How many features?  How fast?
A 16F could implement the basic functions.  I assume there are floating 
point routines for the 16F available for download somewhere.

18F does have the C compiler and all... it's not a bad idea.  There 
aren't many 16F compilers because they're not very good- because the 16F 
series lacks some features which makes them difficult to compile for 
efficiently. 

How much battery voltage do you have, and how many batts?  The HD44780 
display alone will probably take a bit much for button batteries.  But 
the question is also voltage.  A 5v display needs 4 alkaline batts 
unless you use a boost regulator.

One thing to understand is you won't be able to compete with a regular 
calc for power consumption.  Those things have the integrated LCD drive 
and all and you will be taking 10x-100x more power with the best of designs.

dsPIC30F takes a LOT of power.
dsPIC33F takes a lot less, runs on 3.3v, but it's still probably too 
much.  And IIRC they have really bad Sleep current relative to say 18F, 
and that will hurt you a lot.

There's also the Microchip C18 compiler.  Personally, I have a big 
project that ran much slower on Microchip's C18 than it did with HiTech 
PICC18.  But I suspect that was a conflict with my coding style 
somewhere, I don't know, I did have the optimizations working and all.  
C18 is supposed to be as fast or faster performance, I've used it a lot 
but have never compared the two other than that initial project.  I'd 
recommend C18 over PICC18, just don't see a compelling reason to go 
third-party.

Danny

solarwind wrote:
> Hey all,
>
> I'm trying to build a scientific RPN calculator using a PIC microcontroller.
> It will be battery powered and for use in school. I'll be using it with an
> HD44780 based LCD character display and my own keypad.
>
> Basically, I'll need enough flash and RAM on the PIC to store all the
> functions a scientific calculator would have (sin, cos, tan, asin, acos,
> atan, log, ln, ee, e^x, pow, sqrt and so on). As for the second requirement,
> I'll need it to be as low power as possible as it will run on small
> batteries.
>
> Also, I'll be programming in C using HI-TECH's highly optimizing C compiler
> for the PIC. This compiler is amazing.
>
> I've already looked at the PIC 16F series. These seem to use low power but
> I'm scared that they will not have enough flash (and possibly RAM) for my
> application.
> Then I looked at the 18F series. These also seem to be low power and have a
> lot more RAM and flash.
> I was then tempted by the PIC32 series. These chips look perfect for my
> project. I'm now only concerned about the power usage of these things. Does
> anyone know the power usage for the PIC32 series?
>
> Anyway, I need advice. Which series of microcontroller should I chose for my
> project?
>
>   

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