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 Robotics / RCX / 1927
1926  |  1928
Subject: 
Re: frame RCX reply how
Newsgroups: 
lugnet.robotics.rcx
Date: 
Sat, 1 Feb 2003 18:51:55 GMT
Viewed: 
3932 times
  
"Pat LaVarre" <ppaatt@aol.com> wrote:

4) Before using (1) .. (3), begin by confirming the packet x 10 FE 10 FE • can be
sent and echoed.  [Perhaps this packet rarely disturbs a standard RCX?]

This is the PBAliveOrNot (or ping) packet type.  It has the side-
effect of reinitializing the toggle bit used to determine repeat packets.

Do you have the Minsdstorms SDK?  It covers all the standard
LEGO packet types in detail:

http://mindstorms.lego.com/sdk2point5/default.asp

Using the SDK might be a better approach than analyzing code
that may or may not conform to the packet protocol.

Mark



Message has 2 Replies:
  Re: frame RCX reply how
 
(...) Ouch, we may be framing the hex differently here, sorry. The only x10 Ping known to me is the x10/18 command op that gets embedded inside of a packet like x 55 FF 00 10 EF 10 EF to provoke a reply packet like x 55 FF 00 18 E7 18 E7, or vice (...) (21 years ago, 1-Feb-03, to lugnet.robotics.rcx)
  Re: frame RCX reply how
 
Concerning the parsing of LEGO packets, I've found these bits to be useful in coming up with a parsing algorithm: * Packets start with 0x55 * Individual bytes of a packet are sent with little or no delay in between bytes * Packets may or may not (...) (21 years ago, 1-Feb-03, to lugnet.robotics.rcx)

Message is in Reply To:
  Re: frame RCX reply how
 
(...) (URL) bytes Accordingly I'd now guess the firmdl3/rcx_comm.c algorithm for framing standard RCX replies is: (...) 1) Send the bytes of the command packet. 2) Loop to receive up to equally many bytes echoed. If 100ms elapses twice without (...) (21 years ago, 1-Feb-03, to lugnet.robotics.rcx)

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