本次实验，使用TIM4产生一个1K的频率输出，用TIM1进行捕获。并测出频率计算

TIM1 的时基单元配置：关于TIM1的时基设置问题前文已经讨论过了。这里只有一点需要明确的，就是为了尽量减少更新事件，将TIM_Period设置到最大即0xFFFF。定时器时钟设置成2M，这样定时器的更新频率就是30Hz，不会造成两次捕获之间产生多次更新。-his experiment, using the TIM4 produce a 1 k frequency output, using TIM1 capture.And the measured frequency calculation

The TIM1 time base unit configuration: about the TIM1 time base set the problem mentioned above has been discussed.There is only thing need to clear is to minimize the update events, set TIM_Period to 0 XFFFF namely.The timer clock is set to 2 m, so that the update frequency of the timer is 30 hz, not cause between capture generates multiple updates.