nRF iOS App - disconnect unknown error

[hannes]

I'm running a fine working example based on the Bluetooth low energy Characteristics, a beginner's tutorial on the nRF52DK using SDK 15.3 working as a BLE peripheral.

When I connect to the peripheral via the nRF52840-Dongle or the Anroid App (ver 4.24.3) everything works fine and as expected. But when i connect to the peripheral via an iPhone 11 Pro Max running iOS 14.1 and nRF Connect iOS App ver 2.3.2. the devices disconnect after about one and a half minute.

The log in the App says:

- [Callback] centralManager (central, didDisconnectPeripheral: peripheral, error: Unknown error.)
- Disconnected

Logging on the Board the function "on_adv_evt" gets called with ble_adv_evt = BLE_ADV_EVT_FAST just like after a manual disconnection. There are no other errors logged on the board-side.

Is this Error related to the iOS-App?

[Mttrinh]

Hi,

Not sure if it related to the iOS app. Could you try with a different iPhone and see if it makes any difference?

Can you also try to test with an unmodified example from our SDK? Like the UART example.

the devices disconnect after about one and a half minute.

Is it always one and a half minute? Do you send anything or just leave it connected?

[hannes]

Hi,
thanks for the hints. It happend also to other iPhones and it was always after 95 seconds. Finally I found the Problem. It was the connection interval I've set to 8 and 20. I made several tests and it works fine with iOS when I changed the values to 8 and 30.