Communicating between iOS and Android with Bluetooth LE
I've got a working app using CoreBluetooth to communicate between an iPad (central) and iPhone (peripheral). I have one service that has two characteristics. I have a Nexus 7 running the latest Android 4.3 with BTLE support. Android is a bit late to jump on the BTLE bandwagon but it appears they are approaching it similarly to how iOS did, where initially they only support acting as a central with the peripheral mode coming in a later version. I can load the sample Android BTLE app and browse for nearby peripherals. With my iPhone advertising as a peripheral I can see the value from CBAdvertisementDataLocalNameKey in the list of nearby peripherals on the Android side. I can connect to the iPhone and the Bluetooth symbol turns from light gray to black when the connection is made. The connection always lasts exactly 10 seconds and then disconnects. On the Android side I'm supposed to see a list of available services and characteristics appear immediately upon connection. I've proved the Android code is setup correctly because I can connnect it to the TI CC2541DK-SENSOR hardware that I have and all services and characteristics are listed upon connecting to it.
I've spent the last few days troubleshooting the issue with no success. The problem is I can't determine which device is experiencing an error and thus causing the disconnection. There are no callbacks from CBPeripheralManagerDelegate during the connection phase or service discovery phase so I have no idea at what point an error occurs (if the error is on the iOS side). On the Android side a method is called to initiate service discovery however their callback "onServicesDiscovered" is never called which is perplexing. Is there any way I can dig into the guts of the BTLE communication on the iOS side to see what's going on and determine what error is taking place?
Answer
I've already gone through this for at least one week having this same issue. I've already asked a question here and I've already answered on my own. The main problem is an Android BUG issue. It's sending a non permitted command on a fixed L2CAP channnel.
But when Android is communicating with normal peripheral BLE devices, it works pretty well. In fact, the BLE sample works like a charm. The problem is when is comunicating with an iOS device for example: Just after the connection is made, they start negotiating their connection parameters (this phase doesn't happen with normal BLE peripheral), and this is when the problem comes up. Android sends a bad command to iOS, iOS drops the connection. That's basically how it works
Some issues have been already reported to Google, and one of them have been already accepted and I hope they will start working on it soon.
Unfortunately, what you can do, is to wait until next Android release. Anyway, I highly suggest you to have a look at my issue report with all my test documents if you want to make some light on this problem.
Here's the link: https://code.google.com/p/android/issues/detail?id=58725