Patent ID: 7472028
Filing Date: 2008-12-30
Classification: G01D,G01L,G01N,G01R,H03K

Abstract:
1. An apparatus for measuring a parameter, the apparatus comprising: a microprocessor having a plurality of pins; a sensor capacitor configured to change capacitance as the parameter changes, the sensor capacitor having a first lead electrically connected to a first pin of the microprocessor, and a second lead electrically connected to a second pin of the microprocessor; a first reference capacitor having a first lead electrically connected to a third pin of the microprocessor, and a second lead electrically connected to the second pin of the microprocessor; a resistor having a first lead electrically connected to a fourth pin of the microprocessor, and a second lead electrically connected to the second pin of the microprocessor; a second reference capacitor having a first lead electrically connected to a fifth pin of the microprocessor, and a second lead electrically connected to the second pin of the microprocessor a comparator configured to detect whether a threshold voltage has been reached; a timer, wherein the apparatus is configured to use the timer to measure how long it takes for: wherein the sensor capacitance is calculated using the formula: