Low-cost interfaces for sensors and sensor systems

This paper discusses the basic ideas, circuitry and applications of a novel family of low-cost transducer interfaces. These interfaces, which are directly read-out by a microcontroller, service the following sensor elements: Pt resistors, thermistors, potentiometers resistors, capacitors, resistive bridges and voltage- and current sources. It is shown that, even when using low-cost CMOS technology, these interface and sensor systems can have a rather high accuracy. The interfaces have been designed for applications where the sensors signals have a low to moderate bandwidth. The main test results for some typical applications are reported in this paper. The accuracy amounts to 1 to 15 bits for a measurement time of 1ms to 100ms. The number of external components has been kept to a minimum.