Ti-83 plus wireless link circuit help

[Halogrunt1234]

There is no programming language i know more than Ti-Basic for the Ti-83 plus, and in looking at the basic layout of the graphic calculator, I was wondering if i could theoretically take a cable, cut it in half, attach radio transmitters and recievers on the cut ends, and have a wireless connection between the calculators.

I know little about radio transmitting and have had no successful experience in making any king of radio link between circuits, but i was juat wondering if i could just use radio as if it were an invisible link and send information through the air. this would definitely be beneficial if i feel like creating my wireless chat program or just making a program and want to send it to another calculator.

i just want to know if somebody can help me by posting a circuit schematic for a 2 way radio link that can transfer any kind of input data (in case there are other type of gadgets that have cable transfer) that I want to add to it.


I also dont want to break FCC regulations and I most DEFINITELY do NOT want any kind of IR link. Is it possible, or am I just being an electronics noob with his head in the sky?

 

[evandude]

you can buy serial RF transcievers. they are designed to do just that... appear as an "invisible link" in a wire. They also aren't very expensive, I think I paid about $10 for the one I got, which is only one-way... or you can get bi-directional ones.

check out sparkfun.com, they have all sorts... in fact right on their main page they have some newer, more advanced ones.

 

[Nigel Goodwin]

Yes, you need to make sure to get ones with encoders/decoders built-in, the ones that are just the radio sections won't work with standard serial data.

 

[DigiTan]

A few years ago, a calc group called Fission Labs come up with a radio link and actually sold a few dozen online until their website went under. The link ran at 433MHz and (allegedly) had a range around 100m. I'm not 100% certain, but I think this level can keep you from having to worry about the RF cops. Unfortuantly, Fission's RF site is no more and sites like ticalc.org got flooded with cheap immitations that either don't work or are poorly documented.

The tough thing about RF calc linking is that the link needs 2 bi-directional channels in order to function (this goes for get( and send ( commands, file transfers, and most 2-player games). Also, the OS runs the link at 9600bps, so your encoder will have to work at that rate or higher. Most 2-player games are synchronous, so they are less of a problem.

So to 2nd what Nigel says, you'll need a special encoder to overcome this problem. But it has been successful in the past. I don't have any schematics on me right now, but I'll check my files and see if I still have a copy of the Fission design. 8)

 

[Halogrunt1234]

I have thought that it was possible, and i only need a range of at most 25-50 meters since it is only a link i want within a room within a mostly unobstructed line of site (although I still dont want IR). So because Im transmitting data, that means that I cant just plop radio transmitters and recievers alone the line? darn. So if I have it right, I have to encode it into a signal that can be transmitted via radio, then the signal is going to be detected by another reciever, then decoded, then it reaches the recipient calculator. then that calculator has to send data through the same jack back into the circuit, encoded, transmitted, recived, decoded, and it goes back to my calculator to be interpreted by my program to output a text message or just simply show that the other person has moved their character. I also think that it is going to have to have its own power supply for simplicity's sake (and also the fact that i am not authorized to open my calculator ) and its going to have to be at a set frequency and stregth to prevent being nabbed by the FCC. I also have to create a program that uses Ti-basic to actually communicate between the calculators. Also it needs to be removable for basic practicality's sake.



This is going to be tough.

 

[JFDuval]

Hello!

Sorry if I'm not directly related to the initial subject, but you seem to be pretty good with TI calculator, and that means you could help me. I own a TI84+SE and I would like to interface it to a robot. Do you know whats the communication protocol? Do you have spec on it? Datasheets? Thanks in advance.

 

[Halogrunt1234]

DigiKey might be able to help you, but i dont know much about Ti 84 and I know less about external control using any of Texas's Instruments.

 

[DigiTan]

The best place to look for link info is probably Joe Clussman's All about the 86 linkport. Don't let the title fool you, most of this information applies to all TI graphing calculators including the newer 83+ and 84+.

