Subject:
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Re: Sharp GP2D12 (analog version) troubles
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 30 Nov 1999 23:31:59 GMT
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Original-From:
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Gary Livick <glivick@pacbell.(ihatespam)net>
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Viewed:
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996 times
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Terry,
I posted this awhile back.
Somebody asked the other day about a problem interfacing the Sharp
GP2D12. I didn't see an answer, and I just did it myself and solved the
problem, so here is how to do it.
For those who don't know, Sharp just came out with an IR ranging sensor
good out to about 30 inches that provides an analog signal related to
range. The signal is not linear, but that can be dealt with in
software. The area examined by the sensor is very narrow, so by
mounting it on a small servo and sweeping it while gathering range data,
a lot if information can be obtained about the immediate surroundings.
The GP2D12 has a few advantages over sonar; 1. it is good down to about
5", 2. it is less than $15.00, 3. it refreshes about every 32 ms, and
4. it does not require a driver, you just plug it in and start reading
data.
Hooking it up has one small gotcha with the HandyBoard and probably most
of the other MIT-spawned boards as well. The output of the sensor wants
to see a floating pin, but the analog inputs on the HandyBoard are
pulled high by RP3, a 47k resistor pack. To connect the sensor to the
HandyBoard, you have to cut a trace so the input can float on that pin.
That is easy enough to do, as the traces on the main board are easy to
identify, and easy to repair if you change your mind later and want to
restore the pin to normal. However, some care must be taken to choose a
pin for an input. If you just cut a trace for a pin at random, due to
the way the circuit is layed out you may just isolate the input pin from
the HC11 instead of removing the pull-up voltage. Unless you want to
figure out what I'm talking about, use analog 5 to connect your GP2D12.
Trimming the trace between RP3 and that pin has the anticipated result.
The sensors are available at http://www.acroname.com Check out some of
my robots in the gallery while you are there.
Gary Livick
Terry Gathright wrote:
> Hello Alex,
> I ordered two GP2DO2's from www.acroname.com a while back that worked great
> and am currently ordering two GP2DO12's. Sorry that I cannot help solve
> your problem now but please post the solution for the mail list when someone
> responds.
> Thanks,Terry
> -----Original Message-----
> From: Alex Stewart <robotman5@hotmail.com>
> To: handyboard@media.mit.edu <handyboard@media.mit.edu>
> Date: Tuesday, November 30, 1999 4:00 PM
> Subject: Sharp GP2D12 (analog version) troubles
>
> > Hi
> > Recently Got a sharp Gp2D12 IR ranger , for those who dont know it
> > continusly gives a analog value in proportion to the distance to a object.
> > Problem: When I wired it up I got a constant 147-150 no matter were the
> > object was. Unplugged sensor I got 2?? so I know the port works. Any Ideis?
> > Could it be the 47k pull up? I heard it could be , and to fix you cut the
> > trace for one of the ports top disable the pull up, but which one ?? tried
> > cutting analog 6 but then analog 6 wouldnt work? Help
> >
> > Thanx
> >
> > Robotman
> >
> >
> > P.S. Resolderd little gap I cut and analog 6 was restored.
> > Is there a web site with answers to above?
> >
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Message is in Reply To:
 | | Re: Sharp GP2D12 (analog version) troubles
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| Hello Alex, I ordered two GP2DO2's from www.acroname.com a while back that worked great and am currently ordering two GP2DO12's. Sorry that I cannot help solve your problem now but please post the solution for the mail list when someone responds. (...) (25 years ago, 30-Nov-99, to lugnet.robotics.handyboard)
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