Subject:
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Re: Interfacing Sharp's GP2D02 Distance Sensor to the RCX
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Newsgroups:
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lugnet.robotics, lugnet.robotics.rcx
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Date:
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Sun, 21 Jan 2001 23:59:44 GMT
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Viewed:
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1493 times
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Ralf,
If you don't need great precision, an easier aproach might be my Infra-red Relative
Distance Indicator. See the link below.
http://home.flash.net/~sevcik/IRRD.htm
-pete.
Ralf Krause wrote:
> Hi,
>
> I asked this problem a few weeks (or months??? ... I don't know a what time
> ...) but nobody could help. I got the same following answer
>
> ".... the sensor takes 35 mA and this is to much for the RCX ..."
>
> but I couldn't understand this at this time. Until now since I really tried
> to connect my own sharp sensor GP2D12 to my own RCX. My thoughts were the
> same like anybody else (... or most of yours ...) thought about this problem
> ...
>
> Micheal Gasperi wrote that the sensor input has an active sensor mode and
> that thisone could drive an sensor power input with 8 volts ond with 30 mA.
> It's right that the RCX has 8 volts if you turn on the active sensor mode
> (that's the mode for the Lego light sensors or the Lego rotation sensors).
> But you can't get enough power to drive the GP2D12!!
>
> Therefor I 've done some tests with my RCX and a lot of resistors.
>
> --------------------------------------
> Table: RCX with new batteries (6 * 1.55 V = 9.3 V)
>
> R U I P = U * I
> ‡ V mA mW
> - 8.0 0.0 0.0
> 4700 7.5 1.6 12.0
> 2200 7.4 3.4 25.2
> 1000 6.5 6.5 42.3
> 820 5.5 7.9 43.5
> 680 5.5 8.0 44.0
> 560 5.2 8.7 45.2
> 470 4.5 9.3 41.9
> 330 3.5 10.5 36.8
> 220 2.8 12.0 33.0
>
> sensor type light sensor
> sensor mode Raw
> ---------------------------------------
>
> This table shows that its impossible to get 35 mA with the power of 5 V from
> the sensor input of the RCX. I think you can get 6 or 8 mA but then the
> power gets down.
>
> Yes, the RCX can drive motors with 100 or 200 mA but it can do so with its
> outputs and not with its inputs. If you want to drive a GP2D12 (or something
> else) you should do it with an output. If you only need to have two motors
> with your robot then yo have one output for driving your hungry sensors with
> electric power.
>
> Take four diodes 1N4148 or 1N914 for connecting the output to get correct
> polarised voltage. Then you need a 100 uF and a 78L05 and a 100 nF to get
> stabilized 5 V voltage for the sensors. With this interface you can really
> drive sensors with 100 mA or more. You program has to switch the output on
> with full power because setting smaller power would result pwm (power with a
> phase of power down ... and this is not dc power) at the output.
>
> And it 's nice to see the robot is stopping 20 cm in front the wall ...
> The GP2D12 is a distance measuring sensor with an infrared emitting diode
> and a signal prossessing circuit. It enables to detect objects without any
> influence on the color of reflective objects, reflectivity, the lights of
> surroundings.
>
> It has an output analog voltage with is detecting distances from 10 cm (3.1
> volts) to 80 cm (0.6 volts). I 've done the connection to the input of the
> RCX with the general purpose analog interface of Michael Gasperi ... the
> second one with the opamp.
>
> .../gasperi/gpa.htm
>
> Michael, please tell me how you can write that the power can " ... provide
> 30 mA of power to operate other sensor electronics." As I 've tested it
> seems that you can't do so ... or I am totally wrong ...??
>
> I hope to get a lot of questions and answers about this sensor problem and
> my tests ...
>
> Ralf
>
> ps
> Peter's creation needs two outputs, one for the power and the other for the
> handshaking protocol ...
> http://www.inchlab.com/gp2d02_interface.htm
>
> on 2001-01-12 00:41, John Barnes at barnes@sensors.com wrote:
>
> > Unless I am missing something here, the Sharp range of IR distance sensors
> > all have power consumptions in the 35mA range, which prohibits their use with
> > the RCX unless you resort to using external power packs.
> >
> > How do you propose getting around this problem?
> >
> > JB
> >
> > > In lugnet.robotics, Ram Meenakshisundaram writes:
> > > > Hi,
> > > >
> > > > Here is a link on how to hook up the GP2D02 to the RCX =
> > > > http://www.inchlab.com/gp2d02_interface.htm It seems to be overly =
> > > > complicated. Not to put down on Peter's creation as I think it was =
> > > > ingenious, but there must be a easier way to do this instead of =
> > > > compromising an input & an output port...
> > > >
> > > > Ram
> > >
> > > Hi Ram,
> > >
> > > I don't know an easier way of using GP2D02 but why don't you use the GP2D12
> > > instead ?
> > > It has an analog output.
> > > You don't have to analyze any serial protocol.
> > > And as the lego light-sensor has a driven light source, it should be
> > > possible to drive this sensor too.
> > >
> > > you can find a datasheet at :
> > > http://www.sharp.co.jp/ecg/NewProducts/sensor/gp2d12.pdf
> > >
> > > Rainer
>
> --
> ____________________________________________
>
> Ralf Krause
> Bertha-von-Suttner-Gesamtschule Dormagen
> Marie-Schlei-Strasse 6
> 41542 Dormagen
> Germany
>
> http://www.shuttle.schule.de/ne/bvsdormagen
> mailto:nospam.krause.ralf@web.de
>
> delete nospam. to get my real email address
> ____________________________________________
--
Pete Sevcik sevcik@flash.net
Techno-stuff Robotics
http://www.flash.net/~sevcik/
Robotics for FUN !
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