STM32 PWM 演示程序，使用定时器2-STM32 PWM demonstration program, using the Timer 2

基于STM32的定时器程序，一般可直接移植进系统，直接调用函数-STM32-based timer program, and can be transplanted directly into the system, call the function directly

测试STM32的定时器功能，主要用定时器5完成三路PWM波的输出，同时用定时器4完成两路波的检测，测试正确-Test the STM32 timer function, the main three-way done with the timer 5 PWM wave output, complete with timer 4 two-wave detection, the test correctly