单片机定时1s慢了许多请大神帮忙

1987的一个人 · 发表于 2012-9-8 16:34:55

#include<reg52.h>
#include<ye12864.h>
unsigned char t,flag = 2;
void Time_Count0_Init()    //定时器初始化函数
{
TMOD = 0X01;  //设置定时器工作方式为1
TH0 = 0X4C;    //定时50ms
TL0 = 0X00;
PCON=0X80; //波特率倍频
TR0 = 1;
ET0 = 1;
EA = 1;
}
void xs(uint dd,i,k)  //结果显示函数，dd 要显示的函数，k显示的列数位置，i显示行数位置
{
uint temp4,temp5,shu[20];
char j = 0;
if(dd<10)
{
   w_shuzi(k,i,0);
w_shuzi(k+1,i,dd);
}
else
{
      while(dd)
   {
temp4 = dd/10;
temp5 = dd%10;
shu[j++] = temp5;
dd = temp4;
   }
   for(--j;j>=0;j--)
   {
w_shuzi(k++,i,shu[j]);
   }
}
}
void calendar()    //万年历函数
{
unsigned char yue,ri,shi,fen,miao,temp,i,xq;
unsigned char dyue[] = {1,3,5,7,8,10,12},xyue[4] = {4,6,9,11};
unsigned int nian;
if(flag ==2)
{
nian = 2012;
yue = 12;
ri = 30;
shi = 22;
fen = 58;
miao = 50;
}
if(flag == 1)
{
miao++;
if(yue == 12&&ri == 31&&shi == 23&&fen == 59&&miao == 60)
{
yue = 1;
ri = 1;
shi = 0;
fen = 0;
miao = 0;
xq++;
}
if(miao == 60)
{
fen++;
miao = 0;
}
if(fen == 60)
{
shi++;
fen = 0;
}
if(shi == 24)
{
shi = 0;
ri++;
xq++;
if(xq == 7)
xq = 0;
}
if(ri == 28&&ri == 29&&ri == 30&&ri == 31)    //当日期为28，29，30，30,31才判断月份是否加一
{
for(i = 0;i<7;i++)
{
if(yue == dyue[i])
temp = 2;
}
for(i = 0;i<4;i++)
{
if(yue == xyue[i])
temp = 1;
else
temp = 0;
}
}
if(temp == 2)    //是大月
if(ri == 31)
yue++;
if(temp == 1)    //是小月
if(ri == 30)
yue++;
if(temp == 0)    //2月
if (nian%400 == 0 || (nian%4 == 0 && nian%100 != 0))  //是闰年
{
if(ri == 29)
yue++;
}
else if(ri == 28)
        yue++;
xs(nian,2,0);
xs(yue,2,6);
xs(ri,2,9);
xs(shi,4,0);
xs(fen,4,3);
xs(miao,4,6);
w_hanzi(8,2,xq+5);
flag = 0;
}
}
void main()
{
   LCD_init();
   LCD_qingpin(0x00);
   delay(10);
   Time_Count0_Init(); //定时器初始化
   w_hanzi(0,0,0); //显示万年历
   w_hanzi(1,0,1);
   w_hanzi(2,0,2);
   w_hanzi(6,2,3);
   w_hanzi(7,2,4);
   while(1)
   {
   calendar();
   }
}
void time_count0() interrupt 1
{
TF0 = 0;
TH0 = 0X4C;    //定时50ms
TL0 = 0X00;
TR0 = 0;
if(t == 20)
{
t = 0;
flag = 1;
}
t++;
TR0 = 1;
}

zhikunWang · 发表于 2012-9-8 16:48:46

不知道楼主是不是用的是STC单片机，精密一点要使用外部晶振！

lcw_swust · 发表于 2012-9-8 17:23:20

应当用自动重装模式
若在中断中重装，这个中断的响应的时刻是不确定的，而且从中断响应到进入中断函数是需要时间的

zhuxm · 发表于 2012-9-8 19:09:49

void time_count0() interrupt 1
{
      TR0 = 0;
      TF0 = 0;
      TH0 = 0X4C;       //定时50ms
      TL0 = 0X00;
      TR0 = 1;
      if(t == 20)
      {
            t = 0;
            flag = 1;
      }
      t++;
}
试试看，进一步可以TL0=0x09(可调整)，Keil仿真一下。

jetli · 发表于 2012-9-8 19:38:10

拿示波器，卡一下时间，，，慢慢调整，

1987的一个人 · 发表于 2012-9-9 08:50:57

是用STC单片机晶振是11.0592Mhz

1987的一个人 · 发表于 2012-9-9 08:58:05

谢谢各位！的确把t++放在if前面就可以了，不过是什么原因还是不明白！

chengzepeng · 发表于 2012-9-9 15:42:30

本帖最后由 chengzepeng 于 2012-9-9 16:06 编辑

void time_count0() interrupt 1
{
// TF0 = 0; // 进入中断会自动清，不需要额外加
TH0 = 0X4c; // 定时50ms
--TL0; // 减去定时器填充的时间
// TR0 = 0; // 不要关定时器，否则误差更大
++t; // 把t放在+后面计算更快
if(t == 20)
{
t = 0;
flag = 1;
}
// TR0 = 1;
}

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fangmcu · 发表于 2012-9-9 15:46:20

做时钟，建议用自动重装模式即模式2！！

1987的一个人 · 发表于 2012-9-9 17:23:47

好的谢谢各位

millwood0 · 发表于 2012-9-9 18:58:01

i will give you something much simpler and much more accurate, yet without using an auto-reload timer.

#define F_XTAL 11059200ul //crystal frequency, in Mhz
#define TMR1s (F_XTAL / 12) //1st count, in ticks
#define TMR500ms (TMR1s / 2) //500ms delay
#define TMR100ms (TMR1s / 10) //100ms delay
#define TMR_PR TMR1s //tmr period
unsigned long tmr_cnt = 0; //tmr counter
...
//when you initialize the timer, clear TH0/TL0
//isr
void time_count0() interrupt 1
{
tmr_cnt += 0x10000ul; //increment tmr counter
if(tmr_cnt >= TMR_PR) //desired time has elapsed
{
tmr_cnt -= TMR_PR; //update timer counter
flag = 1;
}
}

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F_XTAL defines the crystal you are using. If you change crystal in the future, you just need to update the figure here and recompile.
TMR1s defines how many ticks for 1 second, assuming a 12-cycle mcu. if you use a 1-cycle mcu, replace that 12 with 1
TMR500ms / TMR100ms are some pre-define cycle counts, and you can add your own.
TMR_PR is the desired timer period. here we set it to 1 second. If you use TMR500ms instead of TMR1s here, the clock will set flag every 500ms.

in the isr, we increment tmr_cnt. 0x10000ul for a 16bit timer. if you were to use an 8-bit timer, use 0x100 instead.

no auto reloading. the timer will be as accurate as your crystal, particularly in long-term applications. you can also introduce trimming here to get the timer incredibly accurate.

It is called the Black Roman approach.

单片机定时1s慢了许多 请大神帮忙

阿莫论坛20周年了！感谢大家的支持与爱护！！

单片机定时1s慢了许多请大神帮忙