Re: disable VBUS?

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On Mon, 7 Jul 2014, Steve Calfee wrote:

> You are right, the device will get 5 volts. However it is still part
> of the spec that 2ms without a SOF will force the device into suspend
> mode, so it will use less than 2ma. So depending on your definition of
> function, there will be power, but no activity. If it uses more than
> 2ma, from the bus, problems will ensue.

What you're saying is true, so long as the spliced USB cable isn't 
plugged into a host.  But of course, you wouldn't expect to get any 
activity on a device when it isn't plugged into a host -- even if you 
use a normal cable.

If the spliced USB cable _is_ plugged into a host then the host will
see it, issue a reset, and start sending SOF packets.  In that
situation your comment doesn't apply.

Alan Stern

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