Problems with NullZone

[the_undefined]

Hey Guys,

we have a problem with a scale function that we wrote in order to have a rectangular NullZone where the joystick is deactivated. Once the Joystick get s out of the Zone (for example p1_x > 147) then we want to scale the new value over the full range of the output (here from 147 - 255 TO 127 - 255) in order to not start with like 20 speed when we get out of the zone.

The function that we came up with works in calculators and other c-Compilers but not with the RC so I hope somebody could help us with this:

Here is the Function:
unsigned char scale ( unsigned char sNum , // Value to Scale
unsigned char sMin , // Old Min Value
unsigned char sMax , // Old Max Value
unsigned char eMin , // New Min Value
unsigned char eMax) // New Max Value
{
unsigned char eNum = (( sNum - sMin ) * ( eMax - eMin ) / ( sMax - sMin ) + eMin);
return eNum;
}

And here where we call it (N_ZONE_X = 40):
(int)scale((unsigned char)p1_x, 127 + (N_ZONE_X / 2), 254, 127, 254);

the value that we get is always either 127 or 254 but never stuff in between so we're kinda confused : ( ...

Thanks,

bye

Felix

[AIBob]

In your code you may not be typecasting enough, when you are subtracting the two unsigned characters there may be some problems in that code, try this:

unsigned char eNum = (unsigned char) ((( (signed int)sNum - (signed int)sMin ) * ( (signed int)eMax - (signed int)eMin )) / ( (signed int)sMax - (signed int)sMin ) + (signed int)eMin);

[the_undefined]

Originally Posted by AIBob

In your code you may not be typecasting enough, when you are subtracting the two unsigned characters there may be some problems in that code, try this:

unsigned char eNum = (unsigned char) ((( (signed int)sNum - (signed int)sMin ) * ( (signed int)eMax - (signed int)eMin )) / ( (signed int)sMax - (signed int)sMin ) + (signed int)eMin);

Ok I'll try that tomorrow, thanks for your help ... C Typecasting makes me just crazy ^^, I'll be so happy when I'll finish our Teams Homepage in PHP after Shipping Date you can't imagine : ) ...