Wrong Sine and Cosine results

[josefvs]

Hi All,

Using a 28X2, calculating both SIN and COS I keep getting 69 as the result and not 71.

Does anybody knows why?

Thanks

 

[jojojo]

Hem ... I think that Westaus has already reply to this answer ... But where ?

 

[Technical]

Please post your code, but it is probably due to the lookup table calculation.

The sin function returns a number equivalent to the sine of the value in degrees.
The system uses a 45 step lookup table in each quadrant, giving a very fast, and
reasonably accurate, result

 

[josefvs]

Using 28X2

main:
w0 = sin 45
sertxd (#w0,13,10)
pause 100
goto main

Thanks

 

[bfgstew]

Tried this in simulation and works, change sin value and works every time.

let w0 = sin 45
sertxd (cr,lf,#w0)

 

[josefvs]

Sorry didn't get it, which sin value was changed? I still get the same result.

 

[Technical]

>> 45 step lookup table.

So a lookup table step every 2 degrees, so 45 is processed as 44.
sin 44 = 0.69 X 100 = 69

next step is at sin 46