Subject:
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Re: frame RCX reply how
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Sat, 1 Feb 2003 18:31:04 GMT
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Viewed:
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3836 times
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> > Anybody know more? If noone does, then I'll have
> > to decipher code on the web that purportedly
> > works, such as:
> > http://graphics.stanford.edu/~kekoa/rcx/tools.html#Firmdl
I reached:
http://graphics.stanford.edu/~kekoa/rcx/firmdl3.tar.gz
71,680 bytes
Accordingly I'd now guess the firmdl3/rcx_comm.c algorithm for framing standard
RCX replies is:
> rcx_send
1) Send the bytes of the command packet.
2) Loop to receive up to equally many bytes echoed. If 100ms elapses twice
without receiving any bytes, then receive and toss bytes til 200ms elapses
twice without bytes or 4096 are received. Don't worry if the first bytes
received were actually received before step (1).
> rcx_recv
3) Loop to receive the reply up to the expected length. Quit early if the
specified 50ms or 150ms timeout elapses twice without receiving any bytes.
> rcx_wakeup_tower
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?]
> ...
How inaccurate are my guesses? Personally I'm vastly ignorant of the details
of the Linux serial API, but I knew a select in a past life.
Curiously, cluelessly, thankfully yours, Pat LaVarre
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Message has 1 Reply:
 | | Re: frame RCX reply how
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| (...) can be (...) 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: (...) (21 years ago, 1-Feb-03, to lugnet.robotics.rcx)
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Message is in Reply To:
| | frame RCX reply how
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| 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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