교육용 회로 실험을 위한 마이크로비트 ADC의 선형 유효 구간 규명 및 자립적 전압 계측 전략 탐구

초록

This study investigates the reliability of the micro:bit’s embedded analog-to-digital converter (ADC) in educational circuit experiments and explores strategies to overcome its inherent limitations. While the short-term measurement variation is strictly controlled within 1 LSB, the overall uncertainty is found to be dominated by hardware-inherent device-to-device variability, specifically offset and gain errors. To mitigate these deviations, the theoretical voltage division linearity of a precision resistor ladder circuit is established as a conventional true value to evaluate step size uniformity. The empirical results demonstrate that excellent linearity, with a maximum relative deviation of less than 1% from the mean step size, was maintained across a broad range spanning approximately 3% to 91% of the full scale. Based on these findings, this study proposes a practical measurement strategy: selectively acquiring data within this linear effective range, or focusing the analysis on voltage differences (steps) rather than absolute values. This methodology establishes a valid framework for achieving reliable relative voltage measurements in classroom settings without reliance on post-calibration with external standard instruments.

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