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X-"Aleph One Ltd"-MailScanner-From: steve@steves-house.org.uk
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On Wed, 22 Jun 2005 15:46:38 +0100, David Bisset
<
david_bisset@btconnect.com> wrote:
> From this I assume that the New Balloon generates 5v (for USB etc)
> on-board?
There's certainly no step-up/step-down section dedicated to providing 5V,
no. At the moment, we just switch VDD_RAW onto the USB, if called for.
> If not then this probably ought to be 5ish.
Yep, that's the plan, if you want to be a USB master.
> I certainly power the Balloon via the Samtec and not the other way
> round. So
> I would be feeding 5vish into these pins.
That's fine.
> Can we clarify the function of the following signals:
>
> RUN_NAND - Do we need it?
Maybe. We need to be able to power down the NAND chips if we want them to
kick into any magic boot modes. Not sure anybody cares any more. I'm
definitely not sure it belongs on the backplane. It used to be there to
allow (yet) more NAND on the backplane - does anybody do this? (Guralp?
Where do they attach their infinite quantities of storsge?)
> NAND_RNB - Originally internal to Balloon2, therefore should just revert
> to
> GPIO.
Nick? How do you detect NAND readiness these days? Backplane question as
above.
> SAMOSA_ABSENT - What does it mean, a SAMOSA device is plugged in, or is
> powered and working? Why do we need it since the SAMOSA bus isn't on the
> backplane (and doesn't need to be).
Yeah, I think this doesn't belong on the backplane. It's appropriate for
the Samosa bus, though, since that's where I'd want to hang a SM socket,
if needed.
> NSLEEP - This used to be a very hardware signal that shut off the 5v
> switcher, it is now connected to GPIO so cannot fulfil its original
> function. Should this become GPIO or is there a real "TURN IT ALL OFF"
> signal that this should be connected to. (Having said this I've never
> used
> it).
Hmm. I've not pondered power management across the backplane at all. I
guess we ought to expose sme of the PXA's power sequencing pins.
Steve
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