Problem With Math.h

[seg9585]

Hi all, was wondering if anyone could help me out with a problem I'm having:
I am trying to use Math.h for a few trig functions to be processed in the controller, and my program compiles perfectly fine, but immediately upon completing the upload to the RC, an ERROR text pops up with just hex symbols, and I get a code error led. This only happens when I try to use trig functions from Math.h such as tan(), asin(), etc. I thought at first it was a memory overflow of some sort but I seem to have plenty of memory left (I think). Note that this happens immediately after I upload the code, before its run (aka doesnt occur due to a runtime error from an invalid input value). Any help would be appreciated...

[Alan Anderson]

http://www.chiefdelphi.com/forums/sh...ad.php?t=42790

Your program is too big for last years' IFI_Loader to handle. Update it to v1.1.0 here: http://www.ifirobotics.com/rc.shtml#Programming

[Mark McLeod]

I usually see this when the data memory gets too full.

You can test by temporarily commenting out any large array declarations you might have just to see if it loads into the RC.

[seg9585]

I am using the latest version of IFI_Loader and have been connecting great with it, except for this one error when using trig functions. Also, I have tried commenting out just this single line and the code uploads perfectly, even when I add a bunch of extra memory-wasting arrays

[Jared Russell]

Look in the ChiefDelphi whitepapers for something about CORDIC - it's an integer-valued trig library that not only will solve your code size woes, but is faster too (since the PIC doesn't have a hardware FPU).

[seg9585]

Thanks, I found the CORDIC library and will test it tonight, but it appears that the function doesnt handle asin(). Do you know of any library extensions based on this library that would handle this?

[Jared Russell]

Well my first comment (question actually) would be, why could you possibly need asin()??? I'm assuming this is for range estimation, in which case atan() makes more sense, to me at least.

Secondly, CORDIC can by design do asin() - you need to slightly modify the code to get it to work, however.

Use the identity:
asin(x) = atan(x/sqrt(1-x*x))

[Jared Russell]

One other thing - if you look at the CORDIC implementation in the white papers, you can actually improve its performance twofold if you need both the sin() and cos() of an angle.

It actually calculates both simultaneously, but in the current design it discards whichever you don't need. Pass arguments by pointers into the function and you can get both at once.

[Greg Ross]

Originally Posted by seg9585

I am using the latest version of IFI_Loader and have been connecting great with it, except for this one error when using trig functions. Also, I have tried commenting out just this single line and the code uploads perfectly, even when I add a bunch of extra memory-wasting arrays

Are you SURE you have the latest version? Notice the very subtle difference between IFI_Loader v1.1.0, which is the very latest version, and IFI_Loader v1.0.10, which I suspect you may be using.

[6600gt]

All of the math.h functions need a huge code space, because there are a bunch of long floating point #defines.

[seg9585]

Oops, sorry about that everyone. I was using what I THOUGHT was the new 2006 version, because I installed v1.0.10 to learn the controls on last year's bot, but downloaded v1.0.12 to connect to this year's. Anyway I installed v1.1 and it seems to work fine now.
By the way, for anyone else who is using tan(CameraAngle) to determine horizontal distance to the target using the stock camera mount, do you get decently accurate results? When the light is decently far away, 1 change in servo tilt value obviously equals a much greater change in reported distance. I am thinking of using a different servo with more steps...

[Mike Betts]

Originally Posted by seg9585

... I am thinking of using a different servo with more steps...

Although you can have as many servos as you wish, they all have to be the HITEC kit servo <R43>.