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4647  |  4649
Subject: 
Re: IR Detection
Newsgroups: 
lugnet.robotics.handyboard
Date: 
Mon, 2 Nov 1998 02:12:16 GMT
Original-From: 
Darkman <{lroska@}StopSpam{cyberus.ca}>
Viewed: 
1961 times
  
Hi

Most of the IR LED's sold at Radio Shack are the 840-880 nm wavelenght type.
The Sharp tin can requires the 940 nm wavelength IR beam if my memory serves
me right, it also requires to be modulated at 38 or 40 kHz depending on the
model. This 38 or 40 kHz should  also be modulated on and off to get a
response from the sensor.

I currently have the IRPD http://www.robotstore.com/ hooked up to my Handy
Board  and have good results.
If you go that way let me know and I 'll send you some code in c.

I hope that helps and correct me if I'm wrong!



-----Original Message-----
From: Rajbala Makar <makarraj@cse.msu.edu>
To: handyboard@media.mit.edu <handyboard@media.mit.edu>
Date: Thursday, October 29, 1998 8:43 PM
Subject: Re: IR Detection


Hi Everyone:

I am trying out the infra red emission and detection with
the Handy Board. I have succeeded in the emission part
but the detection circuit is not working. I know that
the emitter LED is fine , with the help of Radio Shack
Infrared sensor card. can anyone give me any hints as
to how to get the sharp detector to see the radiations
or maybe do it with the help of any other detector also.

The Sharp IR detector is designed to respond only to modulated IR • signals.
The card from Radio Shack will indicate whether the LED is illuminated,
but it won't tell you whether it's modulated at the proper frequency.
Perhaps that could be the problem?  Just a guess.  Good luck!

--Will

Hi Will:

What you say might be the reason for my problem hence I bought a
matched IR emitter and detector pair from Radio Shack and tried the
same thing. Here again, the emitter is sending the signal but
the detector is not able to see it. I tried connecting the receiver
to a digital port directly without any resistor and analysing the
input from the port by using the digital(int) function. It did not
show any level change. Basically, I am trying to
implement something similar to the REC 80 routines by Danny Negro
and Max Davies' work. I hope to be able to transmit the codes
from the IR transmitter of one handyboard and have another HB
receive and decode the signals. I even tried Sriram's code  (I got
it from the HB mailing list archives ) which
sends out a signal similar to that sent out by the sony remote but
the Sharp Chip was still not able to receive/decode it.
Another question I have is, if I want my handyboard to send signals
in different directions, do I need to have as many detectors as
emitters or one detector will do?

Thanks for your help.

Raj.




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