说明：  A single sample is made on A10 with reference to internal 1.5V Vref. Software sets ADC12SC to start sample and conversion - ADC12SC automatically cleared at EOC. ADC12 internal oscillator times sample and conversion. In Mainloop MSP430 waits in LPM0 to save power until ADC10 conversion complete, ADC12_ISR will force exit any LPMx in Mainloop on reti.