Normally, get/send commands are only successful if CBL equipment is involved but I've heard a few reports that those commands are useful in robotics too. Writing an assembly code program will give you the greatest control, but it's very difficult to work with so there's sort of a trade-off.

Somebody pulled off a simple calc-guided robot in the late 90's and I'll post up that link as soon as I can find the info on it again.

 

[JFDuval]

Thanks a lot, it seems to be exactly what I wanted.

 

[Halogrunt1234]

new update on project:
I have created a very primitive program for "over the link" communication between the two calculators. I will say right now that this program is EXTREMELY primitive and may have small logic bugs in it.
The code is as follows:
Program:LNKT

:Lbl 5
:Menu("LNKCOMM","SEND",1,"RECIEVE",2)
:Lbl 2
:ClrHome
rgmLNKR
ause
:Goto 5
:Lbl 1
:Input "MESSAGE?",Str1
:Goto 5

Program:LNKR

:Get(Str1
isp Str1
:Str1->Str2
:While Str1=Str2
:Get(Str1
:end
isp Str1

I can also add a few lines to turn the "Disp" display method into the "output" display message by adding a few more lines of code if i wanted to view messages that are longer than 16 characters, but i like the Log-like feel of Disp and i can change it if i come across a problem.

also i think a logic bug will come up when somebody is "sending" me a message while im trying to create a message, which will both be stored as Str1 and i will possibly lose the message entirely when the other person just happens to want to recieve immediately after. This bug is possibly going to require much more lines of code to fix, and im not going to worry about it just yet.

So now ive got the basic programming down, i just need a wireless link that would be cabable of acting like an invisible cable and being able to send a String variable across the link.

 

[Halogrunt1234]

I just hope that this can work as if the calculator thinks its sending information across a 3 inch cable, but its reallysending across a radio link at a maximum distance of about, say, 20 or 30 meters.

 

[Halogrunt1234]

good and bad news

Good news is that I found a schematic for a radio link for this purpose. bad news was that this shcematic was found on a page that soon went out, and I was only able to get 12 pages in which the schematicas are half cut off.

the site address was

**broken link removed**

sigh...

 

[Nigel Goodwin]

good and bad news

Good news is that I found a schematic for a radio link for this purpose. bad news was that this shcematic was found on a page that soon went out, and I was only able to get 12 pages in which the schematicas are half cut off.

the site address was

**broken link removed**

sigh...

Don't dispair!

I just tried the site, and it's working fine again :lol:

 

[Halogrunt1234]

Im not going to be able to do anything more with the calculator until about september because I have to turn in the calculator back to the classroom.


...


If only there were some kind of online simulator of the Ti-83 plus that I can use to make programs on so it acts exactly like the Ti-83 would. that would be nice.

oh well, farewell, oh 70 programs on my calculator... farewell

 

[DigiTan]

Most game developers and myself use Virtual TI from ticalc.org. It emulates any calculator model as long as you have the right ROM. The trouble is, ROM sharing is illegal, so you need to upload your own calc's ROM image to Virtual TI first. Also, they weren't able to emulate 83+'s flash memory, but is not a problem for basic projects.

Anyway, there is a virtual linking feature that can let your serial, parallel, or USB (maybe) connect to a RF link.

 

[arigold125]

schematics

i found schematics at **broken link removed** I dont know how well this system works and am trying to build it as we speak, but am having difficulty finding all the peices for within the $15-20 suggested price range. anyone who can provide assistance of any kind, it would be greatly appreciated.

 

[arigold125]

anyone know where i can buy the coils required for this project to work or of any other projects or pre-built systems that would give the ti wireless capability?

 

[audioguru]

It is only a VHF transmitter, something like a toy FM transmitter, and a crystal AM VHF radio receiver.
The coils could be just about 10 turns of enamelled wire with a 3mm air-core.

 

[arigold125]

do you think itll work?

 

[DigiTan]

Yeah, audio. Do you think it can work? Or what would you recommend?