MSP430AFE253的24位AD不稳，底部8位数据飘的厉害？

我最近在用430AFE253，遇到些问题。

1脚输入电压大致0.6 ，2脚也是0.6，AD参考电压用内部1.2V。想用他的1024次过采样

问题1

1024次过采样的数据怎么处理，通过移位相加操作后，得出29位数据，去掉底部5位就是24位AD的数据输出吗？

问题2

预置寄存器做什么用？ 模拟输入使能寄存器在253的头文件中找不到，怎么控制，怎样使能外部输入。

问题3

采样数据不稳定，底部8位飘的厉害，帮忙看看代码有什么问题吗

 #include "msp430afe253.h"
#define   Num_of_Results   9

/* Arrays to store SD24 conversion results */
unsigned long Ch0results[Num_of_Results];
unsigned long Ch1results[Num_of_Results];
unsigned long Ch2results[Num_of_Results];

unsigned long Ch0results2[Num_of_Results];
unsigned long Ch1results2[Num_of_Results];
unsigned long Ch2results2[Num_of_Results];

unsigned long Ch0results3[Num_of_Results];
unsigned long Ch1results3[Num_of_Results];
unsigned long Ch2results3[Num_of_Results];
void main(void)
{
      volatile unsigned int i;                  // Use volatile to prevent removal
      
      WDTCTL = WDTPW + WDTHOLD;          // Stop WDT
      P1SEL |= BIT0;                     // Set SMCLK at P1.0
      P1SEL2 |= BIT0;                    // Set SMCLK at P1.0
      P1DIR |= BIT0+BIT3;                // P1.1 and P1.0 = output direction
      
      //BCSCTL1 |= XT2OFF; //默认关闭XT2
      //BCSCTL2 |= SELS+SELM_3;                 //SMLK=VLOCLK MCLK = VLO
     
      BCSCTL3 |= LFXT1S_2;               // LFXT1 = VLOCLK
      BCSCTL2 |= SELM_3;                 //MCLK = VLO
      
      SD24CTL = SD24REFON + SD24SSEL_2 + SD24XDIV_3;          // 1.2V ref, SMCLK
      SD24CCTL0 |= SD24GRP+SD24UNI +SD24LSBTOG + SD24OSR_1024;              // Group with CH1
      SD24INCTL0 |= SD24GAIN_2;

      SD24CCTL1 |= SD24GRP+SD24DF + SD24OSR_1024;              // Group with CH2
      SD24CCTL2 |= SD24IE+SD24DF + SD24OSR_1024;               // Enable interrupt
      for (i = 0; i < 0x3600; i++);             // Delay for 1.2V ref startup
      
      SD24CCTL2 |= SD24SC;                      // Set bit to start conversion
      __bis_SR_register(GIE);       // Enter LPM0 w/ interrupts
      while(1);

}
#pragma vector=SD24_VECTOR
__interrupt void SD24AISR(void)
{
 //     static unsigned int index = 0;
    
      switch (SD24IV)
      {
      case 2:                                   // SD24MEM Overflow
        break;
      case 4:                                   // SD24MEM0 IFG
        break;
      case 6:                                   // SD24MEM1 IFG
        break;
      case 8:                                   // SD24MEM2 IFG
        Ch0results[0] = SD24MEM0;
        Ch0results[1] = SD24MEM0;
        Ch0results[2]=Ch0results[0]<<13;
        Ch0results[3]=Ch0results[1]&&0x003fff;
        Ch0results[4]=Ch0results[0]+Ch0results[1];
        Ch0results[5]=Ch0results[4]>>5;
        
        P1OUT ^=BIT3;
        break;
      }
}

问题4

高阻抗输入缓冲模式怎么用？