DigiCal: Design and Implementation of a Smart Business Calculator for Offline Financial Inclusion of MSMEs
Keywords:
Digital financial inclusion, Embedded systems, GST automation, MSME, Offline POS, Raspberry Pi Zero 2W, Smart calculatorAbstract
Modern smartphone-based Point-of-Sale (POS) systems and digital accounting applications have significantly improved financial transaction management in urban commercial sectors. However, many rural and small-scale MSMEs continue to face challenges due to expensive hardware, unstable internet connectivity, limited digital literacy, and a lack of accessible accounting solutions. Traditional calculators remain affordable and easy to use, but they lack transaction logging, GST computation, analytics, customer due management, or secure record storage. To address these limitations, DigiCal was developed as a smart embedded business calculator specifically designed for offline financial inclusion and digital transformation of MSMEs. The proposed system combines the familiarity of a conventional calculator with advanced business functionalities, including automated GST calculation, transaction storage, customer due management, expense tracking, sales analytics, and financial reporting. DigiCal follows an offline-first architecture, using a lightweight SQLite database for secure local storage, while also supporting optional cloud synchronization and web-based analytics when network connectivity becomes available. The hardware implementation is based on a Raspberry Pi Zero 2W integrated with a custom 5×7 matrix keypad, TFT display, rechargeable battery system, speaker feedback module, and lightweight Python software architecture. Experimental evaluation demonstrated reliable real-time transaction processing, stable offline operation, accurate GST computation across multiple tax slabs, responsive user interaction, and efficient local data management. The system also exhibited low power consumption and dependable transaction storage under practical operating conditions. By combining affordability, portability, and ease of use, DigiCal provides a practical alternative to expensive POS systems while preserving the simplicity of traditional calculators. The proposed platform can support improved financial record management, operational efficiency, and sustainable business digitization, thereby contributing to greater financial inclusion for MSMEs operating in low-connectivity environments.
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