WWDG+LCD1602秒表实验；* WWDG + LCD1602 秒表实验 *两个按键中断方式控制，计时精确到10ms *key1--Start/Stop---PA8(板子上User键) key2---Clear---PC13(板子上Tamper键) *LCD1602接线：D0~D7--->PD[0..7] RS->PE0 RW->PE1 E->PE2(外部接上拉电阻到5V) *by 追梦 2011-4-8 *change by:追梦 2011-

stm32 pwm 定时器 计数器等功能的集合，可以实现pwm输出，外部信号计数，定时器开关等功能-ststm32 pwm timer counter is a collection of functions can be achieved pwm output, an external signal count, timer switches and other functions.

stm32实现高精度频率测定，共两种方法 捕获法（可精确到0.001Hz） 定时器中断法（可精确到0.1Hz）-stm32 achieve high precision frequency measurement, a total of two methods Capture (accurate to 0.001Hz) Timer interrupt method (accurate to 0.1Hz)

led on off with waiting counter