Re: 586 Evaluation Kit and USB slave driver using WinCE -- Support Forum for CompuLab's X86CORE & X86BASE Products

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Subject: Re: 586 Evaluation Kit and USB slave driver using WinCE

Author:
Gideon (for Vova)

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Date Posted: 04:28:47 08/05/02 Mon
In reply to: Chris Rupp 's message, "586 Evaluation Kit and USB slave driver using WinCE" on 14:23:01 07/18/02 Thu

Baud rate in USB Serial does not matter. It is implemented just to conform
to a standard of serial port, but changing it does not affect anything.

The slow speed of communication is not due to baud rate. I thing that it is
because of protocol you have implemented. For example if you send a data by
packets of one byte and then wait for acknowledge on each byte, you will get
a very bad performance. The better idea is to send a large blocks of data.

These restrictions are because USB is not really a serial port. It is only
an emulation and it has some drawbacks.

I will not write all the details of the protocol here, you can read about
them in the document on USB Serial (.DOC). However the basic line of
designing good protocol is sending big blocks of data with minimum
dependencies on acknowledges.

I tested the speed of USB Serial: it is about 100-130 KByte/sec. You may
even see it by running Zoom program that downloads target screen. If you run
ActiveSync on USB and disconnect network, you will see the speed of
downloading the image.

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Replies:

Subject	Author	Date
Re: 586 Evaluation Kit and USB slave driver using WinCE	rizky	21:48:29 02/23/03 Sun
Re: 586 Evaluation Kit and USB slave driver using WinCE -- John Drohan, 04:51:13 08/01/03 Fri