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TUSB212: Problem with eye diagram test

Alessio Cocchi
Prodigy 110 points
Part Number: TUSB212

Hi all,

i'm using TUSB212 in a design, and i'm trying to perform the Eye Diagram test with the oscilloscope.

The problem is that i see no differences between the test performed with TUSB212 in reset, and TUSB212 out of reset. When i de-assert the reset, the  DC_BOOST/ENA_HS pin is at 0.5V, so i think it's not anymore in High Speed mode (and it isn't boosting line voltage).

It's look like TUSB212 exit the High speed mode when the USB port is in test mode.

I'm Using a Tektronix DPO 7254C with it's own USB Test Compliance Package, the Boad processor is the IMX6 Quad. The USB port is put in test mode with the Allion HSEHET B017 test fixture.

any suggestion?

thanks to all

Alessio

  • 0
    TI__Expert 3655 points

    Please look at post below.

    the steps per USB IF and datasheet needs to be followed.

    e2e.ti.com/.../469595

  • 0 in reply to WIN Maung
    Prodigy 110 points
    I've already follow the procedure, but if i de assert the reset of TUSB212 before put the IMX into Test Mode, the Port tells me that can't enumerate the device (the HSEHET board), so the IMX cannot enter test mode. Looks like TUSB doesn't allow the High Speed negotiation.
  • 0 in reply to Alessio Cocchi
    TI__Expert 3655 points

    Looks like you are doing embedded host eye test so the standard host test procedure do not applies.

    It is closer to device test procedure but

    for

     embedded host make sure you cannot with test fixture switch in enumeration mode first.


    if started you started up with switch in the test load first the tusb212 will go into the eye compliance test mode and it will cause enumeration failure.

    so start with enumeration first and send test patttern and switch to oscilloscope load

  • 0 in reply to WIN Maung
    Prodigy 110 points 
    If I understood correctly, when i connect the Test Fixture to my chain, the TUSB212 is the first "device" that will go into test mode right?
    In the datasheet there isn't any reference to a Test mode of TUSB212.
    Assuming that the test mode is present, how can i test the IMX-->TUSB212-->USB_Receptacle chain? If i put first IMX in test mode, than i de-assert the reset for TUSB212, it will not recognize an high speed connection an doesn't work.
  • 0 in reply to Alessio Cocchi
    TI__Guru**** 177476 points

    Alessio

    1. Connect the USB Test Fixture to the embedded host

    2. Connect  Allion HSEHET B017 test fixture to the Test fixture 

    3. Use any specific steps or commands to enable the Host to send Test Packets (This step may be specific to each platform).

    4. Start sending Test Packets

    5. Switch Test Fixture from “INIT” to “TEST” to Capture Test Packet on scope to display eye (Running Compliance software on the scope)

    Does these steps work?

    Thanks

    David

  • 0 in reply to David (ASIC) Liu
    Prodigy 110 points

    Hi David,

    these steps doesn't work.

    I'm not sure that you have understand which fixture i'm using:

    The one one the left, is the fixture used to probe with the differential probe the signal from the USB Receptacle of my board, the one on the right, set on mode 4, put the host in Test Mode. The IMX6 itself can't enter test mode without this board (in my case). The two board are independent (you don't need to connect Hsehet to the other). So the steps of your procedure are not applied to the letter in my case.

    Thanks

  • 0 in reply to Alessio Cocchi
    TI__Guru**** 177476 points

    Alessio

    Are you saying that you first enumerate the embedded host+ TUS212 so the embedded host sending out the test packet, you then disconnect HSEHET and plugging in the high speed test fixture (host SQ)?

    Thanks

    David 

  • 0 in reply to David (ASIC) Liu
    Prodigy 110 points

    Yes, i'm doing exactly those steps.

  • 0 in reply to Alessio Cocchi
    TI__Guru**** 177476 points

    Alessio

    Thanks for your response. Once the Allion device is removed, TUSB212 could get out of HS Boost mode if the output voltage swing doubles and it detects a disconnect event, even though the embedded host might be sending the test patterns at that point. So much like in the case of device testing the termination needs to be switched in quickly (within 400ms) after the Allion device has been disconnected so that TUSB212 does not detect a disconnect and get out of test mode. 

    Thanks

    David