求助！！关于51单片机定时器

只看该作者 · 2011-11-10 20:52

#include<reg52.h>
sbit latch1=P2^1;
sbit latch2=P2^2;
void delay(unsigned int t);
unsigned char weima[8]=
{0xfe,0xfd,0xfb,0xf7,0xef,0xdf,0xbf,0x7f};
unsigned char duanma[10]=
{0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f};
unsigned char LED[]={0xcf,0xf3,0xfc,0xf3};
unsigned char tempdata[10];
void delay(unsigned int t);
void display(unsigned char firstbite,unsigned char num);
main(void)
{
unsigned int m=30,n,i=0;
P1=0xcf;
TMOD=0x10;
TH1=0x3c;
  TL1=0xb0;
  TR1=1;
while(1)
{
  if(TF1==1)
{
TF1=0;
n++;
TH1=0x3c;
   TL1=0xb0;
if(n==20)
{
   n=0;
   if(m>0) m--;
   if(m==0)
   {
      i++;
   P1=LED[i];
   if(i==3)i=0;
      m=30;
   }

   }
}
tempdata[0]=duanma[m/10];
tempdata[1]=duanma[m%10];
display(3,2);
}
}
  void delay(unsigned int t)
{
while(t--);
}
void display(unsigned char firstbite,unsigned char num)
{
unsigned int i;
for(i=0;i<num;i++)
{
  P0=0;
  latch2=1;
  latch2=0;
  P0=weima[i+firstbite];
  latch1=1;
  latch1=0;
  P0=tempdata[i];
  latch2=1;
  latch2=0;
   delay(200);
}
}
这个程序的定时不准我本来定的间隔是1s 结果运行时是1.04s左右，通过改初值也无法精确到一秒，总会多或少0.0几秒，请高手给看看是怎么回事？晶振是12MHZ的  谢谢

1万 · 2011-11-10 21:23

我看到一大堆跟定时器不相干的代码，先删干净了再来。

1万 · 2011-11-11 08:07

本帖最后由 ayb_ice 于 2011-11-11 11:04 编辑

//------------
// t0.c

void isr_t0(void) interrupt 1
{
extern void reload_t0(void);

reload_t0();

other()....
}

//------------
// t0.asm
//---------------------------------------
// 系统定时器0初值重装载
//---------------------------------------
// void reload_t0(void);
?PR?reload_t0?SYSTEM SEGMENT CODE
rseg ?PR?reload_t0?SYSTEM
$reguse reload_t0(a,psw)
public  reload_t0
T0_RELOAD EQU    -1250 // 1.25MS*8=10MS
reload_t0:
      setb c
      jbc    ea,$+3+1
      clr    c
      push psw
      CLR    TR0
      MOV    A,TL0
      ADD    A,#LOW (T0_RELOAD + 7)
      MOV    TL0,A
      MOV    A,TH0
      ADDC A,#HIGH (T0_RELOAD + 7)
      MOV    TH0,A
      SETB TR0
      pop    psw
      mov    ea,c
      ret