Understanding Smart Sensors - Nomads.usp

Smart Sensor Basics 7Power supplyPower supplyPower supplyPower supplySensorInterfaceelectronicsMCU / DSPand memoryOutputsignalconditioningOutputdevice(s)Mechanicalactuator ordisplaySoftwareFigure 1.4 Generic control system.and the output device. Smart sensing includes a portion of the controller’sfunctions in the sensor portion of the system. That means software will play anincreasingly important role in smart sensors. The power supply requirementsfor the electronics and the sensor represent an additional consideration that isbecoming more important as MCU voltages are decreased and more sensors areused in battery power or portable applications. The number of supplies inFigure 1.4 may not be required for a particular application, but they serve as areminder for considering the available voltage for the sensor and the interfaceversus the rest of the system.The smart sensor models developed by several sources [5–7] have as manyas six distinct elements for analog sensors. As shown in Figure 1.5, in additionto the sensing element and its associated amplification and signal conditioning,an A/D converter, memory of some type, and logic (control) capability arePower supplySensorelementSignal conditioningand amplificationADCBidirectionalsensor busMCUMemoryControllerFigure 1.5 Smart sensor model.