Patent ID: 9229546
Filing Date: 2016-01-05
CPC Classification: G06F

Claim Text:
1. A frequency counter adapted to an electromagnetic board and an electromagnetic pen, and disposed in the electromagnetic board, comprising: a source count module, used to receive a first clock signal, and the source count module setting a first predetermined value; a motion count module, used to receive a second clock signal, and the motion count module setting a second predetermined value, wherein the electromagnetic pen outputs a second electromagnetic signal provided for the electromagnetic board as in discharge mode, and then generates the second clock signal; a signal-capturing module, directly coupled with the motion count module; a frequency-counting module, directly coupled with the signal-capturing module, setting a circular number; a control module, directly coupled with the frequency-counting module; and wherein, the signal-capturing module generates a gate enable signal to the frequency-counting module in response to the clock signal, so as to enable the frequency-counting module to count a first high-frequency clock signal; the frequency-counting module outputs number of counting the first high-frequency clock signal to the control module when the cumulative circular number reaches a third predetermined value; the control module calculates a frequency of the second electromagnetic signal according to the number of the first high-frequency clock signals; the first high-frequency clock signal is a frequency-doubling signal of the second clock signal.