Subject:
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Re: Gp2D12 Distance Sensor interface to RCX
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 19 Oct 2001 20:26:12 GMT
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Viewed:
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1852 times
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about 3 times a second is fine, for most applications. A continous power
option would be handy sometimes.
If I remember right the 50ms, is the charge time required for the cap to get
to power to activate the gp2d12, not for it to actually startup and take a
reading. Am I correct in that? If so, with external power we could still
only power one at a time and track faster.
Or if I am wrond about that, power one ahead of current sensor. That would
makes it 6x a second. Probably overkill withm 7 sensors.
How about tying the same sensor to more than one mux port, so that if you
had a couple critical ones and a couple less critical ones you good stagger
them?
In lugnet.robotics, edwards@cs.vt.edu writes:
>
> Instead, one can use a module that supports 7 (say) GP2D12's. Only
> one is active at any given time. The module has a built-in counter,
> triggered from the RCX by toggling the sensor port from passive->active->passive
> or something, as well as an analog multiplexer to route the selected
> sensor's signal back to the RCX. It would also be nice to only apply
> power to the selected sensor, as well.
>
> Now the RCX "sensor monitoring" task simply has to run a loop that
> toggles the sensor port to advance to the next GP2D12, sleep for
> 50ms, read and store the sensor port value, then repeat.
>
> All sensor values (stored in variables on the RCX) could be accessed
> at any time by the remainder of the program, and each individual value
> would be updated just under 3x each second.
>
> Hardware for this does not seem terribly difficult when the problems
> of cycling/remembering are pushed off to the RCX. If external power
> were used for the module, it would also be easy to allow jumper-selectable
> continuous duty/vs. one-at-a-time power to all 7 GP2D12's. This would
> support faster update cycles (by changing the timing of the monitoring
> task in the RCX) at the cost of more power consumption.
>
>
> -- Steve
>
> --
> Stephen Edwards 604 McBryde Hall Dept. of Computer Science
> e-mail : edwards@cs.vt.edu U.S. mail: Virginia Tech (VPI&SU)
> office phone: (540)-231-5723 Blacksburg, VA 24061-0106
> -------------------------------------------------------------------------------
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Message has 1 Reply:
 | | Re: Gp2D12 Distance Sensor interface to RCX
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| The 50 ms period _IS_ the startup time of the GP2D12 itself, and the time interval between two distance measurements. See oscilloscope trace (top of page): www.philohome.com/se.../scope.htm Philo (...) (25 years ago, 20-Oct-01, to lugnet.robotics)
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Message is in Reply To:
| | Re: Gp2D12 Distance Sensor interface to RCX
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| (...) Sounds like you have a fairly good idea of how you want to use it, and it all makes sense. The hardware can be simplified quite a bit if this is the typical usage pattern, though. (...) Since the RCX is already storing the values for use by (...) (25 years ago, 19-Oct-01, to lugnet.robotics)
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