Opencalc pcb V5

Prototype sponsored by PCBWay.

OpenCalc is an open-source graphing calculator inspired by the TI-84, built around an ESP32-S3, a color LCD, USB-C, Python-style scripting, games, and expandable firmware.

OpenCalc-authored software is licensed under GPL-3.0-or-later. Bundled components retain their original licenses; see Third-Party Notices.

The calculator runs OpenCalc OS, the project’s open-source ESP32-S3 operating environment. OpenCalc OS includes the calculator interface, math and graphing engines, built-in apps, scripting runtime, USB file storage, keypad handling, display drivers, game support, and power management.

Website: https://corypearl.github.io/opencalc/product-website/

Blog: https://corypearl.github.io/opencalc/blog.html

Click an image to enlarge. The UI tour visits all 12 apps and the game menu.

Highlights

• A real graphing calculator: textbook-style input, exact and numerical math, complex numbers, calculus, history, typed persistent variables, and unit-aware expressions such as 8 m / 2 s.
• Integrated CAS and graphing: Giac/KhiCAS symbolic math linked to Cartesian, parametric, polar, and sequence graphs, tables, roots, derivatives, tangents, integrals, and points of interest. Alpha + Graph opens exact symbolic analysis for the selected graph, including its derivative, integral, roots, asymptotes, tangent line, and integral shading. CAS results have selectable solution branches, exact/decimal views, domain controls, assumptions, and a searchable command catalog. All graph modes support per-series colors/styles, mode-aware trace and tables, scalable image backgrounds, and direct or recurrent sequences.
• A complete math toolkit: Statistics, Lists, Matrices, Solver, Finance, Conics, Inequalities, and a searchable science and engineering reference.
• Reference Center: press Alpha + Zoom for an interactive periodic table and browsable math, physics, and engineering formulas and explanations.
• Programmable on the device: edit, run, upload, and debug Tiny Python programs with math, statistics, exceptions, local modules, cancellable forever loops, CAS access, graphics, storage, audio, and protected CircuitPython-style sensor objects.
• Built for science and electronics: use Tiny Python, 12 bidirectional digital pins, four 16-bit analog inputs, and shared I2C to control experiments, plot live sensor data, and analyze recordings in Stats.
• Games included: press Alpha + 2nd for Tetris, Doom, Snake, Breakout, and NES/Mario support with persistent high scores, multi-key controls, and optional audio.
• Open hardware: ESP32-S3, 320x240 color display, diode-isolated keypad, rechargeable battery, USB-C, expandable storage, and a documented V5 PCB.
• One-cable workflow: the same USB-C connection handles charging, firmware flashing, serial monitoring, and file storage.
• Dual-core OpenCalc OS: one core keeps the interface and graphics responsive while the other handles background math and system work, with persistent worksheets, configurable performance, and power-saving controls.

Rough production Cost Estimate

Project Layout

firmware/   OpenCalc OS source for the ESP32-S3 calculator
hardware/   key layouts, graphics, PCB files, case files, and hardware docs
docs/       notes and project website files

Quick Start

Install and activate ESP-IDF first; see Espressif's ESP32-S3 Get Started guide. Then connect OpenCalc with a data-capable USB-C cable and build the firmware:

cd firmware
idf.py build

Find the serial port created by OpenCalc:

Look for a new USB serial device after connecting the calculator. Typical names are /dev/cu.usbmodemopencalc1 on macOS, /dev/ttyACM0 on Linux, or COM5 on Windows. Replace PORT below with that complete name; do not type the word PORT literally.

If automatic flashing does not enter the bootloader, hold Boot, tap Reset, and then release Boot. Flash using the detected port:

idf.py -p PORT flash

After OpenCalc restarts, find the port again because its name can change between bootloader and normal operation. Start the serial monitor with the runtime port:

idf.py -p PORT monitor

Press Ctrl+] to exit the monitor. The same USB-C cable supports flashing, serial monitoring, storage, and charging.

Documentation

• Complete OpenCalc OS Guide: in-depth controls, app workflows, games, scripting, settings, build instructions, validation, and troubleshooting.
• Tiny Python Start Guide: create, run, and debug scripts; use imports, math, files, graphics, audio, keys, and scientific I/O.
• Firmware README: build settings, flashing, storage image, controls, apps, games, and firmware status.
• App Status: implementation status for every OpenCalc OS app and game.
• PCB README: current V5 PCB parts, pin map, power path, display, keypad, battery, audio, and bring-up checks.
• Tiny Python README: scripting runtime details.
• Tiny Python capability audit: supported Python and hardware APIs, limits, and the CircuitPython compatibility boundary.

Current Status

OpenCalc OS is a capable working prototype. Every built-in app has its main workflow in place, and the calculator, graphing, CAS, scripting, USB storage, power controls, and all five games are usable. The remaining work is mostly deeper edge-case handling, long-session reliability, and validation of the new V5-only hardware features.

These percentages are practical estimates, not test-coverage measurements. The biggest jobs left are closing Tiny Python's compatibility gaps, handling very large CAS results and unusual math edge cases, stress-testing large matrices and long sessions, and validating V5 audio and scientific I/O on real hardware. See the app-by-app status for more detail.

Credits

• OpenCalc OS, hardware, and enclosure design: Cory Pearl.
• CAS engines: Giac/Xcas by Bernard Parisse and contributors, with the KhiCAS ESP32 port lineage under GPL-3.0-or-later; Eigenmath remains as a BSD-2-Clause fallback.
• Doom engine: id Software's GPL Doom source, Simon Howard's Chocolate Doom work, and doomgeneric by ozkl, under GPL-2.0-or-later notices.
• NES emulation: Anemoia-ESP32 by Shim06 and contributors, under GPLv3.
• Platform: Espressif ESP-IDF, TinyUSB, and the ESP LCD ILI9341/ST7789 panel drivers under their respective licenses.
• Prototype project funding was provided in part by PCBWay.

Complete copyright, license, and game-data details are recorded in THIRD_PARTY_NOTICES.md. Doom WADs and NES ROMs are separate game data and are not licensed under the OpenCalc firmware license.