ADC，32次转换后，数码管就不显示了，是什么问题呀？

/*******************************************ADC转换通道口为P1.1 本程模拟量大于0.5*AVCC时P1.6灯亮 小于0.5*AVCC时P1.0灯亮数码管显示AD转换结果（非真实电压，未加算法处理）********************************************//********************************************本程序实现数码管四位动态显示如：8.29#define AB P2^0#define CLK P2^1#define COM1 P2^2#define COM2 P2^3#define COM3 P2^4#define COM4 P2^5***********************************************/#include "msp430g2553.h"unsigned int results[32];unsigned int average;unsigned char led[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};//09数字代码unsigned int x1,x2,x3,x4;//个十百千/*******************74ls164*************************/void sent(unsigned char nu)//74ls164是8位串入并出移位寄存器。发送数据到数码管{unsigned char a;for(a=0;a<8;a++){if((nu&0x01)==0){P2OUT&=(BIT0);}else{P2OUT|=BIT0;}P2OUT&=(BIT1); //P2OUT|=BIT1; //上升沿nu=nu>>1;}}/*******************取出要显示的数字的给位数字值*************************/void geishu(int x){x1=x%10;//个位x=x/10;x2=x%10;//十位x=x/10;x3=x%10;//百位x=x/10;x4=x%10;//千位}/*******************在数码管上一次显示各位*************************/void display(void){sent(led[x1]);//4P2OUT&=(BIT5);P2OUT|=(BIT2+BIT3+BIT4);__delay_cycles(5000);sent(led[(x2)]);//3P2OUT&=(BIT4);P2OUT|=(BIT2+BIT3+BIT5);__delay_cycles(5000);sent(led[x3]|0x80);//2 并且让该位小数点常亮P2OUT&=(BIT3);P2OUT|=(BIT2+BIT4+BIT5);__delay_cycles(5000);sent(led[x4]);//1P2OUT&=(BIT2);P2OUT|=(BIT3+BIT4+BIT5);__delay_cycles(5000);}void main(void){int xx;WDTCTL = WDTPW + WDTHOLD; // Stop WDTADC10CTL0|=ADC10ON+ADC10IE+REFON+REF2_5V+SREF_1+MSC+ADC10SHT_2;ADC10CTL1 = INCH_1; // input A1ADC10AE0 |= 0x02; // PA.1 ADC option selectP1DIR |= BIT6+BIT0; // Set P1.0 to output directionP1OUT&=(BIT6+BIT0);P2DIR|=(BIT2+BIT3+BIT4+BIT5); // 打开1,并赋初值。P2OUT|=(BIT2+BIT3+BIT4+BIT5);P2DIR|=(BIT0+BIT1); // AB和CLOCK设置为输入。P2OUT&=(BIT0+BIT1);for (;;){ADC10CTL0 |= ENC + ADC10SC; // Sampling and conversion start__bis_SR_register(CPUOFF + GIE); // LPM0, ADC10_ISR will force exitif (ADC10MEM < 0x1FF){ P1OUT |= BIT0; P1OUT &= BIT6; } // Clear P1.0 LED offelse{ P1OUT |= BIT6; P1OUT &= BIT0; } // Set P1.0 LED on// average=ADC10MEM;xx=average;geishu(xx);display();}}// ADC10 interrupt service routine#pragma vector=ADC10_VECTOR__interrupt void ADC10_ISR(void){static unsigned int index = 0;results[index++] = ADC10MEM; // Move results, IFG is clearedif(index == 31){unsigned int i;average = 0;for(i = 0; i < 32; i++)average += results;average >>= 5; //除以32求平均值index = 0;__bic_SR_register_on_exit(CPUOFF); // Clear CPUOFF bit from 0(SR)}}

static unsigned int index = 0; 这句别放在中断里。