tailieunhanh - Interfacing PIC Microcontrollers 27

Interfacing PIC Microcontrollers 27. Explore in detail microcontroller interfacing techniques using the popular PIC 16F877 Work through step-by-step examples interactively using circuit simulation software, supplied as assembly source code Gain the knowledge of a wide range of peripheral devices such as keyboards, displays, sensors and drives and serial communication with other processors, memory and more Use interactive simulation software to design and test circuits. | Interfacing PIC Microcontrollers SUMMARY 10 Digital sensors include switches opto-detectors and incremental encoders Analogue sensors produce a variation in voltage current or resistance Their main characteristics are sensitivity range offset accuracy and error Inputs include position speed temperature pressure light strain humidity Sensors are resistive capacitative inductive semi-conductor or voltaic Interface signal conditioning adjusts gain offset and frequency response ASSESSMENT 10 Total 40 1 Describe how the reliability of a mechanical switch can be improved. 3 2 Explain the meaning of interpolation in position measurement. 3 3 Define the term sensitivity as applied to a sensor. 3 4 Explain the difference between the terms accuracy and precision. 3 5 State three sensors for measuring temperature and the materials that each is made from. 3 6 Explain why strain gauges are normally connected as a bridge circuit. 3 7 State the gain required to obtain 50 mV C from an LM35 temperature sensor. 3 8 Sketch a typical linear transfer characteristic and use it to illustrate the effect of varying the gain and offset of the output. 3 9 Explain why the instrumentation amplifier configuration is suitable for interfacing a strain gauge bridge. 3 10 From the LDR characteristic shown state the resistance in kQ of the LDR at lux illumination. 3 11 Describe an analogue and a digital method to measure the angular position of a shaft and suggest an advantage of each type of sensor. 5 12 Describe an analogue and a digital method to measure the angular speed of a shaft and suggest an advantage of each type of sensor. 5 246 Sensor Interfacing ASSIGNMENTS 10 Rain Gauge Design Investigate and design a system for measuring rainfall. The cumulative rain for each day should be displayed continuously. At midnight the total should be logged and the gauge should be reset. Do not design the controller itself but specify its requirements to operate the gauge. Compare alternative .