Counter circuit and method

The present disclosure provides a frequency counter circuit for an electromagnetic solenoid plate with a pen. The circuit comprises a frequency counter counting module source terminal, a mobile terminal counting module, a logic determining module, a switch module, a signal capture module, a counter module, and a frequency control module. Wherein when the cumulative number of counted clock pulse source terminal module calculates a first clock signal reaches a first predetermined value, the switch module is switched to a receiving mode; the mobile end module calculates a second count of the clock pulse of the clock signal the cumulative number reaches a second predetermined value, the switch module is switched to a transmission mode. When the cumulative frequency module calculates the count value of the number of cycles reaches a third predetermined value, the frequency counter module as counting the first clock signal frequency, and the control module further obtains the frequency of the electromagnetic pen.