xplained Pro to my Android phone, the connection interval is 48 ms. Then I send at_ble_connection_param_update() and the phone seems to choose the con_int_max. It even seems to be OK to set con_int_min the same.
So it worked as I wanted, but not with my old iPAD (I don't know which model, maybe 4 years old, IOS 8.3). It just send AT_BLE_CONN_PARAM_UPDATE_DONE with all parametes zeros and kept on with the stupid 30 ms connection interval consuming 500 uA instead of 30 uA.
Is this to be expected on many BLE devices, mainly handheld? How can I make a system, that would consume ~50 uA? Only way to keep it just a broadcaster? But then I can't get any data from the user.