//1Mhz
BCSCTL1 = CALBC1_1MHZ; // Set range
DCOCTL = CALDCO_1MHZ; // Set DCO step + modulation */
/* //8Mhz
BCSCTL1 = CALBC1_8MHZ; // Set range
DCOCTL = CALDCO_8MHZ; // Set DCO step + modulation */
/* //12Mhz
BCSCTL1 = CALBC1_12MHZ; // Set range
DCOCTL = CALDCO_12MHZ; // Set DCO step + modulation*/
/* //16Mhz
BCSCTL1 = CALBC1_16MHZ; // Set range
DCOCTL = CALDCO_16MHZ; // Set DCO step + modulation*/
无论切换那个，用SMCLK输出DCO时钟，都是21.19MHZ，而且有点不稳定
