Low Cost Smart Sensor Design

Abstract

Problem statement: Sensor with local processing power that enables it to react to local conditions without having to refer back to the central controller. The size and the cost of smart sensor circuit have been reduced. Approach: The use of microcontroller, such as (PIC16C715), with an 8-bit ADC (Analogue to Digital Converter) in one chip. This reduction in the circuit size makes it possible sometimes to incorporate the primary sensor with the signal processing circuit in one unit, then the lookup table should be modified accordingly. The program mobility of smart sensor enables the system to perform self calibration routine by applying known input voltage signal, where its corresponding expected value is stored in the self calibration code. Results: The correction for the measurement signal is done by multiplying the measured signal by the gain correction value and then adding the result of the multiplication to the offset compensation value. The smart sensor performs the self calibration routine for every new measurement value, to adapt any changes in the system environment such as temperature drift. Conclusion: The system performance has been enhanced by implementing the PIC16C715 Circuit design complexity and cost has been reduced and also it’s easy to upgrade.