Re: TI-H: Ein Reich, Ein IR Link

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Re: TI-H: Ein Reich, Ein IR Link

>pea@dalnet.se wrote:
>> Now I also have a success with TI85-irlink! I did it just a while ago! My
>
>Okay, so now we have at least _three_ different IR links that work at least
>partially, and probably there will be more of them in the near future. I'd
>strongly suggest that we make only one or at most two (e.g. for totally
>different purposes) IR link(s). The definitive IR link must meet some
>criteria, so it won't just be thrown away and replaced by another design,
>because we'd soon have a really big mess. We already have quite a few IR
>link designs, most of them which don't work very well, and many newbies ask
>information about "the IR link". I wonder how much money has already been
>wasted on building non-functional IR links?

I care about IR links so I wasn't gonna get into this discussion, but
I guess I'll step in and say a few things :).

>So, instead of competing, I suggest that all IR link builders on this list
>share their ideas and try to concentrate on one, definitive IR link.
>Perhaps we could even have a name for the project (just like Fargo had), so
>it wouldn't be confused with the old projects? Any suggestions?
>
>I don't think I'm going to design any IR links anymore. I had my project
>and I scrapped it, and that's it. But I'm going to give a few suggestions
>for the criteria that the new, joint-forces IR link should meet:

I don't think there should be a collaborative effort on the IR link.
Some people obviously know more than others about what's involved, so
what's the point of having everyone on the same team?  The people who
know less would only drag the others down.  That's just my opinion of
course :).  It only takes one person to come up with an IR link, and
may the best designer win!  From what I've seen that hasn't happened
yet.

>- It _must_ be 100% compatible with _any_ protocol out there, including the TI
>protocol, I2C, the Expander SF protocol, the protocol used by the TI Light
>Flasher etc. The only allowed exception is speed, because it's impossible
>to make an IR link that's as fast as a real link cable. But still, it
>should be as fast as possible. Perhaps a high carrier frequency, like 500
>kHz, would help here?

Standard infared LED's cannot be switched at that rate.  They can
barely be switched at 100khz much less 500khz.  Also to be compatible
with other devices it must be modulated at a standard rate like 40khz
which is what the hp48 and standard Tv/VCR remotes use.

>- It mustn't suffer too easily from interference from the sun, lamps and so
>on. It would also be very good if TV, VCR and other remote controls
>wouldn't interfere with its operation. Again, a high carrier frequency
>might be the key.

The point of modulation is to get rid of possible ambient light
interference... but you can't get rid of stuff from other IR devices.
It will always have some signal interference when you're modulating
past a certain rate, especially with the crude filtering that a cheap
IR link will have.

>- It must have a relatively long range. I don't know what's possible, but
>I'd say ten metres in normal lighting conditions etc. is a minimum.

Well, that ain't gonna happen but oh well :).

>You are, of course, allowed to disagree with me. It's possible that
>somewhere out there someone has already made a link that meets all these
>criteria (and possibly even more?), but I've not yet heard of such a
>project. Mel Tsai is, as far as I know, going to implement an IR link in
>his Expander II/III projects, so he should also be contacted.

I have scrapped the IR link idea simply becaues I no longer see any
point...  Can anyone honestly say that the IR link will be worth the
work?  "Oh boy mommy, look I can send stuff to my friend who's 5 feet
away THROUGH THE AIR!"  It's magic!" :).

I have been through all the possible designs (haven't looked much at
what's been done within the past week by others, but what I've seen
is, umm, well, I think you know what I've seen :).  Not one of the
design's I've come up with will meet these criteria:  cheap, easy to
build, good accuracy, acceptable speed, and small size.

My only real opinion on this is that we should COMPLETELY AVOID
proprietary IR controllers like IR communcation chipsets, unless it's
like an IrDA comm IC.  Just do it with discrete or highly available
electronics.  Trust me :).

>I'm starting to believe that meeting these criteria without having a
>microcontroller involved is just about impossible. 

You have seen the light!  OH YEAH BABY :).

(If I sound cranky it's probably because of my 5 hrs/night sleep
average this past week :).

-Mel
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The TI-Memory Expansion Homepage
-http://www.egr.msu.edu/~tsaimelv/expander.htm
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