Minimum Requirements for Scanning Filters

RE: Minimum Requirements for Scanning Filters

Amanda Hsieh — Wed, 26 Aug 2020 07:25:58 GMT

Hi Ben,

These filters are intended to decide what device to connect to. You can see how they are used in nrf_ble_scan.c, in the nrf_ble_scan_on_adv_report() function.

The softdevice doesn't filter based on these filter settings. It is up to the application (nrf_ble_scan.c). Depending on whether all_filter_mode is true or false, you need to match all the set filters, or only one in order to trigger the NRF_BLE_SCAN_EVT_FILTER_MATCH event or not.

It will also call nrf_ble_scan_connect_with_target() which will connect to the target in case of NRF_BLE_SCAN_EVT_FILTER_MATCH if .connect_if_match is true.

So the assumption that the softdevice will filter out the advertisements and only pass the filter matched advertisements to BLE_GAP_EVT_ADV_REPORT event is not true. All advertisements will be forwarded to BLE_GAP_EVT_ADV_REPORT, but only the filter matches will be passed onto the NRF_BLE_SCAN_EVT_FILTER_MATCH event.

Is your code able to get inside the nrf_ble_scan_on_adv_report()? Does it match all the set filters?

-Amanda H.

RE: Minimum Requirements for Scanning Filters

RPDben — Tue, 25 Aug 2020 20:16:26 GMT

Both of these are set to 1

RE: Minimum Requirements for Scanning Filters

RPDben — Tue, 25 Aug 2020 20:14:59 GMT

Hi Amanda,

What do you mean by this? I have put a breakpoint on this part but it is never hit. Where should I be debugging the code? I am struggling as there are many devices discovered by the central so it is hard to pinpoint where I should put a breakpoint

Thanks,

RE: Minimum Requirements for Scanning Filters

hmolesworth — Tue, 25 Aug 2020 16:22:03 GMT

Worth a quick check: Did you set NRF_BLE_SCAN_UUID_CNT to 1, and NRF_BLE_SCAN_FILTER_ENABLE to 1?

RE: Minimum Requirements for Scanning Filters

Amanda Hsieh — Tue, 25 Aug 2020 12:33:05 GMT

Hi Ben,

The NRF_BLE_SCAN_EVT_FILTER_MATCH event is given in the nrf_ble_scan.c. You should debug the code to find out the reason why it didn't get.

-Amanda H.