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TUSB2046 cannot write to memory stick

Rein Anders Apeland
Prodigy 60 points
Other Parts Discussed in Thread: TUSB2046B, SN75240

Dear all,

I have a larger design with an integrated USB hub, implemented using the TUSB2046B chip.

It all works fine, on all four ports, with keyboards, mice, and a game controller.

However, when I connect a USB memory stick, I can only read from it, not write. When I try to copy files to it from Windows 7, it hangs several minutes on "Preparing to copy" before failing with something like "Cannot write to device". Reading works fine every time.

Putting the memory stick directly into my laptop USB port, all works fine.

Any ideas before I start delving into details, trying more than two brands of memory stick etc?

Hub schematics attached.

Best regards,

Rein A.

  • 0
    TI__Mastermind 18655 points

    Hello Rein,

    Could you attach the complete schematic?

    Download the usbview (7411.usbview.zip) utility to get more information about the hub and device. Select the item in the left window will allow its descriptors to be read in the right window. Could you attach some screen captures?

    Does the issue occur when the device is connected in all downstream ports?

    Regards,

    Joel

  • 0 in reply to Joel Jimenez0
    Prodigy 60 points

    Hello Joel,

    I am sorry I cannot attach the complete schematics without modifications. I wish I could. But the only thing not showing in the attached schematic, are the SN75240 USB filter chips. Could they cause this behaviour?

    However, I am using the USB extender LH1A from SEMICONN.DE, which I suspect _might_ cause the trouble I am seeing. I am using it to extend the USB link over 50m of Ethernet CAT6 cable.

    The funny thing is, however, that keyboard, mouse, and even a game controller works fine, together, over the USB extender in combination with the TI hub chip. Also, the memory sticks (I've tried two different brands) enumerates and mounts in Win7, and I can read from them. I can even write smaller files (100kb) to the sticks. But if I try to write e.g. a 2MB file, the system freezes.

    I was hoping someone with more intimate knowledge of the USB protocol details could shed some light on what _might_ be cause this behviour (only large file write fail, nothing else).

    I will do some more testing this week, both with and without the USB extender, and hopefully will narrow down the problems and know more by the weekend.

    Regards,

    Rein A.

  • 0 in reply to Rein Anders Apeland
    Prodigy 60 points

    Update:

    I have tested on a HP laptop running Win7 and a MacBook Air running OSX 10.9.1.

    The TUSB2046 hub chip is connected to the computer through an USB extender implemented using the USB-LH1A-CP chipset from SEMICONN.DE (and 50m CAT5e cable).

    I tried two different brands of memory stick, one noname and one Sandisk. None worked.

    However: If I try _only_ the hub chip or _only_ the extender, then all works fine. It seems that the interaction between the hub chip and the extender chipset is no good.

    Any ideas what could cause this? USB-package lengths? Simple HID devices work fine, but larger file transfers does not.

    Regards,

    Rein A.

  • 0 in reply to Rein Anders Apeland
    TI__Guru* 76130 points

    Hello,

    Please send more information about this extender, datasheet, schematic showing the connection from Host-Extender-Hub.

    When you say that the system works fine using only the hub, are you using also the 50m cable?

    Regards.

  • 0 in reply to Elias Villegas M.
    Prodigy 60 points

    Update:

    When using only the hub, I used an ordinary USB cable (1m). The 50m CAT5e cable is only to be used with the USB extender chipset. The extender chipset is _not_ only a passive amplifier/repeater. It is actively forwarding the USB protocol, AFAIK.

    However, after some testing and cross-testing, I found that there are no issues with my TUSB2046 HUB design. It works fine with any extender and direct connection.

    The issue was with the USB extender chipset (USB-LH1A-CP from semiconn.de). Either the chip is non-compliant or my design is flawed :-) The TUSB2046 works like a charm.

    Problem solved :-)

    -Rein

  • 0 in reply to Rein Anders Apeland
    Prodigy 60 points

    If of any interest: We're now using an off-the-shelf extender from Gefen instead (http://www.gefen.com/kvm/ext-usb2.0-lr.jsp?prod_id=5529).

    Thanks for all your help anyway :-)

    -Rein