An open system design using Raspberry Pi: A case study

Abstract

This report describes the development of a physical programmable calculator using a Raspberry Pi as an open alternative to traditional closed calculators. The project addresses the limitations of traditional calculators by creating a modular and extensible alternative. This system allows for both software customization and hardware expansion. The implementation consists of a single board computer (Raspberry Pi 3B), a 4x4 matrix keypad, an I2C LCD, and a custom designed 3D printed case. The calculator is written in the Java programming language using the Pi4J library. This results in a modular design centered around a CalculatorState class that enables easy addition of new operations.

The resulting calculator performs basic arithmetic operations comparable to a simple traditional calculator while additionally offering significant extensibility. Adding new functionality requires minimal code, as demonstrated through the implementation of a square operation which required four simple steps. However, the tradeoffs include higher power consumption and a larger form factor in the use of a Raspberry Pi.

The project validates the feasibility of creating an open source calculator alternative using readily available components. This provides complete user control over both hardware and software while maintaining functionality comparable to traditional calculators.