Infrared Led Link Cables

[DigiTan]

The TV Code-learner/IR link project has hit an unexpected snag. So far, I've been using a Radio Shack IR detector to receiver IR signals. It's been working pretty good until recently. I think it might have something to do with a pair of decoupling capacitors I have between the timing crystal and the ground plane (probably using the wrong value). Recently, I ran low on capactors, so I've been using a different type. I'll try buying more of the usual type today.

Anyway--if it works--the whole thing will be ~slightly smaller than those remotes they use for car alarms. This *might* be small enough to fit inside the original casing--just behind the LCD. (No promises yet)

[edit] Found the problem. The microcontroller was introducing too much noise to the IR detector.

[Keith Pierce]

I need some information on a idea i got. Maybe the idea was already brought up or even made but is it possible to make the infra-red links connect directly to the link port.

Another thing is how do i go along on making my calc (83+/SE) have a light?

[NextPerception]

[DigiTan]

[Keith Pierce]

Thanks guys that helped alot.

[Awesome1]

These wireless links are very interesting to me. I would like to make one but i have no experience in electronics nor are very good at soldering. If you were to finish the design, how much would u charge to have one made for someone including a few programs that could be used with it like wireless chat and wireless games?

[NextPerception]

I wonder if you could make a small thing that could somehow use the am radio waves the calculator puts out for very short range linkless comunications between calculators. (if you don't know what I am talking about hold your calculator next to a am radiop on a empty am station then do something on the calculator outside any asm programs and you get different sounds by doing different processes.)

[X1011]

I can hardly even hear that, maybe it's my radio, but I don't think they're much use.

[DigiTan]

It's possible but it would be very, very, very hard. Almost Sci-Fi hard. There's a (mostly fictional) technique called Van Eck hacking that could be used to reconstruct the processor signals. It's tough because you have thousands of other signals mixed in, and you have to collect and isolate this radiation in a super-precise manner. There are rumors that the NSA has a working Van Eck system, but there's no public proof of it.

Anyway, there are some cool RF-based microchips out on the market now that are small enough to fit inside the calculator without any external parts.

[Adm.Wiggin]

I can't help but laugh when I see the NSA website I find it very humorous that they think they "make" and "break" all the codes.

[DarkerLine]

Some codes really can't be broken. Without the key.

[Adm.Wiggin]

And then there is hashing (like md5 )

[Raster]

Well with the TI wireless link couldnt we use ultrasound? We could use a MC14457 ultrasonic/IR transmitter and the MC14458 ultrasonic/IR receiver. and if we cant It does IR also.

I have no site for info about it, but its still around and I can scan in some docs about it. from a mag. Oh and its a CMOS chip just for a little info.

[DigiTan]

Ultrasound might work. (Some of the earliest TV remotes in the 70's used to use ultrasound. There are still a few problem though, becuase of basic acoustic interferences (echos, ghosting, cancellation, and old fashion noise). Many engineers would conclude that sound is probably to worst medium for data. Audible tones would be even worse, but ultrasound is still a possibility.

[NextPerception]

wow thats a unique idea. Me thinks that may have some problems and besides, the ultra sound stuff is expensive and complex. (and I smell digital electronics me no likes to make digital things, me like the analog)

what if we wan't to use it in space though?
sorry corny joke couldn't help myself though...

[Raster]

Well ultrasound is analog but most of us are probably going to be in school where the teachers are like SHUT THE F@CK UP so itll be quiet and you can chat from a pritty good distance if your in the same room.

[Raster]

Actually let me experiment with ultrasound (if I have the stuff or radio shack, stupid radio shack probably doesnt even have an ultrasonic transducer )

[wrigley]

Ultrasound might not be the best idea. I have an ultrasound controlled stereo. The remote works perfectly, but if you drop a set of keys on the table, the stereo just might start playing song number 5 on disc 3, or turn up/down the volume.

So ultrasound could *easily* work to send/receive messages, the trouble is sending a message could be done by virtually anything with no control over what is being sent (eg the situation with the keys).

[NextPerception]

well if what your saying is true and keys dropping on the floor can cause it to do something I have an IDEA!!! (we need idea~lightbulb smiley face for right here)
have a link activation code. in a format perhaps something like this.

-recieving-calc-id=calc u want to send to
-breaker signal
-1234=represents a series of sound telling the reciever to listen and transmit if all the following data is correctly sent
-breaker signal
-28020.29000 =frequency of the transmision in Hz (min hz.max hz)
-breaker signal
-20 =increments of used frequencys (in this case the used frequencies would be 28030,
28050, 28070, and 28090)
-breaker signal
-720 =length of transmision in bytes
-breaker signal
-wait for one of three responses (if repeat signal is heard then repeat /if continue signal is heard, continue/ if no signal is heard repeat for how ever many times is set in the options then stop trying and report failed transmission to the user)
-assuming continue is heard then send data now
-ask other calc if repeat is required if ans=yes continue else repeat
-end transmission signal
so the final data transmission activation code would be (note-breaker signals will be represented by a "." (no quotes))
recieving-calc-id.1234.28020.29000.20.720

this can probably be refined a little bit but I have decided to name this the DTAC (data transmission activation code) version 0.1
I named it because I can.

[michael816]

Hey I saw this topic and decided to register, so I can post and help/get help from you guys. So this IP Link thing... has anyone done it yet? I have bought a emitter/detector from radio shack and (stupidly) thought I could just cut open a link cable and connect the wires... well I learned its more complacated than that. So if anyone has done it yet... PLEASE show us some pictures of the finished product and a nice procedure on how to do it. Thanks in advance, Michael816.

PS: This ultra sound thing doesnt "sound" very good because, from what I've heard, any slight sound could mess it up... but thats just my opion, i could be wrong.