CodeWarrior for FreeScale trying to debug a simple program using the 56800E simulator

Question

I'm just getting started learning FreeScale DSCs (MC56F800x series). I've done some work with AVRs using both AVR Studio on Windows and Eclipse and avr-gcc on Linux. CodeWarrior is just not as intuitive.

Right now I'm stuck trying to debug a simple program. I start the debugger using the built-in simulator, but it never reaches the first line of main(). Instead it seems to get stuck in some initialization code (MC56F8006_init.asm), specifically this line:

    ;; Loop until OCCS_STAT[LCK0] = 1
wait_for_lock: 
    brclr   #OCCS_STAT_LCK0,x:>OCCS_STAT,wait_for_lock

I've let it run for quite a while and it never gets past this. It's obviously waiting for something, but what? You would think the simulator would just work... argh. Maybe there's some options I can change to make it pass this step?

I'm going to keep digging and will post an answer here if I find it first.

Updates:

Here's what I've found:

OCCS

• On Chip Clock Synthesis

brclr

• Branch if Bits Clear

The instruction loops until OCCS_STAT LCK0 is set. This register means the on-chip oscillator's PLL has locked (waits for clock stabilization).

I'm still not sure why the simulator spins forever on this line, and how I can solve this without resorting to hacking up the init code (which is part of the code library and not within my project).

Answer 1

I am not familiar with the part or the simulator, but it seems likely that the simulator is instruction-set-only and does not simulate the PLL hardware.

In most embedded development systems, the run-time startup code is provided as source and you could modify it (or rather make a local copy in your project and assemble and link that to override the default start-up). Alternately you could simply place a breakpoint in this loop, and advance the program-counter register to get it out of the loop. In many debuggers it is possible to attach a script to a breakpoint to do this automatically.