You are here

ISOC streaming on FX3 with Intel USB3 eXtensible host | Cypress Semiconductor

ISOC streaming on FX3 with Intel USB3 eXtensible host

Summary: 2 Replies, Latest post by sada on 06 Apr 2014 09:36 PM PDT
Verified Answers: 0
Last post
Log in to post new comments.
villepe's picture
3 posts

Hi all,

I would to have your opinion on this capture taken with my Lecroy USB3 analyser.

I'm using the FX3 for ISOC data transfer on EP3 with an Intel USB3 eXtensible host.

My ISOC burst size is 2x 12kB = 24kB.


I don't really understand why the host sent an ACK packet (n°7612029) before receiving the asked number of packet (NumP=4 packets expected, ACK sent only after 2 packets). Host seems to wait less time than usual before sending a new ACK (0,2µs here instead of 2,45µs in normal cases).

This behavior is really strange, because it causes a crash of my USB3 device under Windows7. After this crash, I need to restart the PC to use my device again. (The device still work fine, if I connect it on another PC).

Do you have any idea on the source of this behavior ? Is it the FX3 or the Intel host which is wrong ?

Thanks for your help



rskv's picture
Cypress Employee
1134 posts

Hi Villepe,

The trace that you attached to your post looks normal. Actually, host can send ACKs in advance.

Problem should be related to something else. Did you check the behaviour of this device with other hosts.

Are you seeing the same problem (crash) with other host controllers as well?


sai krishna.


sada's picture
1 post
Log in to post new comments.