USB Enumeration problem

I have a USB device (development board with firmware) that I connect to
using Hyperterminal (or Tera Term).  When I power the device, connect it 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.


	   
					
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Posted through http://www.EmbeddedRelated.com

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, connect it 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 through http://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.

On Feb 23, 11:54=A0pm, Joe Chisolm <jchiso...@earthlink.net> wrote:
> mikecw_1968 wrote:
> > I have a USB device (development board with firmware) that I connect to
> > using Hyperterminal (or Tera Term). =A0When I power the device, connect=
 it to
> > the PC and bring up Hyperterminal, all is good. =A0It enumerates and I =
can
> > connect.
>
> > At this point, if I cycle power on the device, after it comes up
> > Hyperterminal will not communicate. =A0I then kill Hyperterminal and br=
ing it
> > back up but the COM port that was enumerated earlier is no longer in th=
e
> > list of valid ports. =A0
>
> > At this point, I disconnect Hyperterminal, cycle power on the device th=
en
> > reconnect. =A0All is well.
>
> > What am I not understanding about the USB initialization/enumeration
> > sequence?
>
> > Btw, the PC is running Windows XP.
>
> > Thanks.
>
> > --------------------------------------- =A0 =A0 =A0 =A0 =A0 =A0
> > Posted throughhttp://www.EmbeddedRelated.com
>
> Is your device using a CDC-ACM stack? =A0If so, I had the same problem.
> It is not a enumeration problem but a Windows problem. =A0If you hook the
> device to a Linux box with CDC-ACM support and use minicom, every thing
> will probably work fine. =A0It 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