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 Robotics / RCX / legOS / 529
528  |  530
Subject: 
Even more networking stuff
Newsgroups: 
lugnet.robotics.rcx.legos
Date: 
Sun, 28 Nov 1999 04:03:04 GMT
Viewed: 
1076 times
  
OK,

So I finally got LNP to do something :) I have a very simple program on one rcx
which sends out something to another rcx which the second rcx gets in. Its a
good first step :)

However being the difficult people we are we would like to be able to interface
a PC to our RCX's. Currently we have a PC running a Java application which can
ping and receive a reply from a RCX which is running standard firmware. The
reply program on the RCX was written in NQC and the Java application borrowed
code from a Sun project to control some tanks using palm pilots. Basically the
sun code gave us the packet format necessary to sucessfully communicate with an
RCX from any application (for format of packets see
(developer.java.sun.com/developer/technicalArticles/ConsumerProducts/JavaTanks/Javatanks.html)

anyhow we now want to convert this to a java application talking Lego Network
Protocol. To do this we need more info on the workings of LNP. We have had a
look through the code (lnp.c) and (config.h from the boot directory) and come
to the following conclusions. PLEASE ADVISE where these are right and wrong. If
we get a decent Java app doing stuff on LNP we will release the code next
weekish.

OK general ideas at the moment.

Integrity Layer Packet format :
_____________________________________
|  f0   | length | data *n | chksum |
_____________________________________

Addressing Layer Packer format :
_______________________________________________________________________________
|  f1   | length | dest | host addr ored with port | integlayer packet | chksum
_______________________________________________________________________________

Now the other information that I think that I have gleaned is that the "out of
the box" legOS sets each RCX to have the same host addr (00) I THINK that this
is configured in the config.h file under CONF_LNP_HOSTADDR, is this the case
and if so are we going to have to change this for the firmware in each RCX.
That is do we want to change CONF_LNP_ADDR to 1, 2 , 3 etc for each of the
RCX's that we want on the network and have each running effectively its own
(slightly modified) version of firmware??

Again any help appreciated.

thanks
michael



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