The purpose of this lab is to acquaint you with the embedded software development tools that you will be using throughout the quarter. You may work in pairs and submit a group report.
In this lab, you will assemble, link, simulate, download, and run a program.
Begin by getting the assembly source file from this web site: lab1.s. The .s filename extension signifies human-readable assembly language.
Since you will need them for this and future labs, install the tools available from the tools page. Skip section V, since it applies to the MSOE briefcase, which we are not using.
Next, assemble the program from a command prompt (be sure to see the
tools page for instructions on how to open a properly configured command
prompt window) by entering:
as -o lab1.o lab1.s
The options (text that follows the “as” assembler command) tell the assembler to:
The following commands will tell you some interesting information about the object file. You don’t need to know what all of this means yet, but be sure the examine the output to see what you can learn. Check with your instructor if you have any questions.
Next, run the linker with the command:
ld -T ../fox11w.x -o lab1.elf lab1.o
The options mean:
fox11w.x sets up memory as follows…
Create a human-readable listing of your ELF executable with the command
objdump -d lab1.elf > lab1.rst
Question: Where does the data area end up? (Hint: Inspect the .rst file and see if you can figure this out – feel free to ask the professor for help.)
Create an S19 format executable for use by Wookie and WBUG11. S19 is a simple format that specifies which values to store at which addresses and little else. It is not easy for a human to read (take a look and ask your instructor if you are curious about the details), but is conveniently formatted for loading into the HC11’s memory by a program like WBUG11.
objcopy -O srec lab1.elf lab1.s19
Now you are ready to use the executable (lab1.s19). Run the executable on both the Wookie Simulator and the actual Fox11 hardware.
Skim Dr. Sebern’s Introduction to the Wookie 68HC11 Simulator.
Start Wookie. After running Wookie for the first time, .s19 files will be associated with it, so you can double-click them to open them in Wookie.
| Select File | Load and locate and double-click on your .s19 file. |
You will see a dialog box. You will need select “Rug Warrior Expanded” mode and change the starting address for the code to 8400 to match your program.
A dialog appears asking you the format of your listing file. Accept the default of GCC3.
Next press the "M68HC11 CPU" button. This will let you examine the registers.
You can also press the "Browse Mem." button, to allow you to see the data in memory. Scroll down to the data memory address you found in the listing file.
On your Fox11, ensure that J15 is in the Wytec position.
Connect your Fox11 to power. It will turn on as evidenced by PB0 illuminating.
Connect your serial cable between your computer and your Fox11’s upper right serial port (P2).
Press Reset on your Fox11 and note that PB0 blinks to acknowledge the reset.
Start AsmIDE.
Enable the Wytec tools by selecting View | Options | Wytec HC11 Options (tab) and check Enable Tools.
Under the Build menu, select “Wytec 68hc11 Tools”.
Click “…”, locate your S19 file, and then click “Select this file”, followed by “Debugger”.
You should observe a console window open. After several messages, you should see “lab1.s19 downloaded.” Do not be concerned with the messages about the missing .sym and .par files. You can run full screen and in color by pressing Alt+Enter (press Alt-Enter to return to windowed mode).
Press “g” and notice that the downloader/debugger enters the “Go” command for you. It is now waiting for an address in memory. Type “8400” (this is in hexadecimal - no base prefix is needed) and press Enter.
The Fox11 runs at 2 MHz, so the program will complete virtually instantaneously. Hit ESC and examine the data memory (use the Dump command as described in the help, accessible via F1).
Now, observe the program running step-by-step. Hit ‘R’ to modify registers inside the HC11. You will be prompted for a “PC” value. Enter 8400, the start of your program. You are then prompted for a “Y” value, but press escape as you do not need to modify anything else.
Press ‘N’ to have your program take a single assembly language step. Repeat this several times, noting how the PC (program counter, address where an instruction is about to run) changes, along with ‘Y’ (counted characters) and ‘X’ (address of the character being examined).
Try some of the other features in the downloader/debugger, asking your instructor for assistance as needed. Do not worry that much of this is unfamiliar right now.
Be sure that you answer the following questions in your report. Find the answers in your .rst file and by inspecting memory in Wookie and/or your Fox11 via AsmIDE/WBUG11.