Processing malformed packet by SoftDevice

[Martin Muhady]

Hi,

I'm using Nordic BLE Sniffer. When I look into the captured data I see a lot of malformed packet (CRC error). It try to decode any received data even if there is CRC error. Probably for this reason I see a lot of non-existed source addresses (I've highlighted only one but there is a lot more):

 

Does SoftDevice process only valid packets? It means only packets with valid CRC? Can I see some counter about portion of malformed packets?

And what about if I receive packet with valid CRC but with malformed PDU?

Thank you a lot.

M. 

[Einar Thorsrud]

Hi,

I do not recommend trying to make sense of packets with CRC errors, as you know they are corrupt.

Regarding the SoftDevice, it will discard packets with CRC errors, so it is effectively a lost packet. No information about the packet or number of packet losses is reported to the application. (The only exception is when the number of consecutive packet losses causes a supervision timeout, which is reported to the application as the disconnect reason.)

[Martin Muhady]

Thank you a lot it makes sense. And what is the behavior of softdevice when CRC is correct but structure of PDU do not match with BLE standard? for example if in Advertising Data -> Manufacturer Specific Data length is 250.