memarian said:
Thanks for your help.LPC3180 has very attractive features but i can't use it.
it has many features that i don't need them like as DMA Controller,DDR Ram
interface & ...
Extra features don't matter at all. If it's the best bang for the buck then that's it.
Haven't needed it myself, but looking at the datasheet PIC24 does look pretty interesting..
PIC24FJ128GA
• 17-bit x 17-bit Single-Cycle Hardware
Fractional/Integer Multiplier
• 32-bit by 16-bit Hardware Divider
• 16 x 16-bit Working Register Array
16 cycles for the 16 bit divides though.
Got some on the desk, just working on other things ATM..
Realize no one can be much of any help without knowing something about what you really need to do. Most real world tasks with any real kind of computation have dedicated chips that do an easier and better job. You've changed requirements from just needing FP multiply and divide (which you likely don't really even need with proper software anyway..), to really fast operations of the same. Hiding what you want to do is fine if that's what you want, but realize no one will be able to help you much or point you towards better methods if that's the case. No way to make even a good guess at what controller without some reasonable idea of how much computing power is really needed. You'll basically have to get up to speed a bit on 6 or 8 candidates and decide for yourself..
I'd expect you'll end up overshooting by a factor of 4 to 10 or more the minimum controller to do the job. Not too big a deal though these days with so many cheap controllers, likely the cost won't even be 50% or double cost over the cheaper controller.
ARM for ~$10 sounds like a deal too. If you're complaining about the extras because you want one cheaper without add-ons then don't bet on it. It doesn't make any sense to build a complex unit with nothing else, you won't see a 32 bit multiplier 8 pin PIC for a reason. The one with the extra parts will be the cheapest, because it's what most people want. The 'extra' actually has a negative cost for you, it makes your price lower from being what the larger majority want in their controller. Won't make sense to pay more to leave it out, except in rare low power circumstances.
Realize that that you only want a SPI or UART is what makes me think you have no real need for anything near what you're asking. A lower end 16F or 18F series PIC could easily outperform anything you're likely to get in and out of a serial port. Not that it can't be done with encryption algs etc, but likely you're not doing anything near that complex, you're just not up on the ways to do higher math in a lower processor and looking for a shortcut. That's fine too, but the extra crap is all going to come along with the extra math functions. You're going to have waste with getting the FPU or math unit etc, which again probably includes even buying the FPU in the first place. But certainly easy and still cheap enough, just get past the idea of wasting large parts of the controller. It's simply cheaper and easier to waste parts of a cheap large controller than find a limited but still with FPU version..