Subject:
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IR header how optional
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Sun, 2 Feb 2003 13:56:41 GMT
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Viewed:
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4044 times
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> > in... Kekoa's firmdl3.tar.gz ... the four byte
> > packet x 10 FE 10 FE, equal to the seven byte packet
> > x 55 FF 00 10 FE 10 FE with the header deleted
>
> I haven't seen anything in the docs to indicate
> that the RCX should make some reply to that
> sequence.
Yep. But via our solid new reply framing code, thanks again, now I can see ...
> I would expect that raw byte sequence to be ignored
> by the RCX
Nope. At least not here: now that I look, I see my RCX often doesn't require
the PC to send x 55:FF:00.
IR command packets like x 10:FE 10:FE PBAliveOrNot and x 06:F9 01:FE 0A:F5
34:CB PlayTone work fine without headers, provided I toggle the op & sum with
mask x08 and/or precede a repeated command with PBAliveOrNot.
I wonder what purpose does the x 55:FF:00 header ever serve. I see the web
speaks of warming up IR electronics. I wonder if that's all this does, and if
we're warming up sender electronics or receiver electronics or both.
Anyone know when can we get away with omitting the header?
Maybe any time we answer with another command within a millisecond or so of the
RCX reply?
Curiously, cluelessly, thankfully yours, Pat LaVarre
P.S.
Omitting the header saves 137ms per packet, if I'm correct to apply here such
formulae as:
138 ms/packet = 3 bytes * 46 ms/byte
46 ms/byte = 45.8 ms/byte = 11 bits/byte / 2400 bits/s
11 bits = 1 start + 8 data + 1 parity + 1 stop bit
I mention both 45 and 46 ms/byte because to date searching this group for 45 ms
and for 46 ms finds no quote of ms/byte.
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Message has 3 Replies:
 | | Re: IR header how optional
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| (...) I doubt anything (short of a 2MV Lightning Flash) will warm anything in 1 msec. ;) Also, the receiver won't warm up until the header has been read in completion and decoded. So I doubt it's used for that. Normally, in any communication, you'd (...) (22 years ago, 2-Feb-03, to lugnet.robotics.rcx)
| | | Re: IR header how optional
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| (...) see ... (...) require (...) That's very interesting. And, I've managed to get replies to "headerless" packets as you describe, however... (...) with (...) I still don't see any response to 0x10 0xFE 0x10 0xFE. The even bytes (0xFE) are not the (...) (22 years ago, 2-Feb-03, to lugnet.robotics.rcx)
| | | Re: IR header how optional
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| (...) Whether serial transmission is as simple as start:data:parity:stop repeated, or not, I still have no idea. But I'm posting again to say in those calculations I was off a whole order of magnitude, sorry. I imagine the calculator I used reported (...) (22 years ago, 2-Feb-03, to lugnet.robotics.rcx)
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