Re: TI-H: IR Link


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Re: TI-H: IR Link



KEITH T BURZINSKI wrote:


> >If it doesn't work, I might design a new one.
> COOL!  I'll help...
> 
> >I have no experience in building IR devices and not
> >much experience in electronics either,
> GOOD GOD!  ;)


Good...help is what I need... ;)


> >but I think that with some help from this mailing list it
> >would be possible for me to build a working IR link for
> >two or even more TI calcs (an IR LAN in a classroom
> >would be really great! :) ).
> Okay.  Before we go ANY further, let me say this:
> THERE IS NO WAY TO LINK MORE THAN TWO TI-85s TOGETHER WITHOUT THE USE
> OF A MICROCONTROLLER OR MICROPROCESSOR SOMEWHERE IN THE CIRCUIT.
> (Been there, done that.)  It just isn't possible to do with simple
> logic gates, and the two wires on the TI.  You need more power than
> those devices can provide.  I'm NOT trying to shoot down any ideas,
> just to make a point here.  Got it?  PLEASE DON'T FLAME ME, at least
> not on the lists.


Not exactly. With the built-in TI-85 protocol, it isn't possible, but
you can always use the processor of the TI itself by making your own
software. So it _is_ possible, although quite difficult.


> >It should probably be connected to the link port.
> Good idea!  ;)


Well, you CAN try to link it directly to the processor, but...
(That would make some things easier I think..)


> >The main problem in IR is that you have only one
> >channel (unless you want to experiment with different
> >wavelengths, but I'm not going to do that), so you must
> >somehow modulate the R and W signals in just one channel.
> No, in fact this WOULD be easy.  All you need to do is get two 556
> timers, and hook them up so that they occilate at a HIGH frequency,
> one slightly different than the other.  (You do NOT need to even
> THINK about wavelengths)  Then hook up a detector (GP1U52X -- R.S.
> Cat. No. 276-137; Includes everything you need to know, and
> schematics, which would only need to be modified slightly for our
> purposes) to two 567 Tone Decoders, one to detect each frequency.
> Believe it or not, this can all be done with 2  NE556 Timer Chips and
> 2 567 Tone Decoders (and of course, the IR detector module and a few
> other components).  This circuit IS relatively small, especially when
> on a PC board.
> Hmm... I think I'll try to build a prototype this week.


Oh, I didn't think about that possibility, I thought about light
wavelengths, there are IR transmitters and receivers of different
wavelenghts but using them might be difficult because the wavelenght
probably would overlap a bit and cause interference...that's the way
Mark Levine thought it would work. (No offence, Mark!)


> >Then my questions:
> >Does this sound stupid?
> NEVER!  It is VERY POSSIBLE.  Just don't get in over your head with
> those microcontrollers; keep it cheap and simple, like my idea.


Good. Just thought it might because no one had started a discussion
about it... :) Everyone seems to be more interested about the RT link..


> >Anyone willing to help?
> Of course.  Anytime.  I have quite a bit of experience with IR
> circuits...   :)


That's good, we need an expert here (to blame on when everything goes
wrong. ;) )


> >Is there actually any interest in the idea or is everybody just
> >expecting a working radio link?
> Well, the RTLink is a bit more practical (it goes through walls), but
> IR should be pretty simple.


And IR is 100% legal.


-Ozone


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-- 
*** Osma Suominen *** <a href="mailto:ozone@clinet.fi">ozone@clinet.fi</a> *** http://www.clinet.fi/~ozone
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