Subject:
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Re: decoding a message sent by an RCX
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Newsgroups:
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lugnet.robotics
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Date:
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Sat, 4 Sep 1999 00:02:55 GMT
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Original-From:
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Shawn Menninga <smq@dwarfrune.com/saynotospam/>
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Viewed:
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491 times
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At 23:11 03-09-99 GMT, you wrote:
> > 1. The crynwr page states that the serial format is :
> > NRZ, 1 start, 8 data, odd parity, 1 stop bit
> >
> > 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?
>
> You are right - 11 bits. The parity bit is set, so the total number of
> one's is an odd number.
Yep, exactly. LSB first with 0 = carrier and 1 = no carrier at 40kHz.
The following is a transcription of a send of message 156 (9C hex) from
the RCX. (hex 55 ff 00 f7 9C 63 93 6C, three bytes to a line)
0 1 0 1 0 1 0 1 0 1 1 0 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 1 1
,-. ,-. ,-. ,-. ,-. ,-. ,-----------------.
`-' `-' `-' `-' `---' `-------------------' `---'
S 0 1 2 3 4 5 6 7 P S S 0 1 2 3 4 5 6 7 P S S 0 1 2 3 4 5 6 7 P S
0 1 1 1 0 1 1 1 1 0 1 0 0 0 1 1 1 0 0 1 1 1 0 1 1 0 0 0 1 1 0 1 1
,-. ,-. ,-. ,-----. ,---. ,-. ,-----. ,-.
`-----' `-------' `-' `-----' `-----' `---' `---' `---'
S 0 1 2 3 4 5 6 7 P S S 0 1 2 3 4 5 6 7 P S S 0 1 2 3 4 5 6 7 P S
0 1 1 0 0 1 0 0 1 1 1 0 0 0 1 1 0 1 1 0 1 1
,-. ,---. ,---. ,-----. ,-. ,-.
`---' `-' `-----' `---' `---' `----
S 0 1 2 3 4 5 6 7 P S S 0 1 2 3 4 5 6 7 P S
-SMQ Shawn Menninga smq@dwarfrune.com
--=--=--=--=--=--=--=--=--=--=--=--=---=--=--=--=--=--=--=--=--=--=--=--=--
"Well I've wrestled with reality for thirty-five years now, doctor, and I'm
happy to state I've finally won out over it." -- Elwood P. Dowd, Harvey
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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