Re: performance of the MPC55XX compared to a TI67XX

Dear Todd,

Your question is a quite different to answer.

> The topic of MHz vs MFLOPs vs MMACs and RISC vs CISC is confusing 
> enough and I couldn't find anything specific to the subject on the 
> freescale website.

Unfortunately this are important questions. As you might know, RISC processors execute quickly but "simple" instructions, while CISC processors execute more complex instructions but might take longer to do so. Caches play an important role in performance so this can't be ignored either. I think the TI family you mention is VLIW, which means that it's a pain (i.e. almost impossible) to program in assembly should you need to, but hopefully this is not an issue. TI measures this in MMACS, exactly for this reason: because for VLIW processors, they can "cheat" with the benchmarks more. In practice, you can't never fully utilize the whole pipeline of VLIW processors so that is purely theoretical. Floating point is another important (maybe deciding factor) to consider. Some CPUs support no floating point, others single point only (MPC5554), others double precission. If your applications require
 s double precission, I *highly* recommend you to choose a double precission CPU, whatever you choose. For avionics and hard real-time applications I recommend you getting a CPU without cache or disabling it altogether since this could lead in unexpected run-time issues (unpredicable missed deadlines)

The reason why the MPC family is taylored torwards automotive is because of the TPU (this is something that allows you to control simple actions that require very precise timing, like engine in control and it is done with a subcore of the MPC), and lots of I/O.

TI family of DSP as taylored for digital signal processing applications. My rough advice is that if you are doing DSP apps and have experience with TI, then stick to TI. If you need more I/O, consider the MPC family.

So my advice is to first make a list of requirements
- Math precision
- Type of application
- Operating system support
- Budget (should you need new compilers, OS)

And then choose a processor family. Sorry if I didn't answer your question, but it is not an easy one. Benchmarking is a very fuzzy thing. You could buy cheap evaluation boards and if you are running rapid prototyping systems (i.e. Matlab embedded coder, dSpace TargetLink, etc) you test them with minimal effort). These tools usually offer run-time analysis capabilities as well.

Reagards,
-Julian