Subject:
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Re: Interfacing a STAMP
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 1 Jan 1999 02:23:37 GMT
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Viewed:
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1406 times
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lego-robotics@crynwr.com wrote:
> Ok I did it. I took another look at how to get a BASIC STAMP to talk to an
> RCX. They can talk through the ports digitally. This would be inefficient.
> The STAMP only has 8 I/O lines, the RCX has only three. You could
> theoretically decode 8 inputs with three signals, but then the STAMP would
> only have 5 I/O lines left.
>
> The STAMP is capable of transmitting up to 2400 BAUD serially. There is an
> application note available at Parallax (the maker of the STAMP) that shows how
> to wire an IR transceiver using easy to find inexpensive parts. The only
> problem here is that the application note states that at 2400 baud, there is a
> high probability of errors due to the way the STAMP interprets the start bit.
> I might build it any way, just to see for myself.
>
> Finally, the STAMP can output voltage through a command called PWM - pulse
> width modulation. It requires a capacitor and a resistor on the STAMP end and
> the four diode, one resistor analog interface on Gasperi's wep page.
>
>
> input port (RCX)
>
> |
> 1 micro farad
> +--|<---+--->|-------+
> STAMP ---->pin7---[10k]---| (------+------------[2.2K]----|
> |-----gnd
> |
> +--|<----+--->|------+
> gnd
> |
>
> input port (RCX)
>
> STAMP PROGRAM - test if pin 0 is low. If it is, output ~2.5 volts else output
> 5 volts
>
> DIRS=%00000000 'set all pins to input
> loop: if pin0=0 then p0 'trap pin 0 = low
> b3=0 'set volt = 0
> goto volt
> p0: b3=128 'set volt to ~2.5v
> volt: pwm 7,b3,255 'output PWM on pin7 for maximum number of
> 'cycles
> goto loop
>
> I found that if run this and hook up the STAMP, with pin 0 high, the RAW value
> is 660, with pin 0 grounded it is 883. The important thing is that the values
> are stable within a point or two.
>
> chris
> --
> Did you check the web site first?: http://www.crynwr.com/lego-robotics
If you could just offload some tasks and use the stamp for additional sensors it
would be worth doing.
maybe you could set up a a/b switch to go from ir to hardwire, since the ir is only
used during programming anyway.
-- Bobby
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Message is in Reply To:
 | | Interfacing a STAMP
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| Ok I did it. I took another look at how to get a BASIC STAMP to talk to an RCX. They can talk through the ports digitally. This would be inefficient. The STAMP only has 8 I/O lines, the RCX has only three. You could theoretically decode 8 inputs (...) (26 years ago, 31-Dec-98, to lugnet.robotics)
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