ECE-3120
Spring 2004
LAB 2 – Basic Arithmetic Programming
The purpose of this lab is to introduce you to basic programming with the 68HC12 using
assembler directives and arithmetic instructions. You will NEED to study the directives
and arithmetic operation instructions in Huang chapter 2 before attempting any
programming. The code is fairly simple to write since it is very similar to what you did in
Lab1.
PRE-LAB:
Prepare pseudocode and the first draft of the program and calculate the expected results.
This must be completed before coming to the lab and shown to the lab instructor at the
start of the lab session.
Approved: Lab TA _____________________ Date ____________
PROGRAMMING ASSIGNMENT:
Write a fully-commented program for the HC12 board, including appropriate directives
and labels for memory operands and constants, called Arith.asm. The program should do
the following:
• Have an array of five unsigned byte values: 61, 200, 47, 188, and 26 initially
stored in memory starting at location $900.
• Calculate the average of the 5 numbers and store this byte in memory location
$908.
• Calculate the sum of the first 4 numbers and store this word in memory location
$90A:90B.
• Subtract the average value from the sum and store the difference (word) in
memory location $90C:90D.
Assemble, download, and then single-step through the program to debug it. Write an
execution trace list, showing each instruction and recording every change in value of all
registers (including CCR) and/or memory after each instruction. Verify that each change
is correct and that the final values of average, sum, and difference are correct. Then reset
the processor, download the program again, run it at full speed until it stops, and verify
that the final values are still correct.
Approved: Lab TA _____________________ Date ____________
2/13/04 Page 1 of 2 Lab 2
