HID keyboard drains iPhone battery quickly

[Jeff]

I am connecting my development device acting as a BLE keyboard using HID over GATT and it seems to be draining the phone battery very quickly. Every 7 seconds I would get a pair of HID Suspend/Exit Suspend commands from the phone even when the phone screen is off and the keyboard is not sending any data. If I just connect using ANCS with my device I don't see the same power drain on the phone even when using the same BLE connection parameters. I saw this problem in iOS7 and it still continues in iOS8. Does anyone else see this issue? I cannot find any BLE keyboard products on the market to compare to.

ios8-hid.csv The attachment has the HID activity when the phone is idle. Handle 15 is the HID control point: developer.bluetooth.org/.../CharacteristicViewer.aspx

This is the frame data for the HID suspend/exit suspend commands. Frame 8,400: Len=27 ATT: Signature Present: No PDU Type is Command: Yes Opcode: Write Command Attribute Handle: 15 Unknown Attribute Data: 0x00

Frame 8,485: Len=27 ATT: Signature Present: No PDU Type is Command: Yes Opcode: Write Command Attribute Handle: 15 Unknown Attribute Data: 0x01

[Jeff]

I attached the capture of the HID activity in the original post. I cannot post the .cfa file because it contains confidential data that I cannot remove.

[Asbjørn]

Nordic has got a free sniffer to check the timing and content sent across the BLE link itself. It really helps us to know what timing parameters that's actually used, what kind of packages that' being sent and so on. If you have confidential content that you are concerned about for doing a sniffer trace and sending it to us I would ask you to open a case in the closed Nordic support system. There your information will be kept confidential.

[Jeff]

Thanks. I submitted a bug report to Apple a while ago and they replied asking for logs so they may be working on a fix on the phone side already. I will see if they fixed it in the next iOS release.