HID reconnection problem

[David]

I'm trying to save power on my HID keyboard application by disconnecting the Bluetooth link after some time of inactivity. As soon as there are keystrokes to send, the device advertises again and sends the pending values.

Generally I have 8 chars to transmit at once, but in Android 7.1.1 (Nexus 5X) I often get only 7 or less. The first one or two characters seem to get lost, although there is no error event generated by my nRF8001. I even get the right number of data credit events, so I assume the values have been sent correctly. The second value (again 8 chars) is always transmitted entirely.

I always wait for the first pipe status event after reconnection, sending data right after the connected event makes it even worse.

How can I achieve a reliable transmission of my first value? Is there some event to tell me that the master device is fully ready to receive keystrokes? Has someone experienced a similar behaviour and found a workaround?

[David]

Finally I managed to get a trace with the sniffer. Had to downgrade the Segger firmware on the PCA10000 dongle as described here: Sniffer not working PCA10000

As you can see, the connection is initiated at frame no 1965. The first notification is sent in frame 1969, but the master is still requesting some information. In this case the first 11 notification packets were not handled (characters not displayed) by the master. Is it allowed to ignore these first notifications? What should I do to be sure all my keystrokes are handled correctly?