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问 各位大侠：
    我是新手，请多关照！我想用下面的程序测量ICP引脚上的周期，可是好象总存在问题，请高手帮我看看问题出在什么地方？谢谢，比较急！
    #include<iom8v.h>
#include<math.h>
#include <macros.h>
#define osccal 0xae//内部RC校正常数
#pragma data:code
const unsigned char table[16]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,
                               0x90,0x88,0x83,0xc6,0xa1,0x86,0x8e};

#pragma data:data
unsigned char ledbuff[]={0,0,0,0};
unsigned int oldcount;
unsigned int newcount;
unsigned char counter;
/*                微秒级延时程序              */
void delay_us(int time)
     {     
        do
          {
         time--;
        }    
        while (time>1);
     }      
//动态扫描显示,使用B口传递显示数据

void display(void)
{
  unsigned char i;
  DDRB|=0xfe;
  PORTB|=0xfe;
  DDRD|=0xf0;
  PORTD|=0xf0;  
  for(i=0;i<4;i++)
           {    
          PORTB=ledbuff[i];
          PORTD&=~(1<<(i+4));
          delay_us(400);
          PORTD|=0xf0;
         }
}

//将COUNT 十六进制数据转换为LED 七段码

void hextobcd(unsigned int count)
{
unsigned char i;
for(i=0;i<4;i++)
    {
     ledbuff[i]=table[count%10];
     count=count/10;  
    }
}

//初始化

void sys_init(void)
{
DDRB|=0xfe;            //PB0不能作为输出，否则会引发中断
PORTB|=0xfe;           //端口初始化
DDRD|=0xf0;
PORTD|=0xf0;          //片选，低有效
TIMSK=0x20;           //使能T1捕捉中断
TCCR1A=0x00;
TCCR1B=0xC2;          //CK/8，捕捉周期的单位为1us
ICR1=0;               
TCNT1=0;
counter=0;
}
//捕捉中断处理程序
#pragma interrupt_handler ICP_timer1:iv_TIMER1_CAPT
void ICP_timer1(void)     
{
unsigned int temp;
counter++;
if(counter==2)
    {
     newcount=ICR1-temp;
     counter=0;
     ICR1=0;
     temp=0;     
     }
//TCCR1B=0xC2;
temp=ICR1;
TCNT1=0;
}
//测量ICP引脚上的信号的周期
void main()
{ void sys_init(void);

OSCCAL=osccal;                //校正振荡频率
sys_init();
SEI();                        //使能全局中断
while(1)
    {
     if ((newcount&0xfff8)!=(oldcount&0xfff8))
        {
         oldcount=newcount;
        }
     hextobcd(oldcount);
     display();
    }
}
//周期我用示波器测过，很稳定的，可是测量显示值总在跳，是设置的问题吗？还是别的地方出了问题？
答 1: 使用外部振荡试试，内部rc有误差

感谢分享