<>51定时器中断
<>1.定时器/计数器
51单片机有2个16位定时器/计数器：定时器0（T0为P3.4） 和定时器1（T1为P3.5）
这里所说的16位是指定时/计数器内部分别有16位的计数寄 存器。当工作在定时模式时，每经过一个机器周期内部的16位计数
寄存器的值就会加1，当这个寄存器装满时溢出。 我们可以算出工作在定时模式时最高单次定时时间为 65535*1.085us=时间（单位us）
当工作在计数器模式时，T0(P3.4引脚),T1（P3.5引脚）每 来一个脉冲计数寄存器加1
定时器作用：定时计数器可以用于精确事件定时，PWM脉宽调 制，波形发生，信号时序测量的方面。
<>使用51定时/计数器步骤：
（1）启动定时/计数器（通过TCON控制器）
（2）设置定时/计数器工作模式（通过TMOD控制器）
（3）查询定时/计数器是否溢出（读TCON内TF位
<>3.代码片：
（1）定时器定时：
#include <reg52.h> #include <intrins.h> #define uint unsigned int #define
uchar unsigned char sbit DU = P2^6; sbit WE = P2^7; uchar code tabel[]= {0x3F,
0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D, 0x07, 0x7F, 0x6F,}; void delay(uint z) {
uint x,y; for(x = z; x > 0; x--) for(y = 114; y > 0 ; y--); } void
display(uchar i) { uchar bai, shi, ge; bai = i / 100; //236 / 100 = 2 shi =
i % 100 / 10; //236 % 100 / 10 = 3 ge = i % 10;//236 % 10 =6 P0 = 0XFF;
WE = 1; P0 = 0XFE; //1111 1110 WE = 0; DU = 1; P0 = tabel[bai];// DU =
0; delay(5); P0 = 0XFF; WE = 1; P0 = 0XFD; //1111 1101 WE = 0; DU = 1;
P0 = tabel[shi];// DU = 0; delay(5); P0 = 0XFF; WE = 1; P0 = 0XFB; //1111
1011 WE = 0; DU = 1; P0 = tabel[ge];// DU = 0; delay(5); } void
timer0Init() { TR0 = 1; TMOD = 0X01; TH0 = 0x4b; TL0 = 0xfd; } void main()
{ uchar mSec, Sec; timer0Init(); while(1) { if(TF0 == 1) { TF0 = 0;
TH0 = 0x4b; TL0 = 0xfd; mSec++; if(mSec == 20) { mSec = 0;
Sec++; } } display(Sec); if(Sec > 10) Sec = 0; } }
（2）定时器计数：
#include <reg52.h> #include <intrins.h> #define uint unsigned int #define
uchar unsigned char sbit DU = P2^6; sbit WE = P2^7; sbit LED1 = P1^0; uchar
code tabel[]= {0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D, 0x07, 0x7F, 0x6F,};
void delay(uint z) { uint x,y; for(x = z; x > 0; x--) for(y = 114; y > 0 ;
y--); } void display(uchar i) { uchar bai, shi, ge; bai = i / 100; shi = i %
100 / 10; ge = i % 10; P0 = 0XFF; WE = 1; P0 = 0XFE; //1111 1110 WE = 0; DU =
1; P0 = tabel[bai];// DU = 0; delay(5); P0 = 0XFF; WE = 1; P0 = 0XFD; WE = 0;
DU = 1; P0 = tabel[shi]; DU = 0; delay(5); P0 = 0XFF; WE = 1; P0 = 0XFB; //1111
1011 WE = 0; DU = 1; P0 = tabel[ge];// DU = 0; delay(5); } void timer0Init() {
TR0 = 1; TMOD |= 0X05; TH0 = 0; TL0 = 0; } void timer1Init() { TR1 = 1; TMOD |=
0X10; TH1 = 0x4b; TL1 = 0xfd; } void main() { uchar mSec, Sec; timer0Init();
timer1Init(); while(1) { if(TF1 == 1) { TF1 = 0; TH1 = 0x4b; TL1 = 0xfd;
mSec++; if(mSec == 10) { mSec = 0; LED1 = ~LED1; } } display(TL0); } }
（3）定时器中断：
#include <reg52.h> #include <intrins.h> #define uint unsigned int #define
uchar unsigned char sbit DU = P2^6; sbit WE = P2^7; sbit key_s2 = P3^0; sbit
key_s3 = P3^1; uchar num; uchar mSec, Sec; uchar code SMGduan[]= {0x3F, 0x06,
0x5B, 0x4F, 0x66, 0x6D, 0x7D, 0x07, 0x7F, 0x6F,}; uchar code SMGwei[] = {0xfe,
0xfd, 0xfb}; void delay(uint z) { uint x,y; for(x = z; x > 0; x--) for(y = 114;
y > 0 ; y--); } void display(uchar i) { static uchar wei; P0 = 0XFF; WE = 1; P0
= SMGwei[wei]; WE = 0; switch(wei) { case 0: DU = 1; P0 = SMGduan[i / 100]; DU
= 0; break; case 1: DU = 1; P0 = SMGduan[i % 100 / 10]; DU = 0; break; case 2:
DU = 1; P0 = SMGduan[i % 10]; DU = 0; break; } wei++; if(wei == 3) wei = 0; }
void timer0Init() { EA = 1; ET0 = 1; TR0 = 1; TMOD = 0X01; TH0 = 0xED; TL0 =
0xFF; } void main() { timer0Init(); while(1) { if(key_s2 == 0) { delay(20);
if(key_s2 == 0) { if(num != 120) num++; while(!key_s2); } } if(key_s3 == 0) {
delay(20); if(key_s3 == 0) { if(num > 0) num--; while(!key_s3); } } } } void
timer0() interrupt 1 { TH0 = 0xED; TL0 = 0xFF; display(num); }
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