Fast charging and the resistor trick

Sven Klomp sven at
Fri Mar 6 10:11:27 CET 2009


I have a microcontroller based USB device and want to connect it to the 
Freerunner (in host mode). Now I need some clarifications on the resistor 

The two 15k Ohm resistors are indispensable to comply with USB-spec?
What will happen if I connect the device (with the resistors) to the USB port 
of my computer? (The external power supply is turned of)

How do I have to design the USB endpoints on the device, so the Freerunner 
does charge with 1A? Or do I need the 47k Ohm resistor if the FR is in host 

it is written that "Future kernels should switch to hostmode + external power 
when seeing this 47k resistor." Is this already implemented?

Furthermore, it is mentioned that the resistors can be used to avoid suspend 
of the Freerunner. I hope, I still can suspend if I want?

Thanks for your help

P.S.: If you wonder, what are my plans, have a look here: :-)

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