Cordic trig assembly code for PIC18f

[B-O Eliasson]

Hi !
I'm trying to write a program to calculate sunrise and sunset. The pic is 18F2550 and I'm using long variables and PBPL. I've tried to use the TRIG.INC but it seems that I cant use it in PBPL, Error: DIV32. Is there a way to rewrite the program so that it will work with PBPL?
I'm using Picbasic Pro 2.50 and MPASM 8.15.
Bernt-Ove

[B-O Eliasson]

The problem is solved. I found another version of trig.inc in post 13, and it works well for me. I have to put the word variables x,y into long variables before doing any calculations on them.

[ScaleRobotics]

The problem is solved. I found another version of trig.inc in post 13, and it works well for me. I have to put the word variables x,y into long variables before doing any calculations on them.

That's a good bare bones cordic version as long as you don't mind manipulating the radians. So you could either use that and do math to your liking, or you could use TrigL , which you can find with my tilt example here: http://www.picbasic.co.uk/forum/cont...-axis-g-sensor . If you use TrigL.inc, you would probably want to add a line to replace goto main with goto overcordic
and at the end of the TrigL.inc add a line overcordic:

Keep us posted, I'd love to see your project.

Walter

[chrisshortys]

Hi Walter, I have been looking at this for some time now and keep coming back to this post. I am actually attempting to do a similar project to the tilt sensor project which you have built only on a single axis. I believe I am almost there now and just need a few pointers! I am looking at your code atn2. the following is the equation i require to solve: tan-1 ((zresult - calval)/SQR ((5017 - calval)^2 - (zresult - calval)^2))
Now from reading your posts would I be right in thinking that if i do the following:

x=0
 y= ((zresult - calval)/SQR ((5017 - calval)^2 - (zresult - calval)^2))

call atn2

Am I right in thinking that this would convert my equation as I am not interested in the hyp or does the x vaule come into play?

[readitaloud]

Hi,

I am using your TRIG.inc in a small program. The values appear correct from (ang) = 0 to 9000, 0 to 90.00 degrees. For values, 9000 < (ang) < 18000 ,the
values for x and y appear to switch. As an example with an (ang) value of 8900 or 89.00 degrees I receive a value back x = 29995 and y = 525. This seems correct.
For an (ang) value of 9100 or 91.00 degrees I receive back x = -523 and y = 29995. For 91.00 degrees I would expect x = 29995 and y = -523 ?

- Martin