ti-0

Overview

ti-0 is a hybrid physical and digital phone module project that turns a TI-84 CE calculator into a simple phone interface by pairing it with a Raspberry Pi Zero and a cellular (SIM) module. The Raspberry Pi handles cellular connectivity, call/SMS routing, and power management; the TI-84 CE provides a minimal user interface on the calculator's screen and keypad.

This repository contains the code, documentation, and assembly notes for both sides of the project (calculator-side code and Pi-side controller scripts).

Features

• Make and receive calls using a SIM-equipped cellular modem attached to a Raspberry Pi Zero.
• Seperate battery, so the module can be a standalone phone through SSH
• Send and receive SMS messages.
• Minimal, calculator-native UI on a TI-84 CE for dialing, call status, and SMS viewing.
• Email client on the TI-84, sends through the pi zero.

Hardware (recommended)

• TI-84 Plus CE (or compatible CE model)
• Raspberry Pi Zero 2w (Raspberry Pi Zero 2wh recommended, as it has presoldered headers)
• Waveshare GSM/GPRS HAT, or applicable sim800c module
• microSD card for the Pi OS (32-64gb)
• Pi zero UPS(A) HAT. (Make sure it connects underneath through pogo pins)
• Ti-Link cable (Mini USB -> Micro USB)
• Antenna for the cellular module (Most hats come with one)
• Throwaway (PrePaid) Sim card. I recommend one with about 5gb of data.

Note: Make sure you do not plug in power for the raspberry pi, while the battery is on, this will fry the Raspberry Pi Zero.

Software stack

• Pi-side: Python 3 scripts (controller, serial handling, AT command interface to modem)
• Pi OS: Debian-based Raspberry Pi OS recommended
• Calculator-side: compact app/program that runs on the TI-84 CE, There is also 2 ASM scripts you need to install on the calulator.

Quick start (Pi)

1. Flash Raspberry Pi OS (Lite is fine) to your microSD card.
2. Boot the Pi and enable SSH/serial as needed.
3. Install system dependencies and Python packages:

sudo apt update && sudo apt install -y python3 python3-pip git
git clone https://github.com/literal-gargoyle/ti-0/
cd ti-0
pip3 install -r requirements.txt

4. Wire the cellular modem and TI-84 CE as described in the hardware notes (calculator/ and docs/ subfolders). Ensure the SIM card is active and the modem has an antenna.

5. Start the Pi controller

python3 source/pi/server.py --device /dev/ttyS0

Modify the device path to match your serial device (for example /dev/ttyUSB0, /dev/ttyAMA0, or a USB-serial adapter path). This can change between calculators.

Quick start (Calculator)

• !!Make sure that your calculator is running OS version 5.4 or earlier. If you have a calculator with the latest, or a version newer than specified, you need to install arTIFICE on your calculator.!!
• Build or copy the calculator-side program to your TI-84 CE using your preferred TI transfer tools (TI-Connect CE, Cervantes, or community toolchains). Typical file formats are .8xp or calculator-archive packages.
• !!Make sure your calulator is fully charged during this process.!!
• Start the program on the calculator and follow on-screen instructions to pair with the Pi (USB or serial). See source/ti-84/README.md for build and install specifics.

Usage examples

• Dial from the TI: enter number, press Dial — the Pi will send AT commands to the modem and forward call status to the calculator.
• Send SMS from the calculator: compose a message and send — Pi relays it via the modem.
• Logs and debugging are available on the Pi (check logs/ or stdout from phone_server.py).

Pi debug run:

python3 source/pi/server.py --device /dev/ttyUSB0 --log-level debug

Adjust --device as necessary

Development

• Keep Pi code modular: separate serial/modem logic from high-level routing.
• Add tests for parsing AT responses and for message/call state machines where possible (unit-testable Python modules).
• If you add native TI code, document the toolchain and provide a small build script in source/ti-84/scripts/.

Troubleshooting

• Serial permissions: add your user to the dialout group or run with sudo for testing.
• SIM module startup: some modules require a stable 4V supply or a capacitor to handle transmit current spikes — consult the module datasheet.
• Check antenna and carrier signal (AT+CSQ to get signal quality).

Security & Legal

• This project directly interacts with cellular networks and user communications. Be mindful of local laws and carrier terms of service when making calls or sending messages.
• Do not expose the Pi controller to the public internet without proper authentication and TLS.

Roadmap / Status

• Status: experimental / proof-of-concept, I'm currently working on making the hardware for this project, I will try to update as frewuently as possible.
• Planned: better UI on the calculator, auto-reconnect on signal loss, battery/power-management improvements, richer SMS threading. Encyption.

Contributing

Contributions welcome. Please open issues for bugs or feature requests and send pull requests for changes.

License

CC BY-NA-SA 4.0

Authors / Contact

• Primary: @literal-gargoyle
• Contact: waltuhwhiteyo1234@gmail.com