Subject:
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Re: IR Subsystem confusions.
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Fri, 28 Mar 1997 00:14:36 GMT
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Original-From:
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Sriram Tirunellayi <sriram@ds5500.cemr.wvu.edu%avoidspam%>
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Viewed:
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1520 times
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>
> What was/is the purpose of the IR Subsystem on the Handy board.
The handyboard consists of an IR transmitter and detector circuits.
The purpose of the transmitter (when connected thru the infrared LED) is
to produce infrared light waves at particular frequencies. This frequency is
controlled by R4 and C6 (refer to Fred's transmitter circuit diagram)
and typically is set at 38KHz. Moreover they can be modulated by
software control (see set_ir_transmit_frequency() function).
The purpose of the detector circuit is to detect modulated infrared
signals. The transmitter and detector can be used in tandem to detect
obstacles (obstacle avoidance), speed of your robot (shaft encoder) or
any other application that you can think of....
>
> What is the difference between the Sharp Demodulator and the one you get
> from Radio Shack.
iam not sure about what radio shack has..
>
> How do you use the onboard IR demodulator as a digital input.
the following loop can be used to see if the IR demodulator has sensed
any obstacle/object..
for(i=0;i<3;i++)
{
bit_set(0x1000,0x40); /*turns LED ON for 600microsec*/
sleep(0.0006); /*the sharpIS1U60 i.e. the onboard needs a
burst wave in the range 400-800micro sec*/
val_on = peek(0x1000);
bit_clear(0x1000,0x40) /* turn LED OFF */
sleep(0.0006);
val_off = peek(0x1000);
if( (val_off & ~val_on & 4)==4) hit = hit+1;
else hit = 0;
}
if(hit==3) printf("obstacle detected");
else printf("nothing detected");
>
> Are there different kinds of IR Emiiters.
>
>
LED emitters differ in their peak output power and output angle.
The intensity of light can be controlled by connecting a resistor in
series with the LED. You can collimate to obtain a narrow range of
emission.
hope this helps
Sriram
> Thanks
>
> victor
>
>
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