[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);