Subject:
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The pain of communicating with the RCX
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Newsgroups:
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lugnet.robotics.rcx.pbforth
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Date:
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Thu, 9 Mar 2000 18:21:24 GMT
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Viewed:
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1718 times
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The power of Forth lies in the ease with which a system can be built and
and tested both incrementally and interactively. Unfortunately I'm experiencing
severe difficulties estasblishing a reliable communication channel between my
PC (Linux) and the RCX (RIS 1.5). I'm hoping you people can help me (and
others) to annihilate those difficulties, so forth can be used the way it is
intended to, and not in a compile-with-as and download manner.
1) How do you ship forth code as text to the RCX? Downloading an srec file
is no problem, but when I try to do an ascii download, I always get some
communication failure somewhere. I tried increasing line and character
delays up to 200ms and 80ms resp., but although this made the problem less
frequent it did not cure it. When working interactively comm failures occur
too, but retyping a single line is not as annoying as trying to reload an
entire file. Deminishing file size helps a bit, but downloading a single
tiny file for every word is a pain.
2) How can I upload an augmented forth system from the RCX to my PC? I think
rx (=Receive X-Modem; from the lrzsz package) gets confused by the echo of
the IR tower: It reports an `025 received error'. This is a NAK in octal.
Presumably the very NAK rx has sent to initiate the transfer. I found
an old program called xcomm, which fares a little better. It downloads the
entire file, but reports a timeout in the end. When I try
: z S" Hello" ;
z X-SEND
and start the transfer by typing ^U, the header and string is transferred,
then a little pause occurs, and the checksum is sent. I don't see any 0s to
fill the block to 128 bytes. Doing "0 emit" doesn't give me a 0 either. This
explains the timeout error, but not why a 0 isn't transmitted. Does the IR
tower eat them?
I'm suspecting the IR tower of subversive activities (see how guiltily it
blinks with its single green eye!), even more so because information gathered
on the web (in particular Kekoa Proudfoot's page) seems to indicate that it
was designed to handle only a very restrictive query-answer protocol. This
would mean every (few) character(s) should be wrapped in an IR-tower packet
which is subsequently transmitted. This requires of course special software
on both the PC and the forth side, so the simplicity of using just any
terminal emulator is gone:(
Has anybody more information on this, or maybe even (the beginning of) a
solution?
Ernst
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Message has 2 Replies:
 | | RE: The pain of communicating with the RCX
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| (...) Good. I'm glad your on-side so far :-) (...) You are right. I have found that getting a reliable connection is very dependent on ambient light, the voltage of the RCX batteries, and the tower itself. Try to use the tower in NEAR mode so that (...) (25 years ago, 9-Mar-00, to lugnet.robotics.rcx.pbforth)
| | | Re: The pain of communicating with the RCX
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| I might be able to help somewhat. I use my PC running FreeBSD to talk to my RCX (RIS 1.5). After much heartache I found that if I used "ecu" as my terminal, it worked. I tried everything just to try them, and ecu worked the best. Ecu is old, but it (...) (25 years ago, 9-Mar-00, to lugnet.robotics.rcx.pbforth)
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