Subject:
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Re: Sensor monitoring
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 26 Jan 1999 01:31:02 GMT
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Viewed:
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1309 times
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lego-robotics@crynwr.com (Paul Haas) writes:
> On Wed, 20 Jan 1999, Michael Gasperi wrote:
>
> > I think the sensors are read every 3ms and the value stored somewhere.
> > I don't think they are read just when you ask for them in software.
> > You get the last value read. I base this on the way the rotation
> > sensor and some of the sensor modes work. They would require a
> > separate background task to process. Two readings would never be at
> > the exact same time. I would guess that sensor 1 is always read just
> > before sensor 2.
>
> The H8 object code reading crowd may know for sure. Those of us with dual
> trace oscilliscopes can also figure it out. An oscilliscope can show when
> a port in light sensor mode is being read. With a dual trace scope we can
> see if the sensors are read almost simultaneously, separated by a
> millisecond, separated by 100 microseconds or some random interval (not
> likely).
>
> I and several other reported months ago that the light sensor is powered
> for 3 milliseconds then read for 100 microseconds. On further reflection,
> I suspect it's really powered for 2.9 milliseconds and the whole cycle is
> 3 milliseconds long. I must read Kekoa's page, it's probably already
> there.
I got around to looking at two inputs at the same time with a dual trace
scope. All of the inputs go into the 5V read at the same time! That doesn't
say they are read by the uP at the same time, but the switch between power and
read and back is made for all the sensors at the same time. I would have
thought it would be a sequential thing also. I can't tell 100us out of 3ms
well enough to say if it is a total of 3ms or 3.1ms.
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Message is in Reply To:
 | | Re: Sensor monitoring
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| (...) The H8 object code reading crowd may know for sure. Those of us with dual trace oscilliscopes can also figure it out. An oscilliscope can show when a port in light sensor mode is being read. With a dual trace scope we can see if the sensors (...) (26 years ago, 21-Jan-99, to lugnet.robotics)
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