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USBTracer Recording Configuration


When looking at a Trace file taken with my USBTracer Classis, and I'm getting a whole bunch of SE0s? What is that?


There can be a couple of reasons for this depending on your recording configuration.

The most common reason is that the recording you made was on a branch below a hub. And the SE0 follows a packet where the host talks to a device, which is not attached to the branch you are recording. This can also happen if you have a USB mouse in one USB port and the device under test in the second port of a shared root (=same as a hub in practice). In these cases the SE0 is seen because the slave response is not relayed down the branch you are recording.

The second most common reason is the total lead length from host to device under test exceeds the 4.5-5m USB limit. You must remember that the CATC analyzer is a sniffer/hi impedance probe and does not repeat the signal the lead lengths of both cables connected to the front of the analyzer added together must be less than 5 meters.



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