ECE473 Lab3:

Purpose:
  *Use interrupts to time sample switches and display. 

Project Specifications: 
  *Functionally just like lab2 but implemented with interrupts.  
  *Using the protoboard and pin strip headers, make a way to
   connect Vdd and Gnd for the led and button board, and the enable
   inputs to the 3-to-8 decoder. Lower nibble of PORTC are to be left open. 
  *Use your schematic diagram from lab2.
  *Port A is still used to sense the switches and sink current from the LEDs.
  *Port C upper nibble will select the digit to display. 

Software Notes:
  *Copy over the Makefile from lab2 and edit project name. 
  *I recommend writing out pseudo-code or a flowchart for your lab3 code. 
   Don't start by first writing code. That will only slow you down.
  *Use of interrupts timers is mandated; no software delays anywhere. 

Testing:
  *Test and debug code and hardware. Write simple test software first. 
   You can add the rest of your code later.

Turn into COE TEACH: 
  *Your C code.
  *The file to submit is created with the Linux tar command:
     tar -cvfz lab2.tar.gz file1 file2 file3 .....
   This would create a single file "lab2.tar.gz" from the listed files after
   compression by gzip. 
   Synopsis: (tar)tape archive, (c)create, (v)verbose, (f)use given tar file name, 
             (z)compress with gzip

You will demonstrate the functionality of your board and code in lab. 
  
Grading:
  *Circuit function                   +70% (demo system in lab)
    -performs as expected
    -if display"jumps"                -deduct 10%
    -dim display or it flickers       -deduct  5%
    -other abnormality                -deduct  5%

  *Documentation                      +30%
    -code well written, commented, including test code     
    -poorly commented code            -deduct 10%

Lab weighting = 0.15