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]

So far I have not reproduced the problem in my test program, but I'm learning more:
1. Before the problem occurs, I receive expected events for the connection including BLE_GAP_EVT_RSSI_CHANGED and BLE_GAP_EVT_ADV_REPORT.
2. The failure to receive events always occurs after I have received notifications for a characteristic. I enable notifications for a characteristic (by calling sd_ble_gattc_write), then receive 14 BLE_GATTC_EVT_HVX events, which is the number I'm expecting.
3. Interspersed with those 14 events, I also receive other expected events, including BLE_GAP_EVT_RSSI_CHANGED.
4. After the 14th event, I never receive another event for that connection, as shown by USB capture.
5. I added a delay after getting the 14th event before doing another operation, so I can be sure the events stopped immediately after the 14 event. They did - no events were received (shown by USB capture) during that delay, or after.
6. After that delay, I can sd_ble_gattc_read or sd_ble_gattc_write call and USB capture shows the command and (successful) response, but no other traffic, specifically no events, for over 30 seconds, or afterwards
7. To summarize: after I finish receiving BLE_GATTC_EVT_HVX events, the nRF52840 ceases sending any events for the connection.