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X-"Aleph One Ltd"-MailScanner-From: chris@martin-jones.com
Cc: 'Steve Wiseman' <steve@steves-house.org.uk>, balloon@balloonboard.org
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David Bisset wrote:
> From this I assume that the New Balloon generates 5v (for USB etc) on-board?
> If not then this probably ought to be 5ish.
> I certainly power the Balloon via the Samtec and not the other way round. So
> I would be feeding 5vish into these pins.
Good point - I'm not sure where 5V for USB is coming from, other than
VDD_RAW which isn't very nice. Having said that, TCL use USB slave
powered by 3.3V and it seems to work...
> Can we clarify the function of the following signals:
>
> RUN_NAND - Do we need it?
Possibly not. It was just the nearest functionally equivalent signal to
what was there before, in case anyone depended on switching something on
when the NAND was enabled. Unlikely, I agree.
> NAND_RNB - Originally internal to Balloon2, therefore should just revert to
> GPIO.
This is fair enough. Can't see anyone using it.
> 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).
It's the equivalent of the old SM_ABSENT signal which indicated that
there's no SmartMedia card inserted. The current Samosa in the kernel
uses it to decide whether to make /dev/samosa_bus available, which it
does if there is no SmartMedia card inserted. Again, this is just a
hangover from the previous design and might be more useful as an
uncommitted GPIO.
> 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
This is still a very hardware signal that puts the ARM switcher into LDO
mode - the ARM asserts it when it wants everything to be as low power as
possible but still wake-up-able. That was my logic for putting it there,
since the 5V switcher no longer exists. I thought it might be useful for
indicating to motherboard devices or external power management that they
really, really should go low-power. I guess it's become a source rather
than a sink, which is awkward, but if nobody's used it, this may not matter.
Chris
--
Chris Jones -
chris@martin-jones.com
Martin-Jones Technology Ltd, makers of Solidlights
148 Catharine Street, Cambridge, CB1 3AR, UK
Phone +44 (0) 1223 474968 Fax +44 (0) 870 112 3908
http://www.solidlights.co.uk/
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