Navigation system, navigation device and operating method thereof

A navigation system, comprising:

• a computer system configured to send requests to read displacement;
• and
• a navigation device, coupled to the computer system, and comprising:
• an I/O interface configured to receive the requests from the computer system and output the displacement to the computer system;
• an internal oscillator configured to generate a clock signal having a clock frequency;
• and
• a processor coupled to the 1/0 interface and the internal oscillator, and configured to
• count the clock signal between successive displacement being readout to determine a count value,
• generate the displacement every predetermined number of pulses of the clock signal, and
• calculate a difference that the count value is larger than the predetermined number of the pulses, and
• compare the calculated difference with a predetermined margin.

An operating method of a navigation device, the navigation device comprising an internal oscillator and a processor, the operating method comprising:

• counting, by the processor, a frame period using a clock signal of the internal oscillator;
• counting, by the processor, a polling period using the clock signal of the internal oscillator to output displacement every polling period;
• calculating, by the processor, an interval that the polling period is larger than the frame period;
• and
• adjusting, by the processor, the frame period when the interval is smaller than or equal to a predetermined margin.