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I have already paired peripheral ble device (iPhone) with my Android phone. Now I want from my Android code connect to this iPhone.

I received list of paired devices by mBluetoothAdapter.getBondedDevices() and try to connect to the proper one but connection fails (GATT_ERROR).

I know the mac address is randomizing but on the other hand this iPhone is paired and I am authorized to connect it. Can I do this?

Solvek
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1 Answers1

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In Bluetooth Low Energy, Pairing and Bonding are two different things as follows:-

  • Pairing is the process of encrypting the connection and exchanging security information.
  • Bonding is the process of saving the exchanged security information so that the device is properly detected (if it has a random address) and can immediately be paired to without further exchange of information.

In your case, if the devices are "paired" then this means that they are already in an active connection (This is different to classic Bluetooth where a connection and pairing are mutually exclusive). If this is the case, then try to list active connections to make sure that the iPhone is not one of them.

If you are "bonded" and not paired, then this means that there is no active connection and another one needs to be created. You will need to make sure that your peripheral device is advertising and that the Android device can scan and detect it. Once it is detected through the scan, connect to the iPhone and this should work without an issue.

This might be a useful reference:-

Should one create a bond with a Bluetooth LE device

I hope this helps.

Youssif Saeed
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  • So, if there is no active connection and iPhone is not advertising there is no way to connect to iPhone? How Amazfit watch connects to iPhone then? – Solvek Jan 31 '20 at 15:39
  • This is a standard BLE thing, in order to be connected to, you have to be advertising first. See this for more information: https://stackoverflow.com/questions/57969346/android-cannot-find-a-device-in-onscanresult-callback-after-successful-connect/57969750#57969750 – Youssif Saeed Jan 31 '20 at 17:59
  • But you can make it the other way around too. Let Android advertise and have an iPhone app that scans and connects to the Android. – Emil Jan 31 '20 at 23:57
  • With custom app on ios i have this problem solved. But unfortunally when this app is going to background android cannot connect to ios anymore. This is my problem. – Solvek Feb 01 '20 at 18:11