problem with 18F4550 clock speed

[alan]

Downside, CCS doesn't support PIC32, so you will have to use the Microchip compiler.

Regards

[Ttelmah]

[ckielstra]

The PIC32 processor line is building on the strong name of the PIC processor line but internally is a completely different animal. It is based on the MIPS processor core and as such not supported by any of the CCS compilers.

I think you are making a wise choice by moving away from the PIC18 processors to something faster. However, it also means you are moving away from this forum's target audience. As this forum is also hardware related we can discuss your question here but please be aware that we are getting off topic and that you might not get the best possible answers here (if your only tool is a screwdriver, then every problem looks like a screw).

We don't know what your project is about so with the limited specifications you have given it is difficult to give good advice. And why do you need a minimum of 24MIPS? Depending on the architecture this doesn't mean the same thing, for example 1 instruction on a 8 bit processor is way less powerful than a single instruction on a 32 bit processor. For example, multiplying a 32 bit value on a 32-bit processor can be done in 1 instruction time but will take over 200 instructions on a PIC18.
Note that some modern processors can execute more than 1 instruction per clock tick. So, if you specified the 24MIPS because you want to toggle an I/O pin than you might end up with a too slow processor.

We know you want to read a CCD with a 12-bit ADC at 1Msps. What are you going to do with the data after reading? This will be your next hurdle to take and now you are changing hardware platform it is necessary to think about it. For example, buffering the data would benefit from huge amounts of available RAM. 1 second data buffering requires 2Mb RAM, unthinkable on a PIC18 but less than 1% on some of the newer 32-bit platforms.

Generally: when starting a new design from scratch like you are I would be looking for one of the existing platforms. That'll give you a good head start because driver libraries for many external components are ready for use.
Some of the choices:
- Arduino ATMega based: Great, but tops at about 20MIPS, too slow for you.
- Arduino - ARM based: Good potential but quiet new and not a lot of choices in hardware. Arduino Due model has 512kb Flash, 96kbyte RAM and 84MHz (about 100 MIPS).
- Arduino others: Many companies have adopted the Arduino form factor with different processors. Good thing is that you can use many Arduino extension boards. Disadvantage is that the standard Arduino libraries are not going to work and you depend on manufacturer translated libraries. Your referenced Digilent ChipKit falls into this category with the PIC32 based on a MIPS processor, very different from the ARM and AtMega processors used in the official Arduino. Looking into it, this ChipKit platforms seems promising and is much more powerful than the other Arduinos.
- Raspberry Pi: cheap and very powerful hardware. Disadvantage is that the Linux OS requires some time to boot.
- mbed: great for quick prototyping. A small set of ARM based processor boards and good set of libraries. Design your prototype with given hardware and then for full production only re-use the parts you really need. I've one of these boards at home and they are good though at 48MHz a bit slower than the ChipKits.

[probeoil]