Requesting a little directional help to emulate commands sent from the TI-84 calculator via the link cable (calculator-to-calculator) using a Raspberry Pi and Python code. Currently the TI-84 basic programs communicate with a Basic Stamp II which drives 2 servos. Commands from TI-84 are merely numeric codes. The objective is to replace the calculator with a Pi. Then write Python code sending and receiving over the GPIO emulating communications with a TI-84, while making no changes to the Basic Stamp II. This is headed toward a STEM related program and any advice will be greatly appreciated.

Silly question: are the servos powered by the Basic Stamp II ? That is, would it be technically possible to simplify the design by replacing both the calculator and the Basic Stamp II by the RPi ? Would it fit the teaching goals and timeline ?


For the record, he wrote a slightly different text on the tilp-users ML several days ago, but his message was discarded by the SF infrastructure. I replied this morning, containing a mention of Cemetech, but he had already found it on his own.

Thanks, Lionel. Since it's possible to speak the TI link protocol using an Arduino, it should absolutely be possible to do the same with a Raspberry Pi and some well-crafted C code. Do you have any experience with C/C++ and interfacing with the GPIO pins on the Pi, awm119?

Thanks Kerm, great site. I'm working thru the forums, esp. Arduino related. I know enough C/C++ to be dangerous, but as you can see below the goal is to work this out with python. Lionel was also kind enough to respond with suggestions which are also being investigated.
The Calculators, and Basic Stamp II robots (with link cable attached) are available, and used for math learning, etc. Simple TIBasic is used to pass codes to the robots. The RPis are also available, and this new project task is teaching python code on the Pi using GPIO. Simply stated, without destroying anything we have, the thought is to wire a 2.5mm jack to the GPIO, and emulate the calculators' communications using the Pi. Ergo, the requested direction.

Awm, I'm afraid that I have been completely AWOL due to some work deadlines, but I'm back now. I did indeed miss the original goal of doing what you can in Python. Have you made any progress figuring out where to start with this based on existing documentation? If there are Python functions to toggle the GPIO lines' statuses, then we should be able to work from there.

Yeah, Kerm, the Raspberry Pi foundation released a GPIO python module.

Here's how you install it (if nescessary):

Code:


Here's a nice reference which covers best practices and reference in various languages including python.

Sorry, been sidetracked also. I've toyed with the GPIO libraries before, turning leds on and off, and handling interrupts. That's the extent of my exposure to RPi's GPIO. So in answer to your question, the libraries can handle lines' statuses. I was able to purchase a 2.5mm stereo female jack (Radio Shack) to use with the link cable. I should be able to connect the BSII and link cable with the jack plugged into the GPIO (via breadboard). Then hopefully it's on to figuring out the software. The TIBasic is simple (a mere send and get). I'm open to all suggestions. Thanks again Kern for following up, and to ElectronicsGeek for the info.

Kerm - Just a heads up - had success with RPi python and TI84+ communications. Reviewing the arduino code you developed was a good start, but my difficulty was locating and using the appropriate handshaking protocols. The GPIO handling is very similar to your arduino code, but in order to emulate the calculator, I needed to capture the conversation between the calculator and the robot pic. Once the handshaking was understood, I was able to complete a send and get from the calculator capturing the entire conversation. I then turned the code around connecting the robot to the RPi and basically replayed the conversation. Your site, ticalc.org, and merthsoft.com, among others, were very helpful. Without them, I would still be clicking and hoping. One interesting note: the TI-84+ identified itself as a TI-82 on the initial message sent. I believe this is a default for perhaps unknown CBL devices. So, I used link protocol documentation for the TI-82. It may be the same as the 84, but ... Thanks again to the contributors to these sites.