A discovery from 2007 fully exploited in 2026 - hacking the Casio calculator serial protocol
The Arduino Uno is the board most schools already own for senior classes. Using these as cross-curricula sensor units requires adding a display, a keypad, SD module to save data (the R3 is limited to about 250 readings).
But what if you could build something greater than the sum of the parts? And cheaper?
Greatly extend the capabilities of a calculator many students already own. You can even upcycle old Casio FX-9750 G Plus calculators - and transform both the Arduino and Casio calculator into a general purpose tool for physical education, health, science, mathematics, Internet-of-things (IoT), and robotics / instrumentation. Reduce electronic waste at the same time!
What is that port for again?
The forgotten feature in the 2.5 mm port of a Casio FX-9750 and FX-9860 is now available on my GitHub, open-source and free. It takes the burden off the teacher, because the learners become the experts - constructing, coding and repairing their own smart data logger that also acts as a remote control and automation control interface.
This is an extension of my 2008 research, which carried classroom validation and student feedback, now with a modern facelift and cross-platform compatibility.
Full serial communication between the Casio and Arduino
Full bidirectional communication using the Casio serial protocol works with Arduino, Picaxe, Microbit, ESP8266, and ESP32.
Learners can record heart rate, temperature, sound level, and other readings using sensors they build themselves, for cents or a few dollars.
There low-cost universal serial interface is simple and connects with 5V and 3V microcontroller and Casio models safely.
Instructions, C++ code, teacher and student manual are here:
https://mikefentonnz.github.io/projects/casio-calculator-data-logger-hack.html
So, what do you want to build using a keypad and display most students already have access to at senior level?
- A historical heart rate monitor?
- A NASA Mars orbital surveyor simulator?
- A colorimeter to monitor a chemical change that logs every 2 seconds or every 2 minutes?
- A remote control for a robot?
- A PIN pad to open a secure system?