Microchip Technology Incorporated
Fast frequency calculator

Abstract:

An apparatus includes a capacitor, a reference voltage, an input signal to be measured, and a frequency calculation circuit. The frequency calculation circuit is configured to select a capacitance value for the capacitor, charge the capacitor with the reference voltage, discharge the capacitor to a threshold voltage, and, based on a comparison of time to discharge the capacitor to the threshold voltage with a clock cycle of the input signal, determine a frequency of the input signal.