電子時(shí)鐘

做了個(gè)電子時(shí)鐘，不知為何中斷程序不能計(jì)時(shí)，只顯示開(kāi)機(jī)時(shí)間。請(qǐng)各位高手賜教。。。

程序代碼如下：
 

DISSEC EQU 20H      ;定義秒顯示單元

          DISMIN EQU 21H       ;定義分鐘顯示單元

          DISHOR EQU 22H       ;定義小時(shí)顯示單元

          CLKSEC EQU 23H       ;定義秒走時(shí)單元

          CLKMIN EQU 24H        ;定義分鐘走時(shí)單元

          CLKHOR EQU 25H         ;定義小時(shí)走時(shí)單元

          SECSIG EQU 29H       ;定義一秒鐘到標(biāo)志位

          ORG 000H

          LJMP START

          ORG 000BH

          LJMP INT_B

          ORG 0030H

   START: MOV SP ,#70H    ;堆棧指針賦初值

          MOV SECSIG,#2          ;2*500ms=1s

          MOV TMOD,#01H           ;使用定時(shí)器1定時(shí)500ms

          MOV TH0,#3CH            ;對(duì)定時(shí)器賦初值

          MOV TL0,#0B0H

          SETB EA                  ;開(kāi)總中斷

          SETB ET0                 ;開(kāi)定時(shí)器0中斷

          SETB TR0                 ;啟動(dòng)定時(shí)器0

          CLR A                    ;將開(kāi)機(jī)時(shí)鐘顯示設(shè)置為12:00:00

          MOV CLKSEC,A

          MOV CLKMIN,A

          MOV CLKHOR,#12

DISPLY:                  ;顯示程序

          MOV DISSEC,CLKSEC        ;將走時(shí)單元數(shù)據(jù)傳送到顯示單元

          MOV DISMIN,CLKMIN

          MOV DISHOR,CLKHOR

          MOV A,DISSEC              ;轉(zhuǎn)換顯示程序

          MOV B,#10

          DIV AB

          MOV 42H,B    ;秒位轉(zhuǎn)換

          MOV 43H,A

          MOV A,DISMIN

          MOV B,#10

          DIV AB

          MOV 44H,B    ;分鐘轉(zhuǎn)換

          MOV 45H,A

          MOV A,DISHOR

          MOV B,#10

          DIV AB

          MOV 46H,B      ;小時(shí)轉(zhuǎn)換

          MOV 47H,A

          MOV DPTR,#TABLE

          MOV A,42H        ;秒位顯示

          MOV P2,#0FEH      ;將位選碼送P2

          MOVC A,@A+DPTR

          MOV P0,A

          LCALL DELAY2ms

          MOV A,43H

          MOVC A,@A+DPTR

          MOV P2,#0FDH     ;將位選碼送P2

          MOV P0,A

          LCALL DELAY2ms

          MOV A,44H         ;分鐘顯示

          MOVC A,@A+DPTR

          MOV P2,#0FBH     ;將位選碼送P2

          MOV P0,A

          LCALL DELAY2ms

          MOV A,45H

          MOVC A,@A+DPTR

          MOV P2,#0F7H      ;將位選碼送P2

          MOV P0,A

          LCALL DELAY2ms

          MOV A,46H         ;小時(shí)顯示

          MOVC A,@A+DPTR

          MOV P2,#0EFH     ;將位選碼送P2

          MOV P0,A

          LCALL DELAY2ms

          MOV A,47H

          MOVC A,@A+DPTR

          MOV P2,#0DFH      ;將位選碼送P2

          MOV P0,A

          LCALL DELAY2ms

          LJMP DISPLY

    INT_B:PUSH  PSW          ;中斷程序

          PUSH  ACC          ;入棧保護(hù)現(xiàn)場(chǎng)

          MOV TH0,#3CH          ;對(duì)計(jì)數(shù)器重新賦值

          MOV TL0,#0B0H               

          DJNZ SECSIG,TT    ;判斷 1秒時(shí)間到否，不到轉(zhuǎn)向TT

          MOV SECSIG,#2     ;一秒到時(shí)對(duì)標(biāo)志位重新賦值

          MOV A,CLKSEC      ;對(duì)秒數(shù)據(jù)進(jìn)行加一處理

          ADD A,#1

          CJNE A,#60,TT

          MOV A,#0

          MOV CLKSEC,A

          MOV A,CLKMIN      ;對(duì)分鐘數(shù)據(jù)進(jìn)行加一處理

          ADD A,#1

          CJNE A,#60,TT

          MOV A,#0

          MOV CLKMIN,A

          MOV A,CLKHOR      ;對(duì)小時(shí)數(shù)據(jù)進(jìn)行加以處理

          ADD A,#1

          CJNE A,#24,TT

          MOV A,#0

          MOV CLKHOR,A

       TT:POP ACC           ;TT為恢復(fù)現(xiàn)場(chǎng)中斷返回

          POP PSW

          RETI

 DELAY2ms:MOV 40H,#4   ;2MS延時(shí)程序

          D1:MOV 41H,#248

          DJNZ 41H,$

          DJNZ 40H,D1

          RET

   TABLE: DB 3FH,06H,5BH,4FH,66H,6DH,7DH,07H,7FH,6FH    ;顯示數(shù)碼表0~9

          END