EE 476: Laboratory 5

Capacitance measurement


You will build a system for measuring the value of a capacitor. The value will be read on a four-digit, seven-segment LCD display.


There are at least two different ways you could design a circuit/software to measure a capacitance:

Once you have the capacitance value, you will need to Display the capacitance on LCDs using a icm7211 4-digit LCD driver chip and LDC display. You will need to connect the icm7211 to one port of the 80196kb and consider the timing requirements of the data/digit-select lines.

Write a program which will repeatedly measure the value of a capacitor. You may assume that the capacitor will be in the range of .001 to .01 microfarad. The capacitance must be displayed numerically on 7 segment LCD displays. The value should be accurate to within a few percent. You may need to use a calibration capacitor during program design to get the accuracy down to 1%.

For extra credit, make the measurement auto-ranging so that a wide range of capacitances can be measured without either losing accuracy or overflowing a counter.

When you demonstrate the program to a staff member, you should show that measured capacitances are correct and be able to explain how you are sure of this.

Your written lab report should include:

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