Subject:
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Re: IR Tower
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 23 Dec 1998 01:30:16 GMT
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Viewed:
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1202 times
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In article <199812221913.LAA23219@paradigm.webvision.com>,
lego-robotics@crynwr.com (dave madden) wrote:
> Hi. I have a Puma IR adapter that I think is fairly generic -- it was
> provided to work with a Sony digital camera, but it receives regular
> IR remote control transmissions, and *almost* works with my RCX.
> However, it appears that the LEGO(r) IR tower does a little more than
> my Puma adapter: talkrcx, send, and firmdl work with the tower, but
> not with the adapter.
>
> Does anybody know what goes on inside the tower before data is spit
> out the serial cable?
Almost nothing. Tx is just the TXD signal gated to send the 38kHz
carrier. It also ties into a timer circuit for the auto-shutoff. Rx is a
little more complicated - a filter/amp/comparator system to detect the
presence of 38kHz IR. I think there's also some sort of AGC on the
pre-amp which is why tranmissions are always balanced (same number of 0's
and 1's).
> Here's a sample of talkrcx sending a ping to the RCX, using the Puma
> adapter:
>
> talkrcx Version 0.2, using /dev/cua1 for the serial port.
> Type> 10
> No echo: sent 55 ff 00 18 e7 18 e7
> got 55 ff 00 e7 18 e7 18
I think the pings look fine. Packets look like this...
55 ff 00 <d0> ~<d0> <d1> ~<d1> ... <dn> ~<dn> <sn> ~sn>
where <d0>, <d1>...<dn> is the message, and <sn> is the simple sum of <d0>
through <dn>.
Responses from the RCX use the ones complement of the command - e.g. if
you send command 0x10, then the response to this has <d0> = ~0x10 = 0xef.
Since I'm not familiar with talkrcx, I may be mis-reading your output.
If you want help debugging this, download nqcc from
http://www.enteract.com/~dbaum/lego/nqc/index.html. If you use the -v
option, then downloading will use verbose mode which logs all I/O to the
console. Capture the output and e-mail me - I can probably figure out
what's going wrong.
Dave
--
reply to: dbaum at enteract dot com
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Message has 2 Replies:
 | | Re: IR Tower
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| In article <dbaum-2212981930170...ract.com>, Dave Baum <lugnet.robotics@lugnet.com> writes (...) I have come across this statement (balanced 0's and 1's) several times but it is not quite true. It would be true if the RS232 frame was 8 data and no (...) (26 years ago, 23-Dec-98, to lugnet.robotics)
| | | Re: IR Tower
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| =>From: Paul Haas <paulh@hamjudo.com> =>... =>The RCX doesn't echo, the IR tower is seeing it's own signal reflected off =>the walls. It's either seeing its own signal, or Tx is looped back to Rx, or something. My generic IR adapter doesn't do that (...) (26 years ago, 23-Dec-98, to lugnet.robotics)
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Message is in Reply To:
| | IR Tower
|
| Hi. I have a Puma IR adapter that I think is fairly generic -- it was provided to work with a Sony digital camera, but it receives regular IR remote control transmissions, and *almost* works with my RCX. However, it appears that the LEGO(r) IR tower (...) (26 years ago, 22-Dec-98, to lugnet.robotics)
|
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