Re: [usb] usb bandwith

[Rudolf Usselmann <rudi@asics.ws>]

On Tuesday 13 August 2002 08:55 am, MeiZX wrote:
> hi,all
>   please help me to verify the three usb transfer rate 480Mb/s,12Mb/s,and
> 1.5Mb/s defined by usb specification.in full speed mode,one endpoint in
> isochronous mode can transfer 1023 bytes/ms---8Kbits/ms,8Mbits/s.that's
> to say,12Mb/s bandwith cannot be used up in full speed mode.is there any
> application that use alll the 12M bandwith? in high speed mode,considered
> the isochronous transfer,one frame includes 8 microframe.given three
> transactions can be transfered in each microframe,usb can deal with
> 24Mbytes/s,while half of its bandwith are useless.i cannot understand.

Yes, your numbers appear correct (I don't remember the details
but I think high speed can be faster). Things you should consider:

1) Devices may have more than one endpoint
2) There may be many many devices (printer, scanner,
    camera, speakers, CDROM, Hard Drive etc.)

Regards,
rudi

> regards
> 　　　　　　　　　　　　　　MeiZX
> 　　　　　　　　　　　　　　meizx@ict.ac.cn
> 　　　　　　　　　　　　　　　　　2002-08-13



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