Unexpected packet in beacon scanner.

[cl]

Hi.

I'm currently receiving advertisement packet from beacon scanner app. (nrf51822) (ble_peripheral/experimental_ble_app_multiactivity_beacon/hrs_scanner)

I tried to receive advertise packet with only specified UUID.

To do that I checked UUID in p_evt handler function as follows.

beacon_evt_handler(ble_scan_beacon_evt_t * p_evt) {
   if(uuid_cmp(p_evt->rcv_adv_packet.adv_data.uuid.uuid128, specified_UUID, UUID_LENGTH) {
      ....
   }
}

I compared "p_evt->rcv_adv_packet.adv_data.uuid.uuid128" value with specified UUID. (for ex. 0x00112233445566778899aabbccddeeff)

And I set up another nrf51822 board as a beacon advertising with specified UUID.

So, there're 1 beacon scanner & 1 beacon configured for a certain UUID.

I guessed that beacon scanner would get advertisement packet of UUID(0x001122...) only from that beacon.

But, not like my expectation, other advertisement packets comes into beacon scanner.

I mean, other beacon(that are configured to have different UUID) advertisement packets.

That packets has unexpected value but with specified UUID.(0x001122...)

I don't understand how other beacon's advertisement packet has custom UUID.

I checked out address value of these strange packets.

and I found that owners of these packet are other devices. ( other beacon scanner, ble device - not iBeacon device, etc)

But, there's no clue how they have same UUID that I specified as custom. (0x001122...)

Is there some sort of broadcasting feature in ble or beacon? (If it is, then, how can I filter out that?)

And one more question for setting up beacon scanner.

Is it possible to setup beacon scanner without advertising?

When I stop advertising in beacon scanner it dies.

I just want to receive advertisement of other beacons. not advertising.

Thanks in advance.

[Anders Strand]

Hello.

When scanning, you will get advertising packets from all devices around you. It is up to you to filter the advertisement packets (Like you are doing in beacon_evt_handler). It does not make any sense that the other advertisement packets have the same uuid. Are you sure of this? Maybe there is a bug in uuid_cmp? For example if the uuid is NULL?

Is there some sort of broadcasting feature in ble or beacon?

Yes. Broadcasting and advertising is basically the same thing. Non-connectible advertising is often called broadcasting. This is how a BLE beacon broadcasts its packets. A BLE beacon is simply a device advertising a specific packet with the "non-connectible" flag set. You cannot filter it out, as it is what you are scanning for.

Is it possible to setup beacon scanner without advertising?

Yes. In main(), the line

err_code = ble_advertising_start(BLE_ADV_MODE_FAST);

starts the advertising.

[cl]

You're right. After inserting memset() code, strange packet is no longer detected in scanner! So it seems like it's just problem of scanner not clearing default value of evt struct. Thanks!