Despite successfully reading scan request/response data (nRFconnect) Sniffer shows Advertising PDU type to be 0000 ADV_IND, not 0110 ADV_SCAN_IND

[Ron]

Hi

I have implemented a scannable advertising on nRF51822, s130, SDK12,

I can see it's working by reading the scannable information on nRC Connect, however,

on the sniffer I still see Advertising PDU type to be 0000 ADV_IND, not 0110 ADV_SCAN_IND as to my understanding it should be 0110.

If I did not actually advertise PDU 0110 why am I getting scan requests? I am happy that it's working but I don't understand why it is working.

Another related issue, is that even if I don't implement the scannable advertisement, I still get from time a scan request which is answered by a scan response (which seems to be empty),

So again, why am I getting scan requests without implementing it (obviously the PDU is ADC_IND 0x0000), and how is my advice answering those requests if it is not expecting them?

Thanks!

[Simonr]

Hi Eron

Please check out this blog post, where ADV_IND and ADV_SCAN_IND are explained in detail. Both of these can send scan response packets, but ADV_SCAN_IND indicates that it will accept scan requests but will not accept connection requests.

Best regards,

Simon

[Ron]

Hey Simon

Thank you for your reply,

1. If I understand correctly, there is nothing on the ADV_IND (0x0000) packet that flags the availability of scanning information?  the advertising packet will look the same?

2. If I didn't prepare data for scan response, SoftDevice just sends an empty scan response? Does that mean that it still needs to wait for a scan request with the receiver active (wasting power) and than transmit an empty scan response packet (wasting more power)? I practically save very little energy by NOT using scan response to convey data am I correct? the entire procedure will be available and active anyway? 

Thanks!

[Simonr]

Hi

1. The difference between ADV_IND and ADV_SCAN_IND packets is that the ADV_SCAN_IND packets won't accept connection requests, while the ADV_IND is able to accept both scan requests and connection requests.

2. Correct, there is no way to "forbid" the SoftDevice from sending a scan response when a request is received. You can check out this thread for a discussion with suggestions on how to disable scan response data, but if it's not specified in your project, the SoftDevice will send an empty scan response when receiving a scan request.

Best regards,

Simon

[Ron]

Thanks!