五一電子閱讀：《學單片機》—《20．數字鐘﹝★﹞ 》

1． 實驗任務

（1．開機時，顯示12：00：00的時間開始計時；

（2． P0.0/AD0控制“秒”的調整，每按一次加1秒；

（3． P0.1/AD1控制“分”的調整，每按一次加1分；

（4． P0.2/AD2控制“時”的調整，每按一次加1個小時；

2． 電路原理圖

圖4.20.1

3． 系統板上硬件連線

（1．把“單片機系統”區域中的P1.0－P1.7端口用8芯排線連接到“動態數碼顯示”區域中的A－H端口上；

（2．把“單片機系統：區域中的P3.0－P3.7端口用8芯排線連接到“動態數碼顯示”區域中的S1－S8端口上；

（3．把“單片機系統”區域中的P0.0/AD0、P0.1/AD1、P0.2/AD2端口分別用導線連接到“獨立式鍵盤”區域中的SP3、SP2、SP1端口上；

4． 相關基本知識

（1．動態數碼顯示的方法

（2．獨立式按鍵識別過程

（3． “時”，“分”，“秒”數據送出顯示處理方法

5． 程序框圖

6． 匯編源程序

SECOND EQU 30H

MINITE EQU 31H

HOUR EQU 32H

HOURK BIT P0.0

MINITEK BIT P0.1

SECONDK BIT P0.2

DISPBUF EQU 40H

DISPBIT EQU 48H

T2SCNTA EQU 49H

T2SCNTB EQU 4AH

TEMP EQU 4BH

ORG 00H

LJMP START

ORG 0BH

LJMP INT_T0

START: MOV SECOND,#00H

MOV MINITE,#00H

MOV HOUR,#12

MOV DISPBIT,#00H

MOV T2SCNTA,#00H

MOV T2SCNTB,#00H

MOV TEMP,#0FEH

LCALL DISP

MOV TMOD,#01H

MOV TH0,#(65536-2000) / 256

MOV TL0,#(65536-2000) MOD 256

SETB TR0

SETB ET0

SETB EA

WT: JB SECONDK,NK1

LCALL DELY10MS

JB SECONDK,NK1

INC SECOND

MOV A,SECOND

CJNE A,#60,NS60

MOV SECOND,#00H

NS60: LCALL DISP

JNB SECONDK,$

NK1: JB MINITEK,NK2

LCALL DELY10MS

JB MINITEK,NK2

INC MINITE

MOV A,MINITE

CJNE A,#60,NM60

MOV MINITE,#00H

NM60: LCALL DISP

JNB MINITEK,$

NK2: JB HOURK,NK3

LCALL DELY10MS

JB HOURK,NK3

INC HOUR

MOV A,HOUR

CJNE A,#24,NH24

MOV HOUR,#00H

NH24: LCALL DISP

JNB HOURK,$

NK3: LJMP WT

DELY10MS:

MOV R6,#10

D1: MOV R7,#248

DJNZ R7,$

DJNZ R6,D1

RET

DISP:

MOV A,#DISPBUF

ADD A,#8

DEC A

MOV R1,A

MOV A,HOUR

MOV B,#10

DIV AB

MOV @R1,A

DEC R1

MOV A,B

MOV @R1,A

DEC R1

MOV A,#10

MOV@R1,A

DEC R1

MOV A,MINITE

MOV B,#10

DIV AB

MOV @R1,A

DEC R1

MOV A,B

MOV @R1,A

DEC R1

MOV A,#10

MOV@R1,A

DEC R1

MOV A,SECOND

MOV B,#10

DIV AB

MOV @R1,A

DEC R1

MOV A,B

MOV @R1,A

DEC R1

RET

INT_T0:

MOV TH0,#(65536-2000) / 256

MOV TL0,#(65536-2000) MOD 256

MOV A,#DISPBUF

ADD A,DISPBIT

MOV R0,A

MOV A,@R0

MOV DPTR,#TABLE

MOVC A,@A+DPTR

MOV P1,A

MOV A,DISPBIT

MOV DPTR,#TAB

MOVC A,@A+DPTR

MOV P3,A

INC DISPBIT

MOV A,DISPBIT

CJNE A,#08H,KNA

MOV DISPBIT,#00H

KNA: INC T2SCNTA

MOV A,T2SCNTA

CJNE A,#100,DONE

MOV T2SCNTA,#00H

INC T2SCNTB

MOV A,T2SCNTB

CJNE A,#05H,DONE

MOV T2SCNTB,#00H

INC SECOND

MOV A,SECOND

CJNE A,#60,NEXT

MOV SECOND,#00H

INC MINITE

MOV A,MINITE

CJNE A,#60,NEXT

MOV MINITE,#00H

INC HOUR

MOV A,HOUR

CJNE A,#24,NEXT

MOV HOUR,#00H

NEXT: LCALL DISP

DONE: RETI

TABLE: DB 3FH,06H,5BH,4FH,66H,6DH,7DH,07H,7FH,6FH,40H

TAB: DB 0FEH,0FDH,0FBH,0F7H,0EFH,0DFH,0BFH,07FH

END

7． C語言源程序

#include <AT89X51.H>

unsigned char code dispcode[]={0x3f,0x06,0x5b,0x4f,

0x66,0x6d,0x7d,0x07,

0x7f,0x6f,0x77,0x7c,

0x39,0x5e,0x79,0x71,0x00};

unsigned char dispbitcode[]={0xfe,0xfd,0xfb,0xf7,

0xef,0xdf,0xbf,0x7f};

unsigned char dispbuf[8]={0,0,16,0,0,16,0,0};

unsigned char dispbitcnt;

unsigned char second;

unsigned char minite;

unsigned char hour;

unsigned int tcnt;

unsigned char mstcnt;

unsigned char i,j;

void main(void)

{

TMOD=0x02;

TH0=0x06;

TL0=0x06;

TR0=1;

ET0=1;

EA=1;

while(1)

{

if(P0_0==0)

{

for(i=5;i>0;i--)

for(j=248;j>0;j--);

if(P0_0==0)

{

second++;

if(second==60)

{

second=0;

}

dispbuf[0]=second%10;

dispbuf[1]=second/10;

while(P0_0==0);

}

if(P0_1==0)

{

for(i=5;i>0;i--)

for(j=248;j>0;j--);

if(P0_1==0)

{

minite++;

if(minite==60)

{

minite=0;

}

dispbuf[3]=minite%10;

dispbuf[4]=minite/10;

while(P0_1==0);

}

if(P0_2==0)

{

for(i=5;i>0;i--)

for(j=248;j>0;j--);

if(P0_2==0)

{

hour++;

if(hour==24)

{

hour=0;

}

dispbuf[6]=hour%10;

dispbuf[7]=hour/10;

while(P0_2==0);

}

void t0(void) interrupt 1 using 0

{

mstcnt++;

if(mstcnt==8)

{

mstcnt=0;

P1=dispcode[dispbuf[dispbitcnt]];

P3=dispbitcode[dispbitcnt];

dispbitcnt++;

if(dispbitcnt==8)

{

dispbitcnt=0;

}

tcnt++;

if(tcnt==4000)

{

tcnt=0;

second++;

if(second==60)

{

second=0;

minite++;

if(minite==60)

{

minite=0;

hour++;

if(hour==24)

{

hour=0;

}

dispbuf[0]=second%10;

dispbuf[1]=second/10;

dispbuf[3]=minite%10;

dispbuf[4]=minite/10;

dispbuf[6]=hour%10;

dispbuf[7]=hour/10;

}