Overview

The purpose of this lab is to become familiar with the development environment and development tools used throughout this course.

Problem Statement

We will use the following program to begin our investigation:

Comments are preceded by a semicolon (;). All text on a line after a semicolon is ignored by the assembler

• Line 24 includes a definition file (this is necessary for all assembly files)
• Lines 26 and 27 define global constants
• Line 29 defines a register to be used as a variable
• Line 33 declares start of the data segment
• Line 34 has the data segment start at 0x60
• Line 35 reserves one byte in SRAM and labels the address with data
• Line 37 declares the start of the code/program segment
• Line 38 has the next instruction start at 0x00
• Line 39 defines a relative jump (rjmp) to Reset, which is a label later in the source
• Line 41 has the rest of the code segment start at 0x2A
• Line 42 defines the location of the label Reset (note that all labels must be in the left-most column and end with a colon (:))
• Lines 43 and 44 set PORTB to output by storing a 0xFF into DDRB
• Lines 46 and 47 set data to zero
• Line 48 outputs r20 on PORTB
• Lines 50-53 implement a waiting loop by loading a register (counter) with time (line 50), decrementing the register (line 52), and branching if not equal to zero back to line 52.
• Lines 55-57 increment data, which is in SRAM
• Line 58 outputs r20 on PORTB
• Line 60 jumps back to start, which is line 48

You should use the following general layout conventions for your assembly programs:

• left-most column is reserved for labels only (unless a line is comment only)
• second column is reserved for instruction
• third column is reserved for operand(s)
• fourth column contains (optional) comments, preceded by a semicolon

Pre-laboratory investigation and report (due before the beginning of week 2 lab)

• Determine the cycle count for every instruction of the above program. The cycle count can be found in the instruction set manual (available online or as help file in AVRStudio).
• Calculate the total cycle count and time between line 47 and line 54. The frequency of the microcontroller oscillator is 8MHz.
• Read the Getting started programming the Atmel ATmega32 in assembly using AVRStudio document.

Laboratory investigation and report (due before the beginning of week 3 lab)

• Modify the program so that the changing output can be seen. Hint: add one or two more waiting loops around the already existing waiting loop.
• Assemble and simulate the program.
• While simulating, add all variables used in the program to the simulator watch.
• Make at least three different screen shots of the simulator at different stages of the program.
• Download and run the program on the hardware board.
• You should submit (Make sure your name is on every page):
  • A copy of the modified source program
  • A copy of the list file
    • Make sure "Create List File" is selected in Porgram -> Assembler Options
    • Add .nolist before the .include "m32def.inc" and a .list after in your .asm file
  • Screen shots from the simulation phase

Acknowledgment

This laboratory was developed by Prof. Bill Barnekow.

© 2001-2007 Dr. Christopher C. Taylor

Office: L-343

Phone: 277-7339