按键和定时器中断综合应用-秒表计时器

& INT1按键中断INT0#
和T0中断的综合应用
‐简易秒表计时器
范例1：汇编源代码
范例2：C51源代码
P7 EQU 0F8H ORG 0100H
#60H P6 EQU 0E8H
D1 EQU 0FEH //数码管个位EQU 0FDH MAIN: MOV SP ,#60H //设置堆栈
MOV P2,#0FFH //关P2口LED MOV TMOD,#00H D2 //十位D3 EQU 0FBH // 百位
VARX DATA 30H //计数变量DATA 31H MOV TH0,#4BH
MOV TL0,#0FDH //设置T0MOV R7,#20MOV VARX,#0 //置计数变量0DIG1 //BCD 个位DIG2 DATA 32H //BCD 十位DIG3 DATA 33H //BCD ,SETB ET0SETB EX0SETB IT0//百位ORG 0000H LJMP MAIN SETB EX1SETB IT1
SETB EA //允许相关中断
ORG 0003H
LJMP KY1INT //KY1中断ORG 000BH
LJMP T0INT //T0中断ORG 0013H
KY2INT //KY2LJMP 中断
CONV:
MOV A,VARX //读计数变量MOV A,DIG2 //读十位BCD MOV B,#100DIV AB DIG3A MOVC A,@A+DPTR MOV P7,A P6#D2//MOV DIG3,A MOV A,B MOV B,#10MOV P6,#D2 查表送显示ACALL DELAY //扫描延时A,DIG3//DIV AB
MOV DIG2,A DIG1B MOV 读百位BCD MOVC A,@A+DPTR MOV P7,A
MOV DIG1,B //转换为3位BCD DISP: MOV A,DIG1 //读个位BCD
MOV DPTR,#SEGTBL MOV P6,#D3 //查表送显示ACALL DELAY
CONV //MOVC A,@A+DPTR MOV P7,A
P6,#D1//LJMP 返回读取VARX
MOV 查表送显示
ACALL DELAY //扫描延时
•//软件延时程序段•R1#100T0INT: DJNZ R7,BACK
R7#20DELAY: MOV R1,#100•DL1: MOV R2,#10R2DL2
MOV R7,#20CPL P2.0INC VARX •DL2: DJNZ R2,DL2•DJNZ R1,DL1BACK: RETI
//•RET
KY1INT:
共阳型数码管字符//0‐9的的段码表
ORG 0200H
0C0H 0F9H 0A4H 0B0H
JNB TR0,RUNT0 //若未启动TR0,则启动计数
SEGTBL: DB 0C0H,0F9H,0A4H,0B0H DB 99H,92H,82H,0F8H,80H,90H
CLR TR0 //否则停止计数RETI
RUNT0: SETB TR0
RETI
KY2INT: MOV VARX,#0 //将VARX 清零
RETI
范例2：C51的程序实现
•#include "stc15.h"
•#include intrins.h
"intrins h"
•typedef unsigned char u8;
•u8 varx;;
•#define D1 0xFE
•#define D2 0xFD
•#define D3 0xFB
•u8 dig1,dig2,dig3;
•u8 count;
8t
•void dly20ms();
•const u8 code Seg8[10] =
{0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};•u8 *ptr;
•void main()
•{
•P2 = 0xFF;•varx= 0;
•ptr= Seg8;•count = 20;•TMOD = 0x00;
TH0 19453/256;•=
•TL0 = 19453%256;•ET0 = 1;;
•EX0 = 1;
•IT0 = 1;;
•EX1 = 1;
•IT1 = 1;
•EA = 1;
•while(1)
•{
•dig3 = varx/100;•dig2 = (varx%100)/10;•dig1 = (varx%100)%10;•P7 = *(ptr+dig1);
•P6 = D1;
•dly20ms();
•P7 = *(ptr+dig2);
•P6 = D2;
•dly20ms();
•=*(ptr+dig3);
P7 (ptr dig3);
•P6 = D3;
•dly20ms();
•}
•
•}
•void ky1int() interrupt 0•{
•if(TR0 == 0 ) TR0 = 1;•else TR0 =0;
•}
•void ky2int() interrupt 2•0;}
{ varx=
•void T0int() interrupt 1•{
()
•if(count‐‐!=0) return;•else
•{
•P20 ^= 1;
•count = 20;•varx++;
•}
•}
•void dly20ms()
•{ int i;
•i= 2000;;
•while(i‐‐!=0) _nop_();
•}
如果不了解单片机内部存储器结构和硬件知识，缺如果不了解单片机内部存储器结构和硬件知识缺乏对程序执行流程和中断原理的理解，想完整编写这样一段C程序实现秒表计时器功能，也并不容易。

程序实现秒表计时器功能也并不容易这就是为什么一开始要花些时间和力气深入学习单片机内部硬件原理的原因。

片机内部硬件原理的原因。