55:036
Embedded Systems and Systems Software
Spring, 2007
Fourth Laboratory Assignment
Due Dates:
Prelab: Tuesday, Feb. 27
Lab Report: Thursday, March 22
Objective:
The purpose of this lab is to gain experience with
interrupts, alphanumeric LCDs, and
pushbutton switches.
Lab Description:
For this lab, you will extend the simple waveform duty-cycle controller constructed in Lab 3. The functionality to be implemented is as follows:
F= 25 Hz
DC=75.6%
To receive full credit, your design must satisfy the following requirements:
Once your device is operating correctly, use a scope or logic analyzer to verify the accuracy of the waveform generation at the low end, middle, and high-end of the duty-cycle for each selected wave-form frequency.
Prelab:
Carefully review the class lecture notes and read Chapters 7 and 9 in the text to fully understand the basics of LCDs and PIC18x interrupts.
Carefully design your solution to the lab using flow charts and/or pseudo-code. Do not start writing assembly code until you FULLY AND COMPLETELY UNDERSTAND the solution.
To be submitted on Tuesday, February 27:
Pre-lab
report in the format specified in the Laboratory
Guidelines document. The pre-lab report should include a detailed
flowchart and/or
pseudo-code code description of your algorithm.
Lab Report:
Your
lab report (due on Thursday, March 22), should follow the general
format
described in Laboratory
Guidelines document. In addition, answer the following two questions:
1. What, if any, errors did you observe in the measured frequency and
duty-cycle of your waveforms
versus the values displayed on the LCD at the specified measurement
points? Identify the source of any
observed errors.
2. Are there any undesirable aspects to your design that impedes its functionality or performance? If so, explain how you would modify the design to fix these shortcomings.