Connecting to device using pc-ble-driver-py causes disconnect after 60 seconds

RE: Connecting to device using pc-ble-driver-py causes disconnect after 60 seconds

Ryan Lindeman (CAE) — Wed, 19 Feb 2020 18:01:26 GMT

I adjusted my Python central code to respond to the incoming "gap_evt_conn_param_update_request" event by attempting to call the ble_adapter.conn_param_update method but unfortunately it fails. I strongly suspect that the ble_adapter.py conn_param_update method is broken as there is no "status" key provided by the "gap_evt_conn_param_update" event.

As a workaround I am calling the ble_driver.ble_gap_conn_param_update method directly instead and holding off service discovery until I receive the initial gap_evt_conn_param_update_request. This seems to solve my disconnect problem for now.

devzone.nordicsemi.com/.../1538.controller.py

RE: Connecting to device using pc-ble-driver-py causes disconnect after 60 seconds

Ryan Lindeman (CAE) — Wed, 19 Feb 2020 16:57:23 GMT

I am already setting cp_init.disconnect_on_fail to false and it is still disconnecting.

RE: Connecting to device using pc-ble-driver-py causes disconnect after 60 seconds

Edvin — Wed, 19 Feb 2020 08:52:36 GMT

The fact that it comes during the discovery procedure shouldn't be a problem, but it is still something you need to handle.

Please look at some of the ble_central examples from our "normal" SDK.

E.g. in the ble_app_uart_c example, you can see the event in ble_evt_handler()

        case BLE_GAP_EVT_CONN_PARAM_UPDATE_REQUEST:
            // Accepting parameters requested by peer.
            err_code = sd_ble_gap_conn_param_update(p_gap_evt->conn_handle,
                                                    &p_gap_evt->params.conn_param_update_request.conn_params);
            APP_ERROR_CHECK(err_code);
            break;

Where it replies to the connection update request.

The answer to the request depends on the parameter preferences in the central projects sdk_config.h file.

NRF_BLE_SCAN_MIN_CONNECTION_INTERVAL and NRF_BLE_SCAN_MAX_CONNECTION_INTERVAL

This needs to fit the same parameters for your peripheral (they need to overlap).

An alternative, if you do not really care about the connection interval is to change something in your peripheral (if you have access to the source code for the peripheral).

Looking at the ble_app_uart (peripheral) example, in conn_params_init() in main.c, there is a parameter called cp_init which is used in ble_conn_params_init(&cp_init);

Make sure that cp_init.disconnet_on_fail = false; if you don't want the peripheral to disconnect if the connection parameters aren't satisfied (according to the min and max connection interval settings).

Best regards,

Edvin

RE: Connecting to device using pc-ble-driver-py causes disconnect after 60 seconds

Ryan Lindeman (CAE) — Tue, 18 Feb 2020 17:02:16 GMT

The Wireshark capture didn't catch the Connection Parameter request being made by the Peripheral. But upon further review on Friday I discovered the Peripheral is making the request but my Python Central code is not sending an appropriate reply. I'm attempting to rework my Central code to fix this and will post my final results. I believe this is the source of the disconnect. One challenge is that this tends to come in during service discovery which prevents the Central from receiving the reply from the Peripheral. Does Nordic plan to fix the EvtSync method to address these timing issues in the driver?

RE: Connecting to device using pc-ble-driver-py causes disconnect after 60 seconds

Edvin — Tue, 18 Feb 2020 14:53:29 GMT

Sorry for the late reply.

When you say ~63 seconds, could it be that it is 65 seconds? It sounds like that would be FIRST_CONN_PARAMS_UPDATE_DELAY + 2 x NEXT_CONN_PARAMS_UPDATE_DELAY. However, I can't see any parameter update requests in the sniffer trace. There should have been one approximately 5 seconds after the connection, and one after 30 seconds.

However, I see that it is the peripheral that decides to disconnect. Does the peripheral log say anything?

BR,
Edvin

RE: Connecting to device using pc-ble-driver-py causes disconnect after 60 seconds

Ryan Lindeman (CAE) — Fri, 14 Feb 2020 20:02:28 GMT

devzone.nordicsemi.com/.../controller.py devzone.nordicsemi.com/.../nrftester.py

Attached is the Python script which demonstrates the issue. Review the debug.log file produced.

python nrftester.py COM4

Using a nrf52832 development board as the central and probably peripheral. You will likely see what I see which is this line in the debug.log file:
2020-02-14 12:58:11.706 INFO controller - remote_close: Connection closed after 64.07205009460449 seconds with reason BLEHci.remote_user_terminated_connection

I believe that the Peripheral is initiating the close, but am unsure why. I have all of my sd_gap_disconnect code paths printing debug statements and I am not hitting any of them.

RE: Connecting to device using pc-ble-driver-py causes disconnect after 60 seconds

Ryan Lindeman (CAE) — Fri, 14 Feb 2020 00:00:33 GMT

devzone.nordicsemi.com/.../nrfConnect_2D00_no_2D00_disconnect.pcapng devzone.nordicsemi.com/.../pc_2D00_ble_2D00_driver_2D00_py_2D00_disconnect.pcapng

Attached are two wireshark captures showing the difference. I will analyze them myself tomorrow but hopefully something in the capture might be helpful.