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Updated version of ezusb.sys ? My version is 1.1 from 2001 / 2002 from cypress website

Discussion in 'Embedded' started by Martin Maurer, Nov 6, 2004.

  1. Hello,

    can someone tell me if there is a newer / improved version of ezusb.sys then
    version 1.1 which can be downloaded from cypress website ? I saw the latest
    change was in september 2001.

    I googled around and read, that on http://www.devicedriver.com/ they write,
    you shouldn't use it for production because of bugs. Is this still valid
    today or were the mentioned bugs removed from current cypress code ? Is it
    worth buying a license ? What kind of bugs are inside the code ?

    Another question on IOCTL_EZUSB_BULK_READ: I often see that as size for the
    DataBuffer 0x8000 is used. Increasing it further to 64 KB seems not to work.
    Why this limitation ? Is overlapped reading supported ? Any other ideas how
    i can further increase bandwidth (currently 17 MB/s, with external IFCLK of
    24,576 MHz) ?


    Martin Maurer, Nov 6, 2004
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  2. Martin Maurer

    Dan Guest

    You can get a free copy of the latest ezusb.sys driver (V1.30.0.0)
    from the Cypress web site.
    You will have to install the entire development kit in the default
    directory, the source code and driver will be located in

    I don't know of any "Bugs" in the ezusb driver. The driver has very
    limited functionality. I think the only reason Cypress says that this
    is "not for production" is that they do not want to take any
    responsibility for this driver in someone else's product. One of the
    limitations of this driver is that the IOCTL_EZUSB_BULK_READ in
    version 1.30 is limited to 64K. Another limitation of this driver is
    that it does not support overlapped reading. Cypress has always said
    they have no plans to improve this driver, except to support new ezusb
    chips, that "you should write your own driver" and that the exusb
    driver is only for development purposes.

    A Cypress app note for the exusb FX2 chip (usb 2.0) "Streaming Data
    through Isochronous/ Bulk Enpoints on EZ-USB FX2"
    states that the throughput will max out at 24MBps. To get this
    high-bandwidth transfers it uses the CYdvk.sys driver that supports
    three 1024 byte packets per microframe.
    Dan, Nov 20, 2004
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