pc-ble-driver no scan response

[Torsten Robitzki]

I want to incoorperate the pc-ble-driver into a product, using the PCA10059 USB-dongle. My design requires me to receive advertising scan responses. I successfully receive advertising events and I see both, scan resquests and scan responses with a sniffer, but I never receive any scan responses. According to the debug messages, printed by the pc-ble-driver I suspect that scan responses are never send from the PCA10059 to the connected PC.

I expect the `type.scan_response` field in the received `ble_gap_evt_adv_report_t` event to be set once in a while.

Any idea, why I do not receive any scan responses? Do I have to configure the reception? A'm I'm using the wrong connectivity firmware?

I'm using the connectivity_4.1.1_usb_with_s140_6.1.1 with an PCA10059 1.0.0 on OS/X 10.14.5.

See attached, the sniff and the logfile.

best regards,

Torsten

no_scan_response.pcapngno_scan_response.log

[Torsten Robitzki]

Interessting my scan response also contains Manufactorer Specific data.

[Torsten Robitzki]

Hi Jørgen,

I hope you are doing well. Are you on vacation?

best regards,

Torsten

[Torsten Robitzki]

While further investigating this, I build the connectivity firmware (debug build) and deployed it onto a PCA10056 (to be able to debug it). With this setup, I receive scan responses once in a while. I made some measurements and found that in most times (5 out of 9), it takes 40 to 50 seconds to receive a first scan response from a specific address, while in all other times (4 out of 9) it takes 2 to 4.3 seconds to receive a first scan response.

The specific address I'm looking at, advertises with an interval of ~110ms (according to the sniffer). The time it takes to receive a first scan response devided by the number of received advertising PDUs (ADV_IND) is roughly 2 times 110ms for all measurements. I would expect ~110ms / 3, as the scanned device advertises on all three advertising channels. And of cause during all periods, there are plenty of scan requests made by the connectivity firmware and scan responses by the device.

In my setup, I had to configure the pc-ble-driver client with a baudrate of 100,000 (not 1,000,000 as in the examples). Could this be some kind of congestion on the USB part? If so, why are advertings priorizes over scan responses?

[Torsten Robitzki]

Now I added some LED toggles into the connectivity firmware. In `ble_gap_evt_adv_report_t_enc()` I toggled different LEDs. One LED is toggled for every call to the function, one LED for every event with the MAC address of my device. And finaly, one LED for every scan response. The toggle schema of the LED is comparable to what I receive on the PC side. So nearly no scan responses are reportet to `ble_gap_evt_adv_report_t_enc()`.

On the calling side of `ble_gap_evt_adv_report_t_enc()`, I made sure, that in `ser_conn_ble_event_encoder()` allocating memory is not causing a problem. `ser_hal_transport_tx_pkt_alloc()` never fails.

So I traveled up the call stack and found that in `ser_conn_ble_event_handle()` events are scheduled onto an application queue (`app_sched_event_put()`). So I moved my LED blinking test code infront of the scheduling. Same pattern here, so no events get lost, due to this scheduling.

Further up the call stack, there is just `nrf_sdh_ble_evts_poll()` which calls `sd_ble_evt_get()` and just calls `ser_conn_ble_event_handle()` indirectly. Moveing the LED blinking test code there, reveals the same results.

So it seems, the Softdevice is sending scan requests, the device is responding with scan responses, but the SD is not reporting the responses. Why is that?

[Torsten Robitzki]

An other observation is, that according to the attached sniff (no_scan_response.pcapng), my device is responding on the next advertising channel and the response time is way behind T_IFS. But I would expect this to be an Nordic Sniffer issue, as receiving scan responses, just by using the OS/X API works as expected.