Subject:
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Re: Date/Time Clock for NXT?
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Newsgroups:
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lugnet.robotics.nxt
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Date:
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Thu, 30 Nov 2006 21:26:20 GMT
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Viewed:
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13516 times
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Hi Dick,
"Dick Swan" <dickswan@sbcglobal.net> writes:
>
> A date/time clock would be a useful addition to the NXT. Naturally, it
> should continue to operate even when the NXT is powered "down". So
> here's a question for any hardware gurus that have a good
> understanding of the NXT schematic.
>
> The ARM processor on the NXT has a low power mode where it can be
> powered off except for a small portion contaiining a real-time clock
> (RTC). I think you can configure the ARM into a very low power mode so
> that the RTC clock continues to operate and can periodically wake up
> the rest of the processor via an interrupt. I think this might be all
> that is required to implement a date/time clock that can be
> continuously updating even when NXT is powered down; the NXT would
> wake up every few seconds to perform a few microseconds of work to
> update the clock variable and then go back to sleep. Powered down mode
> would be redefined to mean "set the ARM CPU to a low-power state where
> RAM and RTC are still powered on but CPU is inactive".
that is all less than crystal clear from the AT91SAM7S data sheet,
but plausible.
> In particular, I suspect that the NXT may have circuitry
> controlled by the 8-bit AVR processor that disconnects all
> power to the ARM CPU so that you can't set the ARM into a
> low-power state. Anybody able to answer this question?
I think so, too. On page 2 at the left there is the circuit
which generates VCC3V, and it is controlled by the AVR via P_EN.
The 1.8V for the core is presumably generated by the AT91 itself
from the 3V (it can do that, and there is no other circuit for it),
and I don't see any other power than VCC3V going into the AT91.
It would be nice if I were wrong
Jürgen
--
Jürgen Stuber <juergen@jstuber.net>
http://www.jstuber.net/
gnupg key fingerprint = 2767 CA3C 5680 58BA 9A91 23D9 BED6 9A7A AF9E 68B4
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Message is in Reply To:
 | | Date/Time Clock for NXT?
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| A date/time clock would be a useful addition to the NXT. Naturally, it should continue to operate even when the NXT is powered "down". So here's a question for any hardware gurus that have a good understanding of the NXT schematic. The ARM processor (...) (18 years ago, 30-Nov-06, to lugnet.robotics.nxt)
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