ACLK = SMCLK = MCLK =XT1 =32768

int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop watchdog timer

P1DIR |= BIT0; // ACLK set out to pins
P1SEL |= BIT0;
P2DIR |= BIT2; // SMCLK set out to pins
P2SEL |= BIT2;
P7DIR |= BIT7; // MCLK set out to pins
P7SEL |= BIT7;

P5SEL |= BIT4+BIT5; // Select XT1

UCSCTL6 &= ~(XT1OFF); // XT1 On
UCSCTL6 |= XCAP_3; // Internal load cap
UCSCTL3 = 0; // FLL Reference Clock = XT1

// Loop until XT1,XT2 & DCO stabilizes - In this case loop until XT1 and DCo settle
do
{
UCSCTL7 &= ~(XT2OFFG + XT1LFOFFG + DCOFFG);
// Clear XT2,XT1,DCO fault flags
SFRIFG1 &= ~OFIFG; // Clear fault flags
}while (SFRIFG1&OFIFG); // Test oscillator fault flag

UCSCTL6 &= ~(XT1DRIVE_3); // Xtal is now stable, reduce drive strength

UCSCTL4 = SELA_0 + SELS_0 + SELM_0; // SMCLK = MCLK =ACLK = LFTX1

}

注意劃紅線的語句，要用等號賦值。因為默認 SELS 和SELM的值是不為0的，所以用或賦值的話會出錯。