STM32的TIM3通用定时器 输入捕获法测量频率 精确到1hz-STM32 of TIM3 general-purpose timer input capture accurate method to measure the frequency 1hz

实现STM32单片机的各种功能，包括USART通信，pwm波的输出，及输入捕获，及SPI数据通信，I2C的FLASH数据读取。-STM32 microcontroller to achieve a variety of functions, including USART communications, pwm wave output, and input capture, and data communications SPI, I2C the FLASH data read.