Hello everybody !

First of all I am from Germany and so my English is not really good. But I hope I can understand you and the other way round.

Now my question:

I had an idea to connect the TI-84 plus with an Arduino. But it is not so easy as I thought at first.
I have saw this topic:
http://www.cemetech.net/forum/viewtopic.php?t=4771&start=0

Itself it is really nice but my problem is that I do not work with Assembler and only with C/C++ as I program the Arduino often.
I want to build a connection through the Link port or however it named, the one on the left site up. ( I/O).

So is there a chance to build a connection with my arduino, that my Arduino can receive Data which I send form my calculator and also that my calculator can receive one ?!

For the first I only want to send numbers, later words will be very awesome !

First I have build the connection with Software Serial but there is the Problem that the TI 84 works with 3,3V ?!?!??!

I am not sure if I had tell enough about my "project".
I would rejoice at an answer and help !

best regard
Lorenz

Sorry but my english is not good. But I hope you can understand all, if not than ask !


Is this a program for the TI-84 which send a number through the link port: (it is one of my first programs that I wrote, so i am not sure if this works):

Prompt A
Send(A

Welcome to Cemetech, lgrube96! Feel free to Introduce Yourself when you get a chance. To answer your several questions:
- The calculator could be made to work with 3.3V if you used a level shifter. The link (I/O) port uses 5V (TTL) communication
- The link port is not capable of the differential signalling used for serial (RS232).
- The two-line program that you wrote at the end there would work to send A over the link port. Your Arduino-side linking code would have to catch and handle that.
- The code I posted in the topic to which you linked, plus Send( and Get(, are really all you need to make this work.

Ok. But I have measure between GND and one other connection pin of the Cable which comes from the calculator 3,278 V.
I do not know why !?
You've made my day !
You're code is really awesome, thank you so much !
Anyway I have ignore the code. I dont know why...whatever!

Well. One Problem I have.
I can send letters or numbers to my TI84 but I can't revieve one with my arduino or rather I do not know how to do that so far.

Therefore I want to write some words on my TI and want to send them to the arduino. But this is my problem.

I hope you can help me one more time


Thank you so much !

best regards
Lorenz

The link port uses open collector outputs so the high voltage level is dependent on the pull-up resistor inside the calculator (and, in turn, on the condition of the calculator's batteries) - your electrical interface should bear this in mind.

Well...until yet I only use 1 kohm resistor between the two digital Pins from the Arduino and the two "pins" from the calculator, because there was a picture which is shown in the link I post at first.
So I think the connection is ok.

But I have still the same problem with the communication form the calculator to the Arduino.
I hope someone can help me !

You don't need the resistors in this instance, because you're dealing with signalling-level current (ie, negligible). What problem are you having, exactly? Still that you can send numbers/variables from the Arduino to the calculator but not the other way around? What system (eg, which packet type) are you using to send numbers/variables to the calculator? Which one are you trying to use to send data back to the Arduino, and in what way is it failing?

Ok. Now I have connect the calc directly with the arduino.
So. But the Problem is the same.

Until yet I only can send letters or numbers to the calc.
I have this array which I send to my TI:
0x23,0x87,here the number of the letter for example: 0xA1 ,0x00

At the moment I work on a method to send hole words to the calc, but I have some problems because the letters do not send in the right order...

But a big problem is to recieve letters with the arduino. I have no idea how to realice this. However you have to use par_get ?!?!
And on the calc the program:
Prompt A
Send(A

Have you made any further progress with this? You'll probably want to use silent linking to send strings, by the way.

That is the "problem". Until yet I never work with the TI 84 or other calculators and there interface.
So I hoped I can get help in this forum !




So I do had no idea what that mean and what I have to do.

So, strings in TI-BASIC are similar to strings in other languages. To send a string from your Arduino to your calculator, you'll have to use the silent linking capabilities. If you have TI Link Protocol and File Format Guide, you can check out Link Protocol -> Silent Variable Transfers -> Sending a Variable (and Requesting a Variable). A string is formatted as two bytes of little-endian size, then the contents.