MSP430F5527 ADC12内部参考电压没输出

请教各位老师\大侠\专家.前两周一直调试5527这款单片机ADC12部分.查找了TI的资料手册.在论坛上找了很多资料.参考代码.ADC12内部参考电压怎么设置都没输出.用万用表量都是0.3~0.7V左右.请赐教.

#include<msp430f5527.h>

void main()
{
WDTCTL = WDTPW + WDTHOLD;
P3DIR |=BIT2;
 P5SEL |=0x03;  //设置VREF
  P6SEL |=BIT4;  //A4输入
  ADC12CTL0 = ADC12ON+ADC12REFON+ADC12REF2_5V+ADC12MSC; // Turn on ADC12, set sampling time
  ADC12CTL2 |=ADC12REFOUT;                                          // set multiple sample conversion
 ADC12CTL1 = ADC12SHP+ADC12SSEL1+ADC12DIV1+ADC12DIV0+ADC12CONSEQ_2;       // Use sampling 
  ADC12MCTL0 =ADC12INCH_4;
    
 

  ADC12IE = 0x01;                           // Enable ADC12IFG.0
  ADC12CTL0 |= ADC12ENC;                    // Enable conversions
  ADC12CTL0 |= ADC12SC;                     // Start conversion                  // Start conversion

//  __bis_SR_register(LPM4+GIE);       // Enter LPM4, Enable interrupts
while(1)
{
delay(65000);
    P3OUT ^=BIT2;
}
}

中断程序没帖出...