HID reconnection problem

RE: HID reconnection problem

run_ar — Fri, 25 Aug 2017 07:48:19 GMT

This looks like a limitation with the Android device. It should accept notifications as soon as you have encrypted the link again. Have you teste this with other masters? e.g. do you see the same behavior if you test with iOS?

RE: HID reconnection problem

David — Fri, 16 Jun 2017 14:32:04 GMT

Yes, the LL_START_ENC_RSP (line in blue) is sent before my first indication. My first indication is sent about 0.57s later, the last indication (black lines) even more than 1.2s after the encryption message but they are still ignored by the master device.

In this case the nRF8001 generates three identical pipe status events. Any notification sent before the third one seems to be ignored by the master device. Unfortunately sometimes there is only one pipe status event...

OK, waiting for about five seconds after the first pipe status event works fine, but this is definitely too long! Any idea how to make sure all the indications are received correctly?

RE: HID reconnection problem

run_ar — Fri, 09 Jun 2017 14:21:18 GMT

Did you check with a sniffer that the LL_START_ENC_RSP was sent before the notifications? Maybe you could try adding a small delay before you start sending notifications . or for testing use a long one, and see if that helps.

RE: HID reconnection problem

David — Tue, 23 May 2017 10:46:54 GMT

OK, thank you for the information.

But how can I know that the encryption process has been successfully completed? The nRF8001 does not generate any events...

Edit: In another thread (devzone.nordicsemi.com/.../), I found that the nRF8001 generates a pipe status event after finishing encryption. Waiting for this event works for some devices, but not all. Specially iOS devices seem to ignore the first couple of notifications. What do I need to do to assure a reliable data transmission after HID reconnection?

RE: HID reconnection problem

run_ar — Thu, 06 Apr 2017 09:22:39 GMT

You need to encrypt to re-establish the bond before you can start sending notifications. The Master doesn't recognise the peer until the LTK is verified, i.e. it doesn't know that this is a bonded peer and that notifications are enabled.

RE: HID reconnection problem

David — Fri, 31 Mar 2017 14:40:36 GMT

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?

RE: HID reconnection problem

run_ar — Fri, 31 Mar 2017 14:35:55 GMT

You should use version 1.10.x of wireshark for the sniffer. I'm sorry it's not more up to date.

RE: HID reconnection problem

David — Thu, 30 Mar 2017 13:16:31 GMT

Yes, I use a bonded connection. The first pipe status event shows that all previously opened pipes are still available. When sending keystrokes directly after the connected event, there are even more devices that do not display all of them. An iPad mini with iOS8.1 misses my first 2 or 3 characters, the Nexus 5X even up to 5 chars...

For information: All the tests are done with the Nordic ble_HID_keyboard_template.

I have an nRF51822 dongle (PCA10000) that should work as a sniffer, but I can't get it to work. Is there an updated version that would work with the actual version of wireshark (2.2.5)?

RE: HID reconnection problem

run_ar — Mon, 27 Mar 2017 11:11:00 GMT

Are you bonding to the peer? In this case you should be able to send notifications immediately after reconnecting.

If you are not bonded, you have to wait until the cccd's are enabled by the peer. However, you should get a PipeErrorEvent response from the nRF8001 if you try to send notifications when they are disabled. And I assume you see that the credits are used. Might be some issue with Android, so you have to wait for some time before sending the notifications. Do you have a sniffer trace that shows what is happening on air?