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 created a test program that reproduces this problem: failure to receive events after a write or read request.  I have posted test program ImprivataTestNordicEventsNotReceived.zip and the main source file NordicTest-pc-ble-driver.cpp.   My intention is that you use the test program binaries, as described in the README.txt n the zip file. I included the source just so you can see what I'm doing, but I didn't include all headers to make it buildable.

[Jørgen Holmefjord]

Thanks for providing the example and detailed instructions. I have managed to run the test, and I have observed a few errors:

2020-02-05 17:18:11.814: sd_ble_gattc_read failed during characteristic_metadata_discovery_start error 0x0008 NRF_ERROR_INVALID_STATE, conn_handle = 0
2020-02-05 17:20:07.410: current GATTC read/write timed out
2020-02-05 17:20:07.410: sd_ble_gattc_read to keep connection alive got BLE_GATTC_EVT_TIMEOUT (which is allowable), so we must disconnect
2020-02-05 17:20:07.439: ERROR: sd_ble_gap_disconnect failed handle 0 error 0x3002 BLE_ERROR_INVALID_CONN_HANDLE
2020-02-05 17:20:43.446: current GATTC read/write timed out
2020-02-05 17:20:43.446: sd_ble_gattc_read to keep connection alive got BLE_GATTC_EVT_TIMEOUT (which is allowable), so we must disconnect
2020-02-05 17:20:43.507: ERROR: sd_ble_gap_disconnect failed handle 0 error 0x3002 BLE_ERROR_INVALID_CONN_HANDLE
2020-02-05 17:22:03.067: current GATTC read/write timed out
2020-02-05 17:22:03.067: sd_ble_gattc_write for characteristic notification got BLE_GATTC_EVT_TIMEOUT (which is allowable), so we must disconnect
2020-02-05 17:22:06.154: sd_ble_gattc_read failed during characteristic_metadata_discovery_start error 0x0008 NRF_ERROR_INVALID_STATE, conn_handle = 0
2020-02-05 17:22:39.167: current GATTC read/write timed out
2020-02-05 17:22:39.167: sd_ble_gattc_read to keep connection alive got BLE_GATTC_EVT_TIMEOUT (which is allowable), so we must disconnect
2020-02-05 17:22:39.254: ERROR: sd_ble_gap_disconnect failed handle 0 error 0x3002 BLE_ERROR_INVALID_CONN_HANDLE

I'm not sure if any of these are related to the issues you are seeing? How long does it normally take before the issue occurs with a single connection?

[Jørgen Holmefjord]

Sorry, I thought I had seen the log from you before but I missed it when I read through the post this time. This is strange, I'm not able to get into the state you describe. I have run two kits over the weekend, but I still receive events. I'm now testing with 3 additional dongles, no issues so far today. I will keep running the applications to try and reproduce the issue.

[Paul Bradford]

You wrote on Feb. 19 "I get the error and your program exits". Is somebody debugging to find/fix this? The test program exits when I do a read/write and get no events in response. That's the bug I need fixed. Everything that occurs after that failure to produce an event is secondary.

[Jørgen Holmefjord]

I also said that I always see a BLE_GAP_EVT_DISCONNECTED event in the log after the last GATTC_READ/WRITE, but before the expected GATTC_TIMEOUT. As I understood your next comment, you do not get any DISCONNECTED events, and the connectivity FW stops sending packets entirely? To me, this indicated that you are seeing a different behavior and that I have not managed to reproduce the same issue.

[Paul Bradford]

I do not receive a DISCONNECTED event.   I'll clean up and attach a revised test program that waits for either the GATTC timeout or the DISCONNECT event.

[Paul Bradford]

In a moment I'll upload new test program in 2020-02-24-TestProgramUploadedToNordicSupport.zip. When trying to connect, if it doesn't get the CONNECTED event or BLE_GAP_TIMEOUT_SRC_CONN, it will exit. When trying to read or write, if it doesn't get the read/write event, or the GATTC timeout or a DISCONNECT, it will try to disconnect, then exit.

[Jørgen Holmefjord]

I do not see this new application being uploaded yet. Did you complete it?

[Paul Bradford]

I must have made a mistake in the upload yesterday. I just tried again with a new zip file that has an updated README with the current text when the problem reproduces.

[Jørgen Holmefjord]

Ok, I'm testing with the new version of the application now. However, I have seen the "ERROR: never got BLE_GAP_EVT_CONNECTED or BLE_GAP_TIMEOUT_SRC_CONN after waiting 65000 milliseconds." message quite often in the log, but I did not manage to investigate or detect this in the logs, as the program did not exit from this error in the old version.

I'm a bit afraid that exiting on this issue will make it impossible to reproduce the GATTC_READ/WRITE behavior. Can you create a third version of the application that only exits on the GATTC_READ/WRITE issue if a DISCONNECTED event is not received in the 65 second timeout period?

Also, the Imprivata ID app keeps crashing/restarting all the time on the phone I have used for testing, could this cause some issues? I can try to get hold of another phone tomorrow if you think this could be an issue.

[Paul Bradford]

I just uploaded a new version of the test program in Feb25TestProgramUploadedToNordicSupport.zip.

This will only exit when GATTC_READ/WRITE don't get   BLE_GATTC_EVT_READ_RSP/BLE_GATTC_EVT_WRITE_RSP or BLE_GATTC_EVT_TIMEOUT or BLE_GAP_EVT_DISCONNECTED.

Leo from Fanstel had a problem with Imprivata ID crashing because his phone "does not have proximity sensor".   We do most testing with Samsung Galaxy and Google Pixel phones.

The problem "ERROR: never got BLE_GAP_EVT_CONNECTED or BLE_GAP_TIMEOUT_SRC_CONN after waiting 65000 milliseconds." is also a serious problem.  Why would a successful call to sd_ble_gap_connect not get one of those two events?

(I just remembered that I forgot to update the source file in the zip I just uploaded. If that matters, let me know)

[Jørgen Holmefjord]

Thank you, I have started the test now with 5 devices. The phone I see app crashes on is a Samsung Galaxy S7.

I agree that not receiving events after calling connect is also a problem. Now that I have both applications I should be able to debug both issues more easily.