Y-cable and USB-OTG: mutually exclusive

Joerg Reisenweber joerg at openmoko.org
Tue Apr 29 10:11:21 CEST 2008

Andy Green schrieb:
> Somebody in the thread at some point said:
> Just saying that if the debug USB connector can do double duty as
> "adapter power" that makes everyone happy.  It doesn't have to be in a
> place that stops thing lying on desks.
> | Confusion of end-user by 2 identical connectors, one of them, the really
> | hard to find one, for (virtually everyday) power for host mode and
> | useful for nothing else but (highly sophisticated) debug, the other for
> | power *only* when not in OTG-mode, but you can do everything else with
> | it... :-/
> | My 0.02EUR: A no-go, a no-NO-go. The appeal of simplicity of a coax
> | power connector you probably find 10000 times more "chargers" for it
> | everywhere in he world than for USB (e.g. my old nokia charger), you
> | simply can't beat that.
> Power isn't the only consideration, we already thought about bringing
> out debug USB connector to the outside world.  If that is what we do,
> then it is sitting there ready to eat power the same as the OTG
> connector, and it makes sense to allow it.  

And we lose our USB-OTG cert, which clearly states certified devices
have to have "one, and *only* one, micro-USB-AB-receptacle" [2006-12-05
USB-OTG supplement rev_1.3, §3.2]. As we may expect this doesn't apply
for internally only accessible debug-connectors, it surely will hit us
with two (identical!!!) external USBcon.

> It is a built-in solution
> for what the Y cable is proposed to do.

That's what I meant by saying "no more need for Y-cable"

> Confusion can be managed by recessing the connector slightly, putting it
> somewhere less obvious, marking them


> etc.  But it will need
> to be managed.

Confusion of the USB-cert-auth won't be manageable anyway ;-)
Probably there is some reason for the coax connector for power on the
N800 Nokia. They contributed on the OTG specs.


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