60分钟倒计时秒表功能:1.带有启动键Start,暂停键Pause,停止键Stop,复位键Reset;2.4位数码管显示分(两位)秒(两位);3.按启动键启动从60分开始倒计时,按暂停键暂停,显示保持原来计时时间,再次按启动键继续计时,按停止键停止计时,复位键复位,到零停止计时.4.按停止键后,可按中间的4个键,分别对应分的十位(2键),个位(4键),和秒的十位(5键),个位(9键),按动一下,相应的位增1,并保证时间的正确值,再按一次停止键,保存设置值,按其它键则放弃设置时间值,恢复原来的时间.电路图:计时器工作模式:编码(54H单元) 当前工作模式00H Reset01H Start02H Pause03H Stop主程序流程:主程序代码段：ORG 0000HLJMP MAINORG 000BHLJMP TIMER0ORG 1000HMAIN: ACALL INIT ;初始化定时器SETB EA ;开总中断SETB ET0 ;开定时器0中断MOV A, #03H ;设置8155的工作模式, PA, PB输出, PC输入.MOV DPTR, #7F00HMOVX @DPTR, ABEGIN: ACALL DISACALL CLEARACALL CCSCANJNZ INK1AJMP BEGININK1: ACALL DISACALL CLEARACALL CCSCANJNZ INK2AJMP BEGININK2: MOV R2, #7FH ;从最左边列开始扫描MOV R4, #00HCOLUM: MOV DPTR, #7F02HMOV A, R2MOVX @DPTR, AINC DPTRMOVX A, @DPTRJB ACC.2, LONEMOV A, #00HAJMP KCODELONE: JB ACC.1, NEXTMOV A, #04HKCODE: ADD A, R4ACALL PUTBUFKON: ACALL DISACALL CLEARACALL CCSCANJNZ KONNEXT: INC R4MOV A, R2JNB ACC.4, KERRRR AMOV R2, AAJMP COLUMKERR: AJMP BEGINCCSCAN: MOV DPTR, #7F02HMOV A, #00HMOVX @DPTR, AINC DPTRMOVX A, @DPTRCPL AANL A, #03HRETCLEAR: MOV DPTR, #7F01HMOV A, #00HMOVX @DPTR, ARETINIT: MOV 53H, #06H ;分十位MOV 52H, #00H ;分个位MOV 51H, #00H ;秒十位MOV 50H, #00H ;秒个位MOV 54H, #00H ;存放当前工作模式, 00:Reset, 01 Start, 02 Pause, 03 StopMOV 55H, #0AH ;定时计数用, 定时器每次中断0.1s, 计数10次, 定时1sCLR TR0MOV TMOD, 01H ;定时器工作在方式1, 16位定时器MOV TH0, #3CHMOV TL0, #0B0HRETDIS: PUSH ACCPUSH 00HPUSH 03HMOV A, #03HMOV DPTR, #7F00HMOVX @DPTR, AMOV R0, #50HMOV R3, #0EFHMOV A, 54HCJNE A, #03H, DIS0MOV R0, #60HDIS0: MOV A, R3AGAIN: MOV DPTR, #7F02HMOVX @DPTR, AMOV A, @R0MOV DTPR, DAT ASMOVC A, @A+DPTRMOV DPTR, #7F01HMOVX @DPTR, AACALL DL1MSINC R0MOV A, R3JNB ACC.0, OUTRL AMOV R3, AAJMP AGAINOUT: POP 03HPOP 00HPOP ACCRETDAT AS: DB 03FH, 06H, 05BH, 04FH, 066H, 06DH, 07DH DB 07H, 7FH, 6FH, 77H, 7CH, 39H, 5EH, 79H, 71HDL1MS: MOV R7, #01HDL0: MOV R6, #0FFHDL1: DJNZ R6, DL1DJNZ R7, DL0RETPUTBUF: MOV R1, AJNZ CHKSTAR TACALL RESETFUNCSJMP GOBACKCHKSTAR T: CJNE R1, #03H, CHKPAUSEACALL STAR TFUNCSJMP GOBACKCHKPAUSE: CJNE R1, #04H, CHKSTOPACALL PAUSEFUNCSJMP GOBACKCHKSTOP: CJNE R1, #07H, CHKOTHERACALL STOPFUNCSJMP GOBACKCHKOTHER: ACALL OTHERFUNCGOBACK: RETRESETFUNC: MOV R0, 54HCJNE R0, #00H, RESET0RETCJNE R0, #01H, RESET0RETRESET0: ACALL INITMOV 54H, #00HRETSTAR TFUNC: MOV R0, 54HCJNE R0, #01H, STAR T0RETSTAR T0: MOV 54H, #00HSETB TR0RETPAUSEFUNC: MOV R0, 54HCJNE R0, #01H, PAUSE0CLR TR0MOV 54H, #02HSJMP PAUSE1PAUSE0: CJNE R0, #02H, PAUSE1SETB TR0MOV 54H, #01HPAUSE1: RETSTOPFUNC: MOV R0, 54HCJNE R0, #03H, STOP0MOV 54H, #02HMOV R0, #50HMOV R1, #60HSTOP1: MOV A, @R1MOV @R0, AINC R0INC R1CJNE R0, #54H, STOP1RETSTOP0: CLR TR0MOV 54H, #03HMOV R0, #60HMOV R1, #50HSTOP2: MOV A, @R1MOV @R0, AINC R0INC R1CJNE R1, #54H, STOP2RETOTHERFUNC: MOV R0, 54HCJNE R0, #03H, OTHER0CJNE R1, #01H, OTHER1MOV R0, #63HINC @R0CJNE @R0, #06H, OTHER0MOV @R0, #00HSJMP OTHER0OTHER1: CJNE R1, #02H, OTHER2MOV R0, #62HINC @R0CJNE @R0, #0AH, OTHER0MOV @R0, #00HSJMP OTHER0OTHER2: CJNE R1, #05H, OTHER3MOV R0, #61HINC @R0CJNE @R0, #06H, OTHER0MOV @R0, #00HSJMP OTHER0OTHER3: CJNE R1, #06H, OTHER0MOV R0, #60HINC @R0CJNE @R0, #0AH, OTHER0MOV @R0, #00HSJMP OTHER0OTHER0: RET;使用定时器0, 工作模式1, 定时0.1s, 晶振频率为6MHz;定时器初值X = 65536 –50000 = 15536 = 3CB0HTIMER0: MOV TH0, #3CHMOV TL0, #0B0HDJNZ 55H, EXIT0 ;判断是否已定时中断10, 即1秒MOV 55H, #0AHMOV R0, #50HGOON0: DEC @R0CJNE @R0, #0FFH, EXIT0MOV @R0, #09HINC R0DEC @R0CJNE @R0, #0FFH, EXIT0MOV @R0, #05HINC R0DEC @R0CJNE @R0, #0FFH, EXIT0MOV @R0, #09HINC R0DEC @R0CJNE @R0, #0FFH, EXIT0 ; 倒计时结束, 停止计时, 显示全”0”ACALL INITMOV 53H, #00HMOV 54H, #03HEXIT0: RET。