Even though this might violate the spirit of the specification, it is highly likely this will work. Most PCBs that use differential signals are very loosely coupled by the nature of the traces having to be side by side. The traces can wander quite a bit and still maintain a reasonably close differential impedance. The more important aspect is to maintain a matched distance. Depending on which speed of USB that you want support for, this can easily be achieved even going through a header - as even this doesn't have to be that precise. Consider this, just about every motherboard in existence has USB port headers to go to a ISA/PCI/PICe slot connector. All of these go to a ribbon cable with two insulation displacement connectors - one at each end. These surprisingly work well for most PC users - go figure - even with all the changes in impedance. I suspect a 1/2" or so header won't be as much of a challenge. Doesn't sound like Gerald has any intention to make this change anyway, but if someone wanted to try this as an option for their own board, with planning, it should be workable.
On Monday, April 14, 2014 4:06:46 AM UTC-5, john3909 wrote: > > > On 4/13/14, 8:52 AM, "[email protected] <javascript:>" > <[email protected]<javascript:>> > wrote: > > >I have to say that USB connection accesible from the side headers would > >be really nice feature. I aggre that you can loop a regular usb cable, > >but this way makes ot more robust and that just doesnt look good. Imagine > >someone buildibg a device basing on bbb. Everything could be connected to > >the cape and all a worker has to do is place the bbb on the cape. > USB uses differential signaling with controlled impedance. The connectors > used for the capes would violate this specification and cannot support USB > signaling. > > Regards, > John > > > > > >I vote for this as well ;) > > > >-- > >For more options, visit http://beagleboard.org/discuss > >--- > >You received this message because you are subscribed to the Google Groups > >"BeagleBoard" group. > >To unsubscribe from this group and stop receiving emails from it, send an > >email to [email protected] <javascript:>. > >For more options, visit https://groups.google.com/d/optout. > > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
