Date: Mon, 10 Jul 2006 21:14:50 -0400 From: Gary Corcoran <gcorcoran@rcn.com> To: freebsd-usb@freebsd.org Subject: Re: Lowering USB Transfer Rate? Message-ID: <44B2FB8A.7010104@rcn.com> In-Reply-To: <20060710.084321.155333942.imp@bsdimp.com> References: <44ACC966.8030009@swehack.se> <200607101326.17709.frank@barda.agala.net> <20060710.084321.155333942.imp@bsdimp.com>
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M. Warner Losh wrote: > In message: <200607101326.17709.frank@barda.agala.net> > "Frank J. Beckmann" <frank@barda.agala.net> writes: > : there is no difference in cables between USB 1.1 and 2.0. Only special low > : speed cable for low speed devices may be different. > > Actually, there *IS* a difference between 1.1 and 2.0 cables. The > plugs on the ends are the same, however. The problem is that you can > get data dropouts using 1.1 cables to get 2.0 speeds. Ummm - I thought one of the design goals of USB 2.0, which Intel *knew* they were going to do while USB 1.x was coming out, was to be able to use _exactly_ the same cables. Which is why they specified such good, braided full shielding cables, were required for USB 1.x. And why they didn't change the connector - because the (unknowing) consumer then wouldn't have to worry about whether they had the "right" cable. If they really were intended to be different, wouldn't they have changed the connector? Of course as Frank alluded to, there may have been some unscrupulous manufacturers making el-cheapo cables, which they knew they could get away with for low speed USB 1.x devices. Is that what you were referring to, Warner? Or what (specifically) are you talking about? But as far as I know, general, well shielded USB cables, from reputable manufacturers, should be usable for USB 2.0, even if they were manufactured during the USB 1.x days. It's easiest to tell with the clear jacket cables showing you the full braided shielding... ;-) Gary
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