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Subject: 
IR Tower
Newsgroups: 
lugnet.robotics
Date: 
Tue, 22 Dec 1998 19:13:27 GMT
Original-From: 
dave madden <DHM@spamcakePARADIGM.WEBVISION.COM>
Viewed: 
1122 times
  
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?

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
    In:
    Type> 10
    No echo: sent 55 ff 00 10 ef 10 ef
              got 55 ff 00 ef 10 ef 10
    In:
    Type> 10
    No echo: sent 55 ff 00 18 e7 18 e7
              got 55 ff 00 e7 18 e7 18
    In:
    Type> 10
    No echo: sent 55 ff 00 10 ef 10 ef
              got 55 ff 00 ef 10 ef 10

I've added some spaces to make the numbers line up.  As I understand
the IR protocol, it looks like the adapter is working correctly, and
perhaps the tower just swaps bytes around (inverts them?) before
sending them.  I just opened my tower, and there's a pair of 74HC132s,
which are quad 2-input NANDs.  Hmmm, 2 bytes' worth of inputs...a
discrete toggler...yeah, that might work.

Anybody else interested in using a non-Lego(r) IR adapter?  Now that I
think of it, I bet you could use the IR ports that are becoming
standard on laptops, and I think the Palm-III has one too.

d.



Message has 3 Replies:
  Re: IR Tower
 
Dave, I would be curious if anyone has played with the laptop IR as well. It seems like this should be fairly easy to do. I have seen someone doing "something" with the palm IR, although not fully functional. The link is around here somewhere. Have (...) (26 years ago, 22-Dec-98, to lugnet.robotics)
  Re: IR Tower
 
(...) They all have an extremely limited range, however. IrDA is designed to work at distances of < 1m. You can, however, get a high-power IR booster for the palmpilot, so as to use it as an A/V remote control. -Ian (26 years ago, 22-Dec-98, to lugnet.robotics)
  Re: IR Tower
 
(...) 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 (...) (26 years ago, 23-Dec-98, to lugnet.robotics)

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