精確延時計算公式:

延時時間=[(2*第一層循環+3)*第二層循環+3]*第三層循環+5



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;延時5秒左右
DELAY5S:PUSH   04H                 
        PUSH   05H             
        PUSH   06H                 
        MOV    R4,#50              
DELAY5S_0:MOV R5,#200                               
DELAY5S_1:MOV R6,#245                               
        DJNZ   R6,$                          
        DJNZ   R5,DELAY5S_1
        DJNZ   R4,DELAY5S_0                          
        POP    06H                   
        POP    05H                   
        POP    04H                   
        RET                                          



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;513微秒延時程序
DELAY: MOV     R2,#0FEH
DELAY1: DJNZ    R2,DELAY1
RET 



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;10毫秒延時程序
DL10MS: MOV     R3,#14H
DL10MS1:LCALL   DELAY
        DJNZ    R3,DL10MS1
        RET



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;0.1s延時程序12mhz
DELAY: MOV R6,#250
DL1: MOV R7,#200
DL2: DJNZ R6,DL2
DJNZ R7,DL1
RET



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;延時1046549微秒(12mhz)
;具體的計算公式是:
;((((r7*2+1)+2)*r6+1)+2)*r5+1+4 = ((r7*2+3)*r6+3)

*r5+5
DEL : MOV R5,#08H
DEL1: MOV R6,#0FFH
DEL2: MOV R7,#0FFH
        DJNZ R7,$
        DJNZ R6,DEL2
        DJNZ R5,DEL1
        RET



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;1秒延時子程序是以12MHz晶振
Delay1S:mov r1,#50
del0: mov r2,#91 
del1:   mov r3,#100 
        djnz r3,$ 
        djnz r2,del1 
        djnz r1,del0
   Ret



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;1秒延時子程序是以12MHz晶振為例算指令周期耗時
KK: MOV    R5,#10    ;1指令周期1
K1: MOV    R6,#0FFH    ;1指令周期10
K2: MOV    R7,#80H    ;1指令周期256*10=2560
K3: NOP         ;1指令周期

128*256*10=327680
DJNZ    R7,K3    ;2指令周期

2*128*256*10=655360
DJNZ    R6,K2    ;2指令周期

2*256*10=5120
DJNZ    R5,K1    ;2指令周期2*10=20
RET       
;2指令周期21+10+2560+327680+655360+5120+20+2=990753
;約等于1秒1秒=1000000微秒



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;這個算下來也只有0.998抄
T_0: MOV   R7,#10;
D1: MOV   R6,#200;
D2: MOV   R5,#248;
DJNZ   R5,$
DJNZ   R6,D2;
DJNZ   R7,D1;
RET 



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;這樣算下來應該是1.000011秒
T_0: MOV   R7,#10;
D1: MOV   R6,#200;
D2: NOP
MOV   R5,#248;
DJNZ   R5,$
DJNZ   R6,D2;
DJNZ   R7,D1;
RET



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DELAY_2S:   ;10MS(11.0592mhz)
MOV R3,#200
JMP DELAY10MS
DELAY_100MS:    ;100MS(11.0592mhz)
MOV R3,#10
JMP DELAY10MS
DELAY_10MS: 
MOV R3,#1
DELAY10MS:    ;去抖動10MS



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(11.0592mhz)
MOV R4,#20
DELAY10MSA:
MOV R5,#247
DJNZ R5,$
DJNZ R4,DELAY10MSA
DJNZ R3,DELAY10MS
RET



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DELAY_500MS:                    ;500500MS
MOV R2,#208
JMP DELAY_MS
DELAY_175MS:   ;175MS
MOV R2,#73
JMP DELAY_MS
delaY_120MS:   ;120MS
MOV R2,#50
JMP DELAY_MS
delay_60ms:   ;60ms
MOV R2,#25
JMP DELAY_MS
delay_30ms:   ;30ms
MOV R2,#12
JMP DELAY_MS
DELAY_5MS:   ;5MS
MOV R2,#2
;===================================
DELAY_MS:
CALL DELAY2400
DJNZ R2,DELAY_MS
RET
;===================================
DELAY2400:   ;10x244+4=2447 

/1.024=2390
MOV R0,#244 ;1
DELAY24001:
MUL AB ;4
MUL AB ;4
DJNZ R0,DELAY24001 ;2
RET



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DELAY: ;延時子程序(1秒)
MOV R0,#0AH
DELAY1: MOV R1,#00H
DELAY2: MOV R2,#0B2H
DJNZ R2,$
DJNZ R1,DELAY2
DJNZ R0,DELAY1
RET


MOV R2,#10 ;延時1秒
LCALL DELAY
MOV R2,#50 ;延時5秒
LCALL DELAY
DELAY: ;延時子程序
PUSH R2
PUSH R1
PUSH R0
DELAY1: MOV R1,#00H
DELAY2: MOV R0,#0B2H
DJNZ R0,$
DJNZ R1,DELAY2 ;延時 100 mS
DJNZ R2,DELAY1
POP R0
POP R1
POP R2
RET



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1:DEL:   MOV   R7,   #200 

           DEL1:   MOV   R6,   #123

                        NOP

           DEL2:   DJNZ   R6,   DEL2

                        DJNZ   R7,   DEL1

                        RET

是50.001ms 算法是:
0.001ms+200*0.001ms+200*0.001ms+200*123*0.002ms+200*0.002ms

;(123*2+4)*200+1



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2: DEL: MOV R7, #200

DEL1: MOV R6, #123

DEL2:NOP

      DJNZ R6,DEL2

      DJNZ R7,DEL1

RET



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D500MS: 
PUSH PSW
SETB RS0
MOV R7,#200
D51: MOV R6,#250
D52: NOP
NOP
NOP
NOP
DJNZ R6,D52
DJNZ R7,D51
POP PSW
RET



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DELAY: ;延時1毫秒
PUSH PSW
SETB RS0
MOV R7,#50
D1: MOV R6,#10
D2: DJNZ R6,$
DJNZ R7,D1
POP PSW
RET 



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ORG   0
        LJMP    MAIN
            ORG    000BH
        LJMP    CTC0
   MAIN: MOV   SP, #50H
          CLR   EA
          MOV   TMOD, #01H
          MOV    TH0,#3CH
          MOV    TL0,#0B0H
          MOV    R4, #10
           SETB   ET0
           SETB   EA
           SETB   TR0
            SJMP $ ; 
   CTC0:   MOV TH0, #3CH
           MOV TL0, #0B0H
           DJNZ R4, LP
           CPL   P1.0
           MOV   R4, #10
     LP:    RETI
          END