Subject:
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RE: decoding a message sent by an RCX
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Newsgroups:
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lugnet.robotics.rcx.nqc
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Date:
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Sat, 4 Sep 1999 19:13:48 GMT
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Viewed:
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2033 times
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Dave wrote...
> > I'm not used to seeing 8 bits with a parity bit, as a sanity check does this
> > mean that each byte is 11 bits (1 start, 8 data, 1 parity, 1 stop) - OR am I
> > misunderstanding this somehow. Since the RCX can send 0-255 as messages, I
> > THINK that I'm correct. Can someone set me straight on this?
>
> Yes, you are correct - 11 bits total per byte. And yes, this is very
> non-standard.
>
> I believe the signal is inverted - meaning that IR light is present for
> "0" bits, and no light for "1" bits. But I'm going from memory here and
> haven't looked at it on a scope for a long time so I could be wrong.
Remember, you can send arbitrary ASCII data using pbFORTH. For example, to
send "Hello World" you just use...
: HELLO ." Hello World" CR ;
Or to identify your RCX, you could use something like...
: WHOAMI ." I am RCX number " RCX_NO @ . CR ;
which in English means...
WHOAMI is a word which
1. Prints "I am RCX number "
2. Fetches (@) the value of RCX_NO
3. Prints (.) it
4. Print s a CR.
Yes, FORTH is a bit archaic in terms of notation and syntax, but that's
because it was designed as an INTERACTIVE language - to be used at a terminal
as well as a compiled language.
For more information and an opportunity to discuss this, please visit Mindfest
later on this year. I'm really looking forward to getting more folks involved.
Cheers,
Ralph Hempel - P.Eng
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Check out pbFORTH for LEGO Mindstorms at:
<http://www.hempeldesigngroup.com/lego/pbFORTH>
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Reply to: rhempel at bmts dot com
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Message is in Reply To:
 | | Re: decoding a message sent by an RCX
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| (...) Yes, you are correct - 11 bits total per byte. And yes, this is very non-standard. I believe the signal is inverted - meaning that IR light is present for "0" bits, and no light for "1" bits. But I'm going from memory here and haven't looked (...) (25 years ago, 4-Sep-99, to lugnet.robotics.rcx.nqc)
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