Simple Two-Wire Lead Compensation for Resistive Sensors Using Microcontroller ADCs

This article introduces a simplified two-wire measurement system for accurate resistance measurement of resistive sensors, leveraging the Anderson current loop. The proposed configuration features a precision reference resistor ( ${R}_{\text {ref}}$ ) and two diodes ( ${D}_{{1}}$ and ${D}_{{2}}$ ), directly interfaced with the analog-to-digital converter (ADC) and output pins of a microcontroller, eliminating the need for external stabilization resistors. Utilizing ratiometric voltage measurements and an adaptive tuning factor, the system effectively compensates for lead-wire resistance and diode mismatches. A prototype implemented with an ATmega2560 microcontroller demonstrates accurate resistance measurements in the range of 60– $320~\Omega $ , corresponding to a Pt100 sensor, achieving an uncertainty error of less than 0.13% for a lead-wire resistance of $4.87~\Omega $ and 0.15% for $10.0~\Omega $ . Experimental results confirm the system’s precision and reliability over long lead lengths, offering a cost effective and robust solution for industrial and remote sensing applications requiring accurate temperature measurements.