说明：  展示了msp430f14x单片机的AD操作
(A single sample is made on A0 with reference to AVcc. Software sets ADC10SC to start sample and conversion- ADC12SC automatically cleared at EOC. ADC12 internal oscillator times sample (16x) and conversion. In Mainloop MSP430 waits in LPM0 to save power until ADC12 conversion complete, ADC12_ISR will force exit from LPM0 in Mainloop on)