MSP430F149的定时器B产生大约1ms的定时，使主程序退出低功耗模式。主程序执行一遍流程，再次进入休眠，等待下一次被唤醒。中断TIME_FA次后，改变定时器的定时时间。每次中断的时候翻转P4.1脚的电平，使LED熄灭或者点亮。-MSP430F149 generate approximately 1ms timer timing B, the main program to exit low-power mode. Main program execution once the process, re-enter dormancy, waiting for the next wake up. Interrupt TIME_FA times, changing the timing of the timer time. When each interrupt level flip P4.1 pin, LED, or light off.