Understanding Smart Sensors - Nomads.usp

The Next Phase of Sensing Systems 323BulkmicromachineddiaphragmFigure 14.5 Photomicrograph of microcontroller with an integrated pressure sensor. (Courtesyof Motorola, Inc.)capability could be another step in the continuous integration of silicon andelectronic/electromechanical systems.The proof of concept vehicle was built using a 100-kPa pressure sensorintegrated onto a standard 8-bit 68HC05 MCU core along with the associatedanalog circuitry [18]. Figure 14.6 illustrates the block diagram, including an8-bit MCU core (68HC05) with 2K bytes EPROM, 128 bytes RAM, bootROM, and an SPI. Analog circuitry for signal conditioning, a voltage and currentregulator, and a 10-bit ADC and 8-bit DAC were added to the basic core.A temperature sensor was also incorporated into the design for compensationpurposes.14.4.7 Wireless Sensing in the Networked VehicleRF technology can add another dimension to smart sensors. A vehicle providessome interesting possibilities. It is possible to envision small micromachinedstructures with an integrated RF output or input interfaced through an RF busto a remote control unit performing their function without any visible means toverify their presence except the added functionality that they provide to thehost vehicle. That technique is already used in electronic identification in theRFID tag (see Chapter 8). One possible vehicle application is a wireless versionof an electronic “nose” [18]. The device could be mounted in an existing automotivecomponent such as the dome light housing. The dome light housingprovides a central position in the car for the nose to function, similar to a home