disconnecting while operations are in progress never gives BLE_GAP_EVT_DISCONNECTED event

[Paul Bradford]

2020-01-24-092119EST-ProductStoppedGettingEventsFromNordicDK.txtImprivataTestNordicEventsNotReceived.zipCalls_to_pc_ble_driver.cpp0285.2020-02-24-TestProgramUploadedToNordicSupport.zipFeb25TestProgramUploadedToNordicSupport.zipImprivata_bgTestApp.zipbgSDKTestAppMay4.zip2020-05-05-035347-NordicDK_USB840M_200505_ClockInternal_2in1.hex.txt.txtbgSDKTestAppMay6.zipI’m developing an application based on pc-ble-driver to talk to an nRF52840-based dongle (from Fanstel).

I’m having trouble disconnecting cleanly when a connection has operations in progress.  For example, I call ‘sd_ble_gattc_write’, which returns NRF_SUCCESS, but I don’t receive event BLE_GATTC_EVT_WRITE_RSP (after waiting 60 seconds), so I decide to disconnect. When this happens, sd_ble_gap_disconnect returns NRF_SUCCESS, but I do not receive BLE_GAP_EVT_DISCONNECTED even after waiting 30 seconds. The connection supervision timeout is 4 seconds.  What could cause the disconnect to not generate any BLE_GAP_EVT_DISCONNECTED event?

What I’m trying to accomplish here: if a connection is not responsive, I want to end that connection, without disturbing other connections I have open.

Thanks,

Paul Bradford

[Paul Bradford]

I have attached a new test program Imprivata_bgTestApp.zip. There is a file called README with instructions, and a description of the problem.   I suggest you try this on a Dell 64-bit Windows 10 laptop that has not had Nordic dev tools installed on it. Usually the problem occurs with in an hour or two.

This test program reproduces the problem on two 64-bit Windows 10 laptops and does not reproduce this on one 64-bit Windows 10 laptop. I don't know what difference between these laptops causes two to fail and one to succeed. All have the same driver usbser.sys 10.0.18362.1 winbuild 160101.0800. Problem has occurred when plugged into USB 2.0 and USB 3.0 ports.

Failing laptops: both Dell, one Windows 10 version 1903 build 18362.657, another Windows 10 version 1909 build 18363.752 (the latest public Windows 10 build)

Laptop that does not reproduce the problem: Lenovo ThinkPad, Windows 10 version 1903 build 18362.657 (exactly the same as one failing laptop). This one has had Nordic tools like nRF Connect installed. One consequence is that when I plugged in an nRF52840 it would show in Device Manager as 'nRF Connect USB CDC ACM (COMx)'. To make it like my other laptops that do not have Nordic tools, I uninstalled the driver so that the nRF52840 would show up as 'USB Serial Device (COMx)'

[Jørgen Holmefjord]

I have had the new application running on my PC with 5 parallel devices for 8 hours yesterday and 4 hours today. So far, I have not been able to reproduce the issue. I do have another PC that does not have Nordic tools installed, but this is not a Dell PC. I will try to setup the test on that one next. It's a bit harder to find equipment for testing this with the limited factors where you have managed to reproduce the issue, due most of us working from home-office due to the Corona situation. Is it still a requirement to have heavy Bluetooth activity around the device in order to reproduce the issue? This could also be a problem to facilitate during home-office.

[Jørgen Holmefjord]

Paul Bradford said:

after a prolonged period of receiving no advertisements

Does this include all advertisements or only advertisements from the tracked phone? How long time is "10 timer ticks"? I see this message a lot when I leave the phone for a while, it kinda seems like the phone/application enters some kind of state where it pauses/terminates the application. I have tried to disable power optimization for the app on the phone. I have verified with the 's' command that the phone is actually being tracked, but sometimes it does report that it is not tracked, until I unlock the phone. I have not purposedly set any configs on the phone side, it should use the default settings of the Samsung Galaxy S7. I do not see this event on when testing Huawei P30 Pro.

Let me know if you are not able to wire the pins for logging, I can build you a version with log on P0.06.

@leochen: I was not able to reproduce the original issue with RTT logging enabled/RTT Viewer open. If you are always running this with the firmware, it could be the reason that you did not manage to reproduce the problem.

[Paul Bradford]

"Receiving no advertisements" means any advertisement at all, not just from the tracked phone.  The timer tick is a one-second period where we aren't doing any work other than scanning - since we're only scanning, we expect we'd received advertisements.  Between timer ticks we do stuff like connecting to phones, so N timer ticks can be much longer than N seconds.  This issue of not receiving advertisements is a real problem that I'll need to resolve, but I don't want it to interfere with this support case, so I've uploaded modified test program bgSDKTestAppMay6.zip that doesn't reset the nRF52840.

I was able to wire the pins for logging. I removed the wire to use Leo's firmware that did RTT logging (which so far is not reproducing the issue).

[Jørgen Holmefjord]

I did a quick test run with logging enabled for all SD events and function-calls in the connectivity FW. I tried to synch the clocks as good as possible (second accuracy), as the logger and application run on different computers This is the output from your application:

2020-05-06 20:58:36.352: (WARNING) restart scanning because we've gone 10 timer ticks with no advertisements

This is the log file from the connectivity FW: 20200506_sdcalls_events.log

From what I can see, it looks like there are ADV_REPROT events generated about every 1-2 seconds before the reset in your application, so I'm not sure if the events are not passed fast enough to your application, or if they are not processed quickly enough in your application. There is also a huge amount of RSSI_CHANGED events, which may slow things down. Do you require to be notified on every RSSI change in your application? You can set the threshold/skip count in the softdevice API call: sd_ble_gap_rssi_start().

What connection parameters do you have for the connection? From the RSSI events, it could look like the connection interval is set to 30 ms? What about connection event length, slave latency, etc? This will all affect the available radio time for doing scanning. Since you are doing advertising simultaneously, you may reach the radio time limit if your parameters are not carefully selected. Check out the Scheduling chapter in the softdevice specifications.

[LeoChen]

Hi,

The following link for log on P0.06, clock internal.

https://www.dropbox.com/s/q7ddx4zqw86x0q4/USB840M_200527_UARTLog_Pin6.rar?dl=0

[Paul Bradford]

I’ve had Leo's firmware USB840M_200527_UARTLog_Pin6.rar, from late on May 6, running on two devices for three days without ever seeing the ‘no event’ error. I’m happy to say this seems to be solved. I’ve  had it running on the Fanstel dongle and the Nordic Development kit.

I'll summarize all the changes since this support case started.

1. In my application, sd_ble_gap_connect was being called with ble_gap_scan_params_t.timeout=0 so that if the connection was not established it would not receive event BLE_GAP_EVT_TIMEOUT(BLE_GAP_TIMEOUT_SRC_CONN)

2. In my application, all the sd_ble_gattc_* operations needed to watch for event BLE_GATTC_EVT_TIMEOUT to indicate the operation would not complete successfully

3. In my application, all the sd_ble_gattc_* operations needed to watch for event BLE_GAP_EVT_DISCONNECTED to indicate the operation would not complete successfully.

4. In the connectivity firmware, fixed race condition around resuming SoftDevice events, see April 24 post from Jorgen. SDK file examples\connectivity\ble_connectivity\main.c

5. In connectivity firmware, increase scheduler queue size from 16 to 64, see Jorgen post April 29, and in more detail on May 5: change SER_CONN_SCHED_QUEUE_SIZE from 16 to 64 in SDK components\serialization\connectivity\ser_conn_handlers.h

The only remaining step is to get those changes into the released SDK.

Thanks,

Paul