Hi Robert,

I agree with mark_s, the resistor value in the diagram at http://robotgestation.com/SensorForce.html is incorrect. The 100k resistor with a 10uF cap will calculate to a 1 sec Time Constant (T). To yield a 10ms (T) with a 10uF cap a resistor value of 1k will be needed.

Since you are using ST inputs and reading the DS on for the 18F44K22 the logic High input minimum is .8 VDD. Using the Universal Time Constant charge curve, to reach .8 Vs (VDD) from 0v the time will be 1.6 (T). The maximum logic Low for the ST input is .2 VDD. The Delta of the Low and High is 1.4 (T).

If you use a 10k resistor with a 10uF cap (T) will be 100ms, so 1.4 (T) should work out to 140ms to rise to a minimum logic High on the PIC ST inputs.

Regards