7279time.asm

基于7279 的电子时钟

 ORG 0000H
  LJMP MAIN
  ORG 000BH
  LJMP PT_T0
  TM     BIT 00H		 ;一秒定时标志
  BF_P4  EQU 4FH		 ;40H开始的为扫描缓冲区
  BF_P9  EQU 3FH      	 ;设置指针指向40H,97H开始的单元
  ORG 0010H
MAIN:MOV TMOD,#01H		 ;系统初始化
     MOV IE,#82H
     MOV TH0,#3CH
	 MOV TL0,#0B0H
     MOV SP,#67H
     MOV R6,#20H
	 MOV R0,#30H		   
	 MOV A,#00H           
L0:  MOV @R0,A	   
     INC R0		          ;30H开始的为显示缓冲区
     DJNZ R6,L0
	 MOV BF_P4,#40H
	 MOV BF_P9,#97H 
     MOV 50H,#14H
     CLR TM
	 SETB TR0
L6: JNB TM,L5			   ;主循环，等待刷新
    ACALL XS
L5: SJMP L6
XS:CLR TM				   ;刷新值装入显示缓冲区
   MOV R0,#32H
   MOV R1,#40H
   MOV R6,#03H
S4:MOV A,@R0
   MOV B,A
   SWAP A			   
   ANL A,#0FH
   MOV @R1,A
   MOV A,B
   ANL A,#0FH
   INC R1
   MOV @R1,A
   DEC R0
   INC R1
   DJNZ R6,S4
   RET
DT:
   MOV R0,BF_P4
   MOV R1,BF_P9
ST:
   CLR P1.0		;扫描一位子程序
   MOV R6,#0CH
L2:DJNZ R6,L2
   MOV A,R1
   ACALL STFS
   MOV R6,#04H
L3:DJNZ R6,L3
   MOV A,@R0
   MOV DPTR,#TAB
   MOVC A,@A+DPTR
S1:ACALL STFS
   MOV R6,#02H
L4:DJNZ R6,L4
   SETB P1.0
   INC BF_P4
   DEC BF_P9
   MOV A,R0
   CJNE A,#47H,L7
L7:JC L8
   MOV BF_P4,#40H
   MOV BF_P9,#97H
L8: RET
TAB: DB  7EH,30H,6DH,79H,33H	 ;段数据表
     DB  5BH,5FH,70H,7FH,7BH    
STFS:			                               
     MOV R7,#08H
L_1: RLC A
     MOV P1.2,C
	 SETB P1.1
	 MOV R6,#02H
L_2:  DJNZ R6,L_2
     CLR P1.1
	 MOV R6,#02H
L_3:  DJNZ R6,L_3
     DJNZ R7,L_1
	 RET
PT_T0:			       ;中断子程序
     MOV TH0,#3CH	             ;定时50MS
	 MOV TL