Disconnect for reason 8 after a couple of seconds if scanning while connected

RE: Disconnect for reason 8 after a couple of seconds if scanning while connected

Hung Bui — Mon, 30 Jul 2018 08:52:37 GMT

Hi,

You mean the connection was terminated because it was scanning ? I don't think it should be the case. Our scheduler should prioritize the connection if the connection is going to a timeout.

Could you change the clock to RC and test again ? Please send us a sniffer trace will multiple connection&disconnection so we can have enough data for our analysis.

RE: Disconnect for reason 8 after a couple of seconds if scanning while connected

Krastanov — Fri, 27 Jul 2018 18:48:26 GMT

Hello, Hung,

Thanks for the heads up about the SYNTH clock. I regrettably did not remember this while debugging, but I will keep it in mind in the future. The problem ended being annoyingly unrelated: the slave was not responding because the slave was also performing scans for packets from beacons.

It seem the softradio is incapable of sending acknowledgment Empty PDU packets while scanning (i.e. scanning for beacons while being connected to a master). I that right?

RE: Disconnect for reason 8 after a couple of seconds

Hung Bui — Fri, 27 Jul 2018 12:35:30 GMT

Hi Krastanov,

If you have a look at the S132 release note you will find this:

Synthesized low frequency clock source is not tested or intended for use with the BLE stack.

Please try to test again with the RC clock instead.

From the trace I can see a lot of missing packet and retransmission. Have you tuned your antenna ? Do you see the same problem if you test with our nRF52 DK ?

RE: Disconnect for reason 8 after a couple of seconds

Krastanov — Tue, 24 Jul 2018 05:25:17 GMT

The only reason nRF Connect does not disconnect is because it has **much** longer supervision timeout. When I lengthen the timeout of the other tools, they also perform the same way. So the question is, why does the peripheral just hang for a couple of seconds and then restarts working as if nothing happened!? What could cause the hangs?

RE: Disconnect for reason 8 after a couple of seconds

Krastanov — Tue, 24 Jul 2018 05:03:37 GMT

A particularly weird thing happens if I use the Nordic nRF Connect app, which might give a clue to what is happening:

The nRF Connect app connects successfully to the peripheral, just like the other apps or gatttools under linux or RaspberryPi. However, it does not disconnect after a couple of seconds unlike the other tools. Instead, if notifications are on, the notifications run (receiving a couple per second) until around the time when the other tools would have disconnected. At that point, instead of disconnecting, the nRF Connect just stops receiving notifications for a couple of seconds (without disconnecting). During that time I can see the peripheral reporting NRF_ERROR_RESOURCES (the peripheral retries when it gets that error and it has not been getting that error when using other connection tools on the master side). After a couple of seconds the peripheral stops reporting that error and the central (only under nRF Connect) continues getting new notifications as if nothing has happened.

By the way, all of this is done in an environment with very few on-air devices. There should be near zero interference from other BLE or WiFi devices.