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 Robotics / RCX / 1922
1921  |  1923
Subject: 
Re: frame RCX reply how
Newsgroups: 
lugnet.robotics.rcx
Date: 
Sat, 1 Feb 2003 10:38:30 GMT
Viewed: 
3799 times
  
Hi pat,

take a look at
http://graphics.stanford.edu/%7Ekekoa/rcx/#Protocol

"Pat LaVarre" <ppaatt@aol.com> writes:

Anybody know how to divide the bytes incoming from the RCX IR replies into
correct frames, preferably using javax.comm on a Linux/Windows PC?

I'm told I might want to:

1) Expect first an exact echo of the command packet.

This is what you send reflected by the walls, I think.

2) Expect the reply code to be the op complemented [even bit 3?].
3) Expect the bytes of the reply to arrive one after another, with no
appreciable delay in between [up to how many bytes?].

Bits 0-2 of the opcode tells you the number, with 6 meaning 0
and 7 meaning 1.  For some special opcodes it is longer.

I wonder what the arrival rate actually is.  Could it be:
(8 data + 1 parity + 1 stop bit) /byte / 2400 Hz = 1/240 s/byte = 4.167ms/byte.

+ 1 start bit


I think there's some Java code for this in Lejos,
though I haven't looked myself.


Good luck

Jürgen

--
Jürgen Stuber <stuber@loria.fr>
http://www.loria.fr/~stuber/

I åa ä e ö å i öa ä e å.



Message has 2 Replies:
  Re: frame RCX reply how
 
(...) Ah, thanks. Can we therefore conclude 45.8 ms/byte = 11/2400 s/byte for each byte of a burst? (...) Tell me more? Do we mean to say RCX in the middle of a football field echoes less well? Should I discard the echo, rather than checking it for (...) (21 years ago, 1-Feb-03, to lugnet.robotics.rcx)
  Re: frame RCX reply how
 
(...) Anyone know more specifically where to read how Lejos frames standard RCX IR replies? Does Lejos even include any .java code that runs on the PC? I mean to be asking how a PC should frame the standard replies from Lego RCX fimware, not how a (...) (21 years ago, 1-Feb-03, to lugnet.robotics.rcx.java)

Message is in Reply To:
  frame RCX reply how
 
Anybody know how to divide the bytes incoming from the RCX IR replies into correct frames, preferably using javax.comm on a Linux/Windows PC? I'm told I might want to: 1) Expect first an exact echo of the command packet. 2) Expect the reply code to (...) (21 years ago, 31-Jan-03, to lugnet.robotics.rcx)

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