In article <
timstreater-76D0...@news.individual.net>,
> > isw wrote:
> > > In article<k13r6c$7v1$
1...@dont-email.me>,
> > > Phillip Jones<
pjon...@comcast.net> wrote:
> > >
> > >> Paul Sture wrote:
> > >>> On Wed, 22 Aug 2012 10:35:30 -0700, nospam wrote:
> > >>>
> > >>>> In article<isw-4B846D.10221122082012@[216.168.3.50]>, isw
> > >>>> <
i...@witzend.com> wrote:
> > >>>>
> > >>>>> All the "transfer cables" I've seen have a lump in the middle. I'm
> > >>>>> pretty sure it's just a two-port USB hub. Might require a special
> > >>>>> "password" of some sort just to lock you into their software. though.
> > >>
> > >> The lump in the middle of some USB cables is a filter. when USB first
> > >> came out the power and sign al wasn't so clean so filters were added to
> > >> the cables.
> > >
> > >
> > >
> > > Isaac
> > say what.
> >
> > There two Standard, USB cable (not talking about the items in this thread)
> >
> > USB-A to B
> > USB-B to B
> >
> > The US-A End general general Plugs into a Device.
> > The B end plugs into the computer.
> >
> > in last few years there have been three new types
> >
> > USB to Mini
> > USB to Micro these are used generall on Phones.
> >
> > The latest standard is USB3
> >
> > I am sure there are variations on the above A-B, B-B, B-Mini, and
> > B-micro in the USB3 standard.
>
> None of this is relevant. What *is* relevant is what Isaac said: Any
> cable where both ends can mate directly to computers is not a "legal"
> USB cable.
>
> The type of connector in use is not germane to the issue.
Sure it is--that's how the USB spec is written:
> 5.2.2 Compliant Cable Assemblies
> The USB 3.0 specification defines the following cable assemblies:
> � USB 3.0 Standard-A plug to USB 3.0 Standard-B plug
> � USB 3.0 Standard-A plug to USB 3.0 Micro-B plug
> � USB 3.0 Standard-A plug to USB 3.0 Standard-A plug
> � USB 3.0 Micro-A plug to USB 3.0 Micro-B plug
> � USB 3.0 Micro-A plug to USB 3.0 Standard-B plug
> � Captive cable with USB 3.0 Standard-A plug
> � Permanently attached cable with USB 3.0 Micro-A plug
> � Permanently attached cable with USB 3.0 Powered-B plug
> A captive cable is a cable assembly that has a Standard-A plug on one end and
> that is either
> permanently attached or has a vendor-specific connector on the other end. A
> permanently attached
> cable is directly wired to the device and it is not detachable from the
> device. This specification
> does not define how the vendor-specific connector or permanent attachment
> shall be done on the
> device side.
> For electrical compliance purpose, a USB 3.0 captive cable (permanently
> attached or with vendorspecific
> connector on the device end) shall be considered part of the USB 3.0 device.
> No other types of cable assemblies are allowed by this specification. Section
> 5.5 provides detailed
> discussion on USB 3.0 cable assemblies.
This also points out why us fogeys need to read the latest specs. USB
3.0 allows a USB 3.0 Standard A to USB 3.0 Standard A cable:
> 5.5.2 USB 3.0 Standard-A to USB 3.0 Standard-A Cable
> Assembly
> The USB 3.0 Standard-A to USB 3.0 Standard-A cable assembly is defined for
> operating system
> debugging and other host-to-host connection applications. Table 5-10 shows
> wire connections for
> such a cable assembly. Refer to Figure 5-16 for the USB 3.0 Standard-A plug
> cable overmold
> dimensions.
The usual D+/D- pair, inherited from the USB 2.0 spec, are not connected
in the cable; only VBUS and GND are connected in the legacy pins. All of
the Superspeed pins are connected in what looks like a crossover
configuration.
USB 2.0, the prior spec, does not:
> 6.4.4 Prohibited Cable Assemblies
> USB is optimized for ease of use. The expectation is that if the device can
> be plugged in, it will work.
> By specification, the only conditions that prevent a USB device from being
> successfully utilized are
> lack of power, lack of bandwidth, and excessive topology depth. These
> conditions are well understood
> by the system software.
> Prohibited cable assemblies may work in some situations, but they cannot be
> guaranteed to work in all
> instances.
> � Extension cable assembly
> A cable assembly that provides a Series �A� plug with a series �A� receptacle
> or a Series �B� plug
> with a Series �B� receptacle. This allows multiple cable segments to be
> connected together,
> possibly exceeding the maximum permissible cable length.
> � Cable assembly that violates USB topology rules
> A cable assembly with both ends terminated in either Series �A� plugs or
> Series �B� receptacles.
> This allows two downstream ports to be directly connected.
> Note: This prohibition does not prevent using a USB device to provide a
> bridge between two USB
> buses.
> � Standard detachable cables for low-speed devices
> Low-speed devices are prohibited from using standard detachable cables. A
> standard detachable
> cable assembly must be high-/full-speed. Since a standard detachable cable
> assembly is high-/fullspeed
> rated, using a long high-/full-speed cable exceeds the capacitive load of
> low-speed.
So, I'd say that A-A cables are allowed, but only useable between hosts
with USB 3.0 Standard A sockets. Devices with USB 2.0 Standard A sockets
still need a cable with a bridge device.