Subject:
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Re: A Generic Idea
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Newsgroups:
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lugnet.robotics
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Date:
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Sat, 4 Jan 2003 20:07:43 GMT
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Original-From:
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Steve Baker <sjbaker1@airmailAVOIDSPAM.net>
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Viewed:
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625 times
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Andy Gombos wrote:
> I didn't really think about text messaging - pressing buttons multiple times
> to enter code words could get tricky.
Yes - but these are computers - they can send each other messages in binary -
you only need two buttons really. Dunno how a computer could recieve text
messages though. Email would be better...but still very slow.
> I was thinking more along the lines of using the RCX's builtin beep codes -
> though I just realized that wouldn't be very practical or effecient. If
> this is all for communicating to the computer, dialing the modem and getting
> a DSP (or whatever chip they use to create the DTMF tones) chip to interface
> with it would probably be the easiest.
You can't generate DTMF tones with the RCX because the 'DT' of DTMF
stands for "Dual Tone" - telephone buttons send two audio frequencies
at once (one says which row of the keypad is being pressed and the
other which column so that together, the dual tones uniquely specify
which keypad button is being pressed).
Furthermore, the DTMF reciever is pretty picky about the
frequencies and wave forms - you have to be reasonably precise when
sending DTMF pulses.
If you are going to add electronics to the RCX, the simplest solution
is probably to use a second microprocessor - there are several single-chip
devices that can generate and recieve modem tones at 9600 baud or so.
That's about 300 times faster than a DTMF signaller can go. (IIRC,
DTMF tones have to be more than 1/10th second long to be reliably detected
- so 10 decimal digits per second would be the absolute fastest you could
go. That's less than 30 baud!)
If you are going to those lengths - you are probably better off making
your own digital radio link.
---------------------------- Steve Baker -------------------------
HomeEmail: <sjbaker1@airmail.net> WorkEmail: <sjbaker@link.com>
HomePage : http://www.sjbaker.org
Projects : http://plib.sf.net http://tuxaqfh.sf.net
http://tuxkart.sf.net http://prettypoly.sf.net
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Message has 1 Reply:
 | | Re: A Generic Idea
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| Thanks for all the modem input guys, but I think you're getting too ambitious! The communication I was thinking of would consist of maybe dialling+10 button presses on the cel phone. The other end would be waiting for these combinations, just like (...) (21 years ago, 5-Jan-03, to lugnet.robotics)
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Message is in Reply To:
| | Re: A Generic Idea
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| (...) email (...) I didn't really think about text messaging - pressing buttons multiple times to enter code words could get tricky. (...) I was thinking more along the lines of using the RCX's builtin beep codes - though I just realized that (...) (21 years ago, 4-Jan-03, to lugnet.robotics)
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