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ModeratorPermalink Reply by Chris Anderson on September 7, 2008 at 11:37pm

I haven't looked at that math co-processor since we gave up on the Basic Stamp. What processor are you using? GPS shouldn't bring anything modern to its knees.

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Permalink Reply by Bruce on September 8, 2008 at 12:13am

Thats good news,

I had heard that advanced maths like those mentioned above were too much for the PIC.
I am currently using a 16F877 but considering upgrading to a processor with much more program memory and running it a bit faster than my current 10Mhz.
Thankfully the compiler I am using has sin, cos, tan as well as asin, acos, and atan therefore at least in theory the processor will be able to do the maths.

I found a website called math forum which lists a formula for calculating a target lat and long from a start lat and long as well as a heading and a distance.
Are still playing around with the calcs on paper and google earth to try them out pefore implementing them in code.
I have no experience in maths and floating point numbers in the pic, is the PIC capable of performing navigational calcs and guidance in a timely manner?

Thanks for your help Chris

Regards

Bruce

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ModeratorPermalink Reply by Chris Anderson on September 8, 2008 at 7:14am

Remember that you only have to do the calculations at most five times a second. And, as Jack mentioned, you can always use lookup tables.(which is what we do with ArduPilot running on a 20 MIPS Atmega.

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ModeratorPermalink Reply by Jack Crossfire on September 8, 2008 at 1:51am

U can work around the math by doing tricks like reading GPS in binary form. That gets you directly into fixed point base 2. Then you can determine angles and distances between points by doing iterative subtraction and lookup tables in fixed point. Personally stopped bothering with it and moved to 2 way radio for the FLOPS. If someone is trying to make a living on microcontroller coprocessors, by all means support their business.

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