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TUSB1210 after FS/HS detection

Mike Perkins
Intellectual 565 points
Other Parts Discussed in Thread: TUSB1210

We can successfully complete the FS/HS detection, where we then place the TUSB1210 into HS mode with terminations.

We can see the J-K chirp on the PCB sent from the Host which are then reduced in amplitude as soon as the FUNC_CTRL is written with x"40".

While we can see the SOF signals on the scope, the TUSB seems to entirely ignore these.  After receipt of the chirp sequence there is no toggling of NXT whilst DIR is occasionally high with Data being x"0c" and x"0d" being seen  Sometime these are close together within a clock or two at the interface of 60MHz.

The PCB traces are short with the TSB1210 within 10mm of the connector, and the longest trace between the FPGA and the TUSB1210 is 31mm.

Power supplies are measured to be very close to the nominal voltage in each instance.

Given the short traces my assumption is that the PHY is faulty. Can anyone else explain this behaviour otherwise?

  • 0
    Intellectual 565 points

    I had a short stub of trace to an ESD device, which although only 3mm long it seems sufficient to stop the TUSB1210 from receiving HS data. (I note the layout guidelines suggest a max stub of 5mm)


    Now I am receiving SOFs. However amongst these SOFs I get a solitary "IN" packet which I did not expect. It does have a consistent address.

    Should I really expect an "IN" packet? before SETUP etc ?

  • 0 in reply to Mike Perkins
    Intellectual 345 points

    Hello Mike,

    If you have connected your device behind USB hub, you will get tokens intended for other devices on that hub as well as tokens intended for that hub. So you must ignore them and must respond only if device address in token matches with yours. Hope that helps.

    Have a Nice day.

    Regards,

    Bhaumik

  • 0 in reply to Bhaumik Darji
    Intellectual 565 points

    Brill, thanks very much for the info.

    Under these circumstances will I expect these tokens at a Fast Speed (ie with padding) if they were intended for a FS device?


    Thanks


    Mike

  • 0 in reply to Mike Perkins
    Intellectual 345 points

    Hi Mike,

    Sorry but would you please elaborate your question?

    Also here are some more questions:

    Are you connecting your device behind USB Hub? If yes, How many other devices are present on that hub?
    You mentioned you are getting SOF. Is your device working as a full speed device or high speed device?

    Regards,
    Bhaumik

  • 0 in reply to Bhaumik Darji
    Intellectual 565 points

    Hi Bhaumik,

    Yes my endpoint is downstream of a hub that has a couple of devices connected to it. I had no idea of the significance and thought a hub would be like a "switch" where only the relevant traffic would pass to the endpoint.

    My device initially appeared to be working at High Speed given the SOFs I receive and the spacing between the bytes. These would generally be contiguous at 60MHz with the occasional gap in a packet.

    After 100ms the host stops sending SOFs and so I attempt to place the device into suspend and Fast Speed etc. when the device wakes up, this is when I get the apparent Fast Speed "IN"s.

    I will have another look later today.

    Many thanks,

    Mike

  • 0 in reply to Mike Perkins
    Intellectual 345 points

    Hello Mike,

    After USB reset operation, host is expected to start enumeration process. It will ask for SET ADDRESS, GET DEVICE DESCRIPTOR etc. If you will not respond to these requests, after some time host will try to reset your device again. And in your case, it seems to me that during second attempt of reset, you are not sending chirp K to host, hence host decides attached device is full speed. And you start getting full speed tokens. 

    You are very likely to get tokens from host after USB reset. Are you responding to them? You should check that.

    Have a Nice Day!

    Kind Regards,

    Bhaumik