Subject:
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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 15:31:36 GMT
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Viewed:
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13118 times
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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 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".
I don't understand the NXT hardware / schematic well enough to know
whether this is possible. 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?
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Message has 2 Replies:
 | | Re: Date/Time Clock for NXT?
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| In article <J9Jv4v.nDo@lugnet.com>, Dick Swan <dickswan@sbcglobal.net> writes (...) This question seems straightforward. In the hardware schematic PDF that Lego have published there is a block diagram of the "Power Block" on page 4. This does indeed (...) (18 years ago, 30-Nov-06, to lugnet.robotics.nxt)
| | | Re: Date/Time Clock for NXT?
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| Hi Dick, (...) that is all less than crystal clear from the AT91SAM7S data sheet, but plausible. (...) 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 (...) (18 years ago, 30-Nov-06, to lugnet.robotics.nxt)
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