Y-cable and USB-OTG: mutually exclusive

Werner Almesberger werner at openmoko.org
Tue Apr 29 14:43:39 CEST 2008

Joerg Reisenweber wrote:
> When I asked this question, either Raster or Harald tld me, we're even
> going to pay quite some money for it.

Oh, that's interesting. So far, we didn't care about giving the man wads
of money to be patted on our head for how nicely conformist we are ;-)

> Nope! :-)

One wart down :)

>> By the way 2: drawing power from debug-USB also needs charger detection
>> and a current limiter for 100mA vs. real power.
> Right. Never will happen, FTDI chip can't do this I think. :-((((

It doesn't have to. All we need is some ADC that can probe what's going
on there.

> So we're back again to my lovely little coax ;-) Much smaller than 2nd
> micro-USB, much simpler, many many compliant chargers out there.

And people will plug in a lot nastier stuff as well ...

With USB, you at least know that it'll be roughly 5V, DC, not too evil
spikes, polarity is right, etc.

- Werner

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