nRF8001: using pipes immediately after re-connecting

[Stephan Walter]

Hi, I'm using an nRF8001 with a locally stored GATT service and security enabled.

I have already established a bond with a master device. The master has enabled notifications/indications for the appropriate characteristics of the GATT service and disconnected.

When I reconnect, I wait until the first bit in the PipesOpen bitmap indicates that pipe discovery has finished and the relevant pipes are open. I then try to send data on a pipe (by Indication or Notification). This data never seems to arrive at the master.

If I wait about 5 seconds after connection has been established, and then send the data, it works fine.

This happens both with the USB dongle from the evaluation board (nRF2739) and with a custom app on an Android smartphone (Galaxy S4).

Am I doing something wrong? As a workaround, I can simply use a delay of about 5s, but I would like to know the reason behind this behavior.

I tried disabling encryption to record a packet trace using a sniffer, but without encryption, the problem does not occur.

Any help would be appreciated. Best regards, --Stephan Walter

[David Edwin]

1. Can you upgrade to the latest version of the master control panel that you use with the nRF2739 and test the behaviour again ?
2. Can you increase the nRF8001 configuration -> Security ->Security Request Delay to 10 seconds and the Bond time out to 600 seconds and re-test.
3. If the above 2 suggestions did not fix the issue. Can you give me a log of the Events that are coming from the nRF8001 on the re-connection. Ideally when a Pipe is open it is available for use.

[David Edwin]

The root cause of the problem is likely that encryption of the link did not finish before data was sent on the Pipe, so if your script gets connected to a device for which you have the encryption keys, you must encrypt the link as the first thing to do on the link. Please accept my answer if this has helped you.