The PIC32 will do what you want, run very quickly, will consume very little power, and will be easy to program for (since you don't have to worry about banking, strange memory issues, etc). To get low power out of any microcontroller you're going to have to program for it, though. In your case, the calculater should have an interrupt on change for the keyboard and only perform work immediately after a keypress. Using this model the calculator will be sleeping 99.9% of the time, and the processor will be consuming very little current. However, most HD44780 style displays consume quite a bit of current and if you use an intelligent keyboard (like a PC keyboard) rather than a matrix keypad of your own design then that too will consume a huge amount of power. You might want to look at graphical LCDs designed for cell phones. Go for monochrome without backlight for the lowest power - http://www.sparkfun.com/commerce/product_info.php?products_id=8428 - This unit consumes 1.2mA max at 3.3v, for instance. If you want to stick with an HD44780 style display, use a low current one, such as this one http://www.newhavendisplay.com/index.php?main_page=product_info&cPath=3_111&products_id=650 that consumes 1mA max. There's no backlight, but the backlight is going to break the power bank. However: Skip all that for now. You're taking on a pretty big project, even though it seems conceptually simple. Go ahead and buy a PIC32 kit for $50, it'll include everything you need to get started, and you can program you calculator with the computer acting as the keyboard and display (use the debugging interface). You don't have to do any additional hardware work. Once you've got it doing the calculations you want, hook up a current meter and modify the program so it sleeps when it's not doing any work. It should consume less than 1mA on average, though when it's working it'll peak at a few mA, but that should happen so quickly your meter probably won't register it. Once you've gotten that far, you can start looking at adding a keyboard and display. But it may surprise you how long it takes to get that far, so start slow and learn the processor first. If you do go this route, use a low power LCD display, a matrix keypad, low power methods on the processor, then you can run the whole thing off of 2 CR2032 button cells in parallel. Good luck! -Adam On Fri, Dec 5, 2008 at 1:31 AM, 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? > > -- > ..::[ solarwind ]::.. > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- Please rate and vote for my contest entry: http://mypic32.com/web/guest/profiles?profileID=50331 -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist