Using Android to Communicate with a BLE HID Device

[bscdb]

Hi,

I'm trying to develop an Android app. My HID device is not a keyboard, mouse nor a gamepad. But my BLE firmware is based on SDK 15.2 & HID keyboard example code. I installed nrfConnect on my Android phone. The connection keeps dropping from nrfConnect app & I'm not able to read/write reports. My Android code connects to the nrf kit & recognizes the HID service UUID but then how do I read & write reports. Also I could read the battery level from battery service. I have kept the firmware code simple & I'm sending 8 bytes input report & receiving 1 byte output report.

[bscdb]

I tried another phone & I could connect & bond. But I could read /write to reports!!

[Sigurd]

So it was a problem with one particular phone ?

If the connection kept dropping, it would be good idea to take a look at the log and the disconnect reason, swipe from left to right in the nRFConnect app to bring up the log. You should also inspect the log on the nRF52-side. 

[bscdb]

Do you have a guide to do this?

[bscdb]

Also can you please provide .apk file of nrfconnect?

[Sigurd]

apk can be found here: https://github.com/NordicSemiconductor/Android-nRF-Connect/releases

I don't know if rooting the phones helps or not. Android apps are not supposed to access the HID characteristics...

[bscdb]

What if I create an app to convert Android phone into BLE HID device & it would be the central & it would communicate with peripheral BLE HID device. Is that even possible?

[Sigurd]

You can create your own app, but the HID keyboard service itself would need to be activated/connected in Android system settings -> Bluetooth.

As mentioned in the post I linked to earlier, "If you need to add some additional features to your keyboard, you have to use a different, custom service, that only your app will be able to understand. You may have HID and other services on one device. System will use the HID service, your app others."