Y-cable and USB-OTG: mutually exclusive

Werner Almesberger werner at openmoko.org
Wed Apr 30 20:46:08 CEST 2008

Joachim Steiger wrote:
> indeed. i also see nothing which stands in the way of having the usb-b
> do all what otg needs on a electrical/protocol level when the soc does
> all that for us.

Hmm, so you're saying you'd still do OTG as well ? I think doing OTG
on a mini-B port, would put us rather deep into "weird cable" hell.

> when usb HOST is failing you can still debug that via ssh over the
> usb-client mode/charger port (or kernel-gadget from cdc-ethernet to
> cdc-adm ;))

Yeah, unless the kernel blows up. Then its last gasps will still be
in some URB, never to be seen by the PC. Of course, we can just do
as we do on PCs, and display thing on the LCM.

> yes. but its only usb1.1 12mbit, not the 480mbit otg capable usb which
> will go through the switch/switched latch so this should be doable
> without too much hassle.

Hmm, only Full-Speed in host mode isn't so great. E.g., if you want
to backup to some external storage, you'd hate that quickly.

> i bet even a stone-old cmos 4066 latch would do.

With Ron = 270Ohm at Vdd = 5V ? You may be pushing your luck ;-)

- Werner

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