freerunner: charging and usb-host mutually exclusive?

joerg joerg.twinklephone at
Wed Mar 12 04:18:22 CET 2008

Am Mi  12. März 2008 schrieb Brad Midgley:
> joerg,
> >  Ah, i see a Y-adapter: one end usb-device, one end receptable for usb 
> >  one end GTA02 *with ID-R of e.g 82k* PLUS *2 x 15k pulldown*.
> >  And GTA02 automatically switching to external powered host mode. :-)
> >  This was on the list of accessories from the beginning, wasn't it? ;-)
> >
> >  humm, on 2nd thought, nothing bad will happen when this mode will check 
> >  47k instead of 82k.
> I want to make sure (as long as it's not premature) that we capture this in
> I can follow the need for pulldowns on d+/d- but where did 82k come
> from? How does your comment about 47k fit in?

82k was just a fantasy-value i introduced to identify the jr(C)-Y-adapter. 
There's a 47k (from usb-id to GND) specified for identifying the 
OM-fastcharge-usb-adapter, to enable >500mA USB supply handling for 
turbo-charge (see my post here in this list some days ago, as well as 
wiki/charger something)

However there's no need at all to identify the Y-adapter by it's own 82k 
value, it's just fine to switch to host&ext-power mode whenever NEO sees the 
47k in ID-pin, which is specified for GTA02 aka Freerunner usb-charger. If 
there is 47k, it's either the plain charger (= no device and no real usb at 
all, ext-power hostmode won't hurt), or we have charger PLUS Y-adapter, which 
is fine for external powered hostmode, which means you can connect devices to 
NEO-host and still supply power to these devices (about 1,5A for Freerunner's 
2,5A charger) AND the NEO (about 1A for Freerunner's 2,5A charger) via 
In the end this means: the 47k ID-R should be in the Y-adapter, and you may 
use arbitrary usb-chargers (>1A) with it for quick-charge. However the 
OM-charger will most probably have an own 47k, so you can use it without the 
Whenever Y-adapter or OM-charger is connected, Freerunner enters externally 
powered USB-host mode and starts quick charge. On device end of Y-adapter you 
may use an unpowered USB-hub, which is powered via charger and usb.

Once i see a wiki page, i might eventually provide a (however trivial) circuit 
diagram, as soon as i reanimate my eagle layout suite underneath the dust if 
7 years ;-)

Premature? It's clean, just missing the (kernel)patch to handle 47k detection 
and switching to ext-powered host mode automatically. Andy said he will 
provide the patch. I'm quite sure these hw-details won't change for GTA02 
Mass Production. I'll start tomorrow to sell these jr-Y-adaptors for 19,95€ + 
shipping ;-)


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