HELP Using the uF-MPU math coprocessor

Brian Carpenter

i have an equation that i need to solve with the math coprocessor.· anyone have experience with this?

The math is

Altitude = (10^(log(P/S)/5.2558797)-1)/-6.8755856*10^-6

Altitude is in Feet

P is a variable from an ADC

S is a constant that could just be added to the equation.· it should be 208

Any ideas on how to do this?

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It's Only A Stupid Question If You Have Not Googled It First!!

metron9

Remember, a microprocessor uses addition and subtraction to do math functions. write your equasion out long hand, convert the multiplication to a for next addition loop, the division to a subtraction loop, the log function to a lookup table. That's how under the hood the basic stamp processor works as well as the coprocessor, the coprocessor is optimized hardware that will do what software in a stabdard microprocessor does.

If you don't have a time critical application, that could work.

Jon Williams

If you're using the um-FPU then I strongly suggest you download and use the IDE -- it makes life so much easier (after you spend a few minutes learning how to use it).· What I like about the um-FPU IDE is that it lets one download the equations into the device so that you don't need a lot of Stamp code to deal with the conversion.

I wrote about the um-FPU in my column: http://www.parallax.com/dl/docs/cols/nv/vol6/col/nv123.pdf

I've attached a screen shot of the latest IDE with your equation installed.· It compiles ... you'll have to determine if it works.

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Jon Williams
Applications Engineer, Parallax