Y-cable and USB-OTG: mutually exclusive / the four connectivity solutions

joerg at openmoko.org joerg at openmoko.org
Thu May 1 22:52:33 CEST 2008

Am Fr  2. Mai 2008 schrieb Werner Almesberger:
> How do we feed the JTAG/console subsystem ? From a Vsys combined from
> all three possible sources, or from the USB-debug 100mA path ?

Andy wrote:
> Joerg wrote:
> | Q- Talking about power to debug-USB: should we power the FTDIchip and
> | his team by debugcon-Vusb only (using U3, or something less
> | sophisticated), so it doesn't take any power while no connection to
> | USBdbg? Are we sure FTDIchip will show the behaviour we need regarding
> | GPIO-Z|gentle-pulldown etc, while powered down? Or do we need to
> | maintain power to debug circuitry all the time, to have the states we
> need.
> If we can power it from host USB power it will solve most of the problem
> of it taking current in normal use.  But then we need to take care about
> not driving high levels into it from main board when it has no local power.


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