****************** Constant Definitions ******************
symbol  setting   = C.1   ;read voltage on pin 6
symbol  control   = C.2   ;PWM occurs on pin 5
symbol  frequency = 199   ;frequency fixed at 5kHz
symbol  num       = 5     ;slope numerator
symbol  denom     = 8     ;slope denominator
symbol  int       = 130   ;y-intercept (stalls below this)

;Note: The pot setting will be between 0 - 1023. For the
;motor used in the prototype, the duty cycle should
;range from about 15% to 99%. The relation y = mx + b
;transforms the former into the latter, where
;m=num/denom and b=int. Arrange these for integer arithmetic
;with no implicit order of operations.

;****************** Variable Definitions ******************
symbol  speed   = w0      ;current speed selected
symbol  prev    = w1      ;previous value

;********************** Main Program **********************
pgm:
  prev = 0
main:
  dirs = %00000100
  readadc10 setting,speed         ;check the setting
  speed = num*speed/denom+int     ;transform to useable range
  if speed != prev then           ;update if changed
    pwmout control,frequency,speed
    prev = speed                  ;save updated speed
  endif
goto main                         ;and start all over again
end