Hi,
I don't know exactly how you expect it to work but if Iäm not mistaken your formula, when re-written looks like:
Code:
MotorDuty = ADCInVAL * 252 / 255 + 100
When ADCInVal = 1 Motor Duty will be 100
When ADCInVAL = 255 MotorDuty will be 352

Is that what you're seeing?

/Henrik.