基于单片机控制系统，设计一款频率计，具体为蔡用定时器1定时，用外部中断一计数,每中断一次,count加一，并用P1口接的八个发光二极管显示。-Microcontroller-based control system, design a frequency counter, specifically for the CAI with the timer 1 timer, an external interrupt one count each of break time, count plus one, and then with the P1 port of the eight light-emitting diode display.