Patent ID: 7453762

Claim:
An apparatus for auto frequency calibration for a transducer, comprising: an oscillator, for generating a system frequency; a micro controller, being coupled to said oscillator, for receiving the system frequency; a counting unit, being installed inside said micro controller, for generating at least a clock signal according to the system frequency; a transformer, whose input terminal is being coupled to the counting unit, for receiving the clock signal and transferring the clock signal to be a plurality of exciting signals, the output terminal feedbacks and couples the exciting signals to the interrupting signal input terminal of the micro controller, wherein said a plurality of exciting signals comprising at least a primary oscillating signal and at least a secondary oscillating signal and the amount of the clock signal equals to that of the primary oscillating signal; and a transducer, whose input terminal is being coupled to the transformer, and said transducer is being excited by the exciting signals to generate an output signal.