Low-Power Direct Resistive Sensor-to-Microcontroller Interfaces

• Published in: IEEE transactions on instrumentation and measurement Vol. 65; no. 1; pp. 222 - 230
• Main Authors: Lopez-Lapena, Oscar, Serrano-Finetti, Ernesto, Casas, Oscar
• Format: Journal Article Publication
• Language: English
• Published: New York IEEE 01.01.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Circuits; Design engineering; Detectors; Electrical resistance measurement; Energy consumption; Energy measurement; Enginyeria de la telecomunicació; Instrumentation; Measurement uncertainty; Microcontroladors; Microcontrollers; microcontrollers (µC); microcontrollers (μC); Ports; powerless sensor nodes; Quantization (signal); radio-frequency identifier; Resistance; resistive sensors; sensor electronic interface; Specifications; Timing devices; Uncertainty; Àrees temàtiques de la UPC; Energy consumption; microcontrollers ( mu \text{C} ); sensor electronic interface; radio-frequency identifier; powerless sensor nodes; resistive sensors
• ISSN: 0018-9456; 1557-9662
• DOI: 10.1109/TIM.2015.2479105

This paper analyzes the energy consumption of direct interface circuits where the data conversion of a resistive sensor is performed by a direct connection to a set of digital ports of a microcontroller (μC). The causes of energy consumption as well as their relation to the measurement specifications in terms of uncertainty are analyzed. This analysis yields a tradeoff between energy consumption and measurement uncertainty, which sets a design procedure focused on achieving the lowest energy consumption for a given uncertainty and a measuring range. Together with this analysis, a novel experimental setup is proposed that allows one to measure the μC's timer quantization uncertainty. An application example is shown where the design procedure is applied. The experimental results fairly fit the theoretical analysis, yielding only 5 μJ to achieve nine effective number of bits (ENOB) in a measuring range from 1 to 1.38 kQ. With the same ENOB, the energy is reduced to 1.9 μJ when the measurement limits are changed to 100 and 138 kQ.