Minimal Wide-Range Resistive Sensor-to-Microcontroller Interface for Versatile IoT Nodes

Abstract

Sensor interface is a term including all the circuits adopted for providing measurement readouts from sensor signals. Starting from early 2000s, a plethora of solutions, generally addressed as direct sensor-to-microcontroller interfaces, has been proposed. This concept is particularly intriguing given the widespread adoption of smart devices following the introduction of the Internet of Things (IoT) paradigm. However, the use of those strategies is often limited by the reduced input dynamic range they offer. In this paper, authors propose a novel universal interface for resistive sensors, able to provide an overall measurement range larger than 100 dB, combining consecutive sub-ranges leveraging on volt-amperometric and integral measurement approaches. The procedure for determining sub-ranges is detailed; error analysis for estimating the impact of (active components) nonidealities is furnished as well. Moreover, to evaluate feasibility and obtainable performance, a proof-of-concept prototype has been implemented. In particular, a relative error of 1.31% results for fixed resistor measurements ranging from less than 1 kΩ to more than 100 MΩ. The capability to track slowly-changing measurand (a common scenario in many IoT applications) has been also verified, given a maximum measurement time of about 0.6 s.