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Re: USB Enumeration problem

Discussion in 'Embedded' started by bigbrownbeastie, Feb 24, 2010.

  1. On Feb 23, 11:54 pm, Joe Chisolm <> wrote:
    > mikecw_1968 wrote:
    > > I have a USB device (development board with firmware) that I connect to
    > > using Hyperterminal (or Tera Term).  When I power the device, connectit to
    > > the PC and bring up Hyperterminal, all is good.  It enumerates and I can
    > > connect.

    >
    > > At this point, if I cycle power on the device, after it comes up
    > > Hyperterminal will not communicate.  I then kill Hyperterminal and bring it
    > > back up but the COM port that was enumerated earlier is no longer in the
    > > list of valid ports.  

    >
    > > At this point, I disconnect Hyperterminal, cycle power on the device then
    > > reconnect.  All is well.

    >
    > > What am I not understanding about the USB initialization/enumeration
    > > sequence?

    >
    > > Btw, the PC is running Windows XP.

    >
    > > Thanks.

    >
    > > ---------------------------------------            
    > > Posted throughhttp://www.EmbeddedRelated.com

    >
    > Is your device using a CDC-ACM stack?  If so, I had the same problem.
    > It is not a enumeration problem but a Windows problem.  If you hook the
    > device to a Linux box with CDC-ACM support and use minicom, every thing
    > will probably work fine.  It has something to do with the way
    > windows deals with USB serial.
    >
    > --
    > Joe Chisolm
    > Marble Falls, Tx.


    There are some fixes around for this and involves WinXP SP3
     
    bigbrownbeastie, Feb 24, 2010
    #1
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