功能：读取按键,控制LED闪烁。

首先对引脚选择寄存器PINSEL赋值为0，设置引脚连接GPIO。,然后对按键进行扫描，等到有键按下时，开始LED闪烁的程序。为了使LED有各种各样的闪烁结果，对其设计了一个表LED_TBL[]，并不断调用，对P0[7:0]这8个设置为输出的I/O口进行置一或清零，得到花样流水灯的效果。当接P0.14的按键按下时，LED闪烁状态会回到最初全灭至亮状态，然后继续按照其他花式闪烁。

-Function: Reads keys, control LED flashes. First　register PINSEL pin assignment to 0, set the pin connections GPIO. And then scan button, wait until a key is pressed, the program began flashing LED. In order to make a wide variety of LED flashing result, its design a table LED_TBL ​ ​ [], and continue to call for P0 [7: 0] This 8 is set to output an I/O port for a set or cleared get water lights pattern effect. When the button is pressed pick P0.14, LED flashing light will return to the original state all off, and then continue to follow the other fancy flashing.