本文件是以stm32f103为硬件基础，以keil4编写，通过配置定时器的pwm捕获输入，从而达到测量矩形波频率和占空比的目的。-This document is stm32f103 hardware-based, keil4 written by configuring pwm timer capture inputs, so as to measure the square wave frequency and duty cycle purposes.