nRF Sniffer wireshark bad interval connection

[MPS]

Hi all,

I'm using nRF Sniffer (2.0.0-1.beta), i didn't have any problem for follow connection between master and slave but now, I have a problem with time displayed in wireshark. My interval connection max is 20ms (central).

I can find in connect_req link layer data Interval 16 (20ms) => OK

After Wireshark shows that :

REF Master Slave LE LL 26 Empty PDU

0.000360 Slave Master LE LL 26 Empty PDU

0.000616 Master Slave LE LL 26 Empty PDU

0.000946 Slave Master LE LL 26 Empty PDU

0.001291 Master Slave LE LL 26 Empty PDU

0.001633 Slave Master LE LL 26 Empty PDU

0.102369 Master Slave LE LL 26 Empty PDU

0.102698 Slave Master LE LL 26 Empty PDU

etc....

Can someone explain to me what's wrong ?

Thanks in advance

Best regards,

MPS

[Sigurd]

Hi,

Could you save the sniffer trace(.pcapng file) and upload it here ?

[MPS]

Hi,

You can find in attached file the sniffer trace. Thanks in advance.

Best regards

sniffer.pcapng

[Sigurd]

Hi,

I don't really see anything very wrong here.

You can see from the delta time in the log, that the master send a new packet every ~20 ms, and that the slaves respond after 150 µs. Looking at the event counter, you can see that the sniffer sometimes misses some packets, and in that case the delta times will increase.

[MPS]

Thanks for your answer. Do you know why sniffer misses some packets. It's strange because it's always the same cycle : 3 received, 2 lost ... There is no correlation between the column "Time" with the reality ? Sorry but I started with nRF and this sniffer.

[Sigurd]

Are you placing the sniffer between the devices you are sniffing, as shown at page 3 in the sniffer user guide?

Regarding your question on the "Time column", this is explained in this post, quote:

The delta time ("end to start") is the one that is reliable. The "start to start" is not correct one. The time stamp on the TIME column also not reliable since it's the time stamp on UART on PC.