Homework 1

This assignment should be handed in before class on Thursday Feb 19, 2009. Handin is on the CADE lab machines using commands like this:

  handin regehr hw1 filename

Where "filename" is the name of a file to hand in. The exact names you should use are given below.

You'll need to install version 4.7 of the "special edition" of CodeWarrior for HCS12(X), which is available from the FreeScale web site. Of course you can just use a lab machine where this is already installed.

We'll discuss this homework in class on 2/10.

1. In class we discussed how the Timer_Wait function from slide 15 of Lecture 4 is broken. Write a correct version and hand in a file containing the code as prob1.c. Include any necessary header files. The file should be compilable using CodeWarrior for HCS12 in a project for our chip (to create such a project see the Lab 1 writeup). Also handin a compiled, disassembled version of your function as prob1.asm.
2. Create a new code warrior project for your chip. Next, by pressing Alt-F7 in CodeWarrior and then moving to "compiler for hc12", tell the compiler to optimize for maximal code density (look under "smart sliders"). Type in the "Mealy FSM" from Lecture 4. Compile it and (using the manuals) figure out how many cycles it will take to execute the main loop, in the worst case. In other words, pick an instruction in the main loop and figure out how long in cycles -- at most -- it will take the CPU to reach this point again. Timing information is available in your manuals. Handin a dissasembled version of the application where instructions in the main loop are labeled with their cycle counts. Call this file prob2.asm.
3. Repeat the exercise from problem 2, but this time reimplement the Mealy FSM without using function pointers (how you do this is up to you). Call the file you handin prob3.asm. The effect of the FSM should be exactly the same as the version from lecture.