Understanding Smart Sensors - Nomads.usp

Smart Sensor Basics 15Figure 1.10 Two-chip smart sensor for pressure measurements. (Courtesy of Motorola, Inc.)V RL = 0.3 to V RH = 4.7V, utilizing the highest output capability of the integratedsensor.The liquid crystal display (LCD) is driven directly from the MCU byusing the MCU to generate a square wave signal every 32 ms. The backplane isalternately inverted with the segments and out-of-phase with the segment thatis on. Each MCU port is connected to a digit, and two additional input-output(I/O) lines are used to generate the decimal point and the backplane signal.That approach utilizes software to eliminate the need for an additional displaydriver and achieves a reduction in both component count and space. The memoryrequired by the MCU is minimal, only 1 KB read only memory (ROM)and 4 bytes EEPROM, leaving essentially all the remaining memory for otherfunctions. The program for the MCU is written in C, a high-level language.1.5 SummaryToday, it is possible to build a smart sensor for several measurements with basicallytwo semiconductor components: the sensor and the MCU. That is thecurrent phase of development and one of the necessary steps to the next level.The smart money is being placed on areas that take advantage of the number oftechnologies that are available or in developments that will fundamentally