在MSC-51的定时中T0和T1最常用，但像89s52中的T2却不怎么会用，本例子用T2实现精确1秒定时。,MSC-51 in the timing of the most commonly used T0 and T1, but T2 of 89s52 like how not to use, the example of T2 accurate with one seconds from time to time.