This is a multi-part message in MIME format. ------=_NextPart_000_0031_01C157FB.D98897E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Refer to the attached GIF. For any given Sensor voltage from 0 to +5 you want a corresponding PWM from the PIC output that when "mixed" via R1 and R2 will result in an input to the PIC that just drives over the "HIGH" threshold. Note that the value for R2 may have to be adjusted somewhat from the value shown, depending on the actual threshold value. R2 may have to be smaller than R1. R3 and C1 are not critical in value, but must be chosen so that the voltage appearing at their junction for a given PWM frequency results in a voltage with little ripple. The minimum C1 is a function of the PWM frequency and R3. In this case we are using the input high threshold of the PIC as a sort of comparator trip point. While this is not the best way to do things, it does have the advantage of using very few parts. The PWM is "swept", and the PWM value at the point where the input switches from low to high can then be used to determine the actual sensor voltage. This can be done using a look up table or a mathematical formula. Fr. 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