ECE-3120
Spring 2008
LAB 2 – Basic Arithmetic Programming
2/18/2008 Page 1 of 3 Lab 2
The purpose of this lab is to introduce you to basic programming with the 68HCS12
using assembler directives and arithmetic instructions. You will NEED to study the
directives and arithmetic operation instructions in Huang chapter 2 before attempting this
program.
PRE-LAB:
Prepare the pseudocode and the first draft of the program and calculate the expected
results (Sum, Average, Difference) by hand. 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:
• The program should start execution at address $1000.
• Use directives to create an array of five unsigned decimal byte values: 61, 200,
47, 188, and 26 stored in contiguous memory at locations $1500-$1504.
• Calculate the unsigned Sum of the five numbers and store this word at memory
location $1510.
• Calculate the unsigned Average of the 5 numbers and store this byte in memory
after the sum.
• Subtract the Average from the Sum and store the unsigned Difference (word) in
memory after the Average.
Procedure: First, use D-Bug12 to fill memory locations $1000 through $1600 with zeros.
Then assemble, download, and single-step through the program to debug it. Verify that
each value change, in registers and memory, 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. When finished debugging and executing, copy the entire terminal window output
and paste it into a Notepad or Word document for inclusion in the report. You may edit
out mistakes and repetitions before submission.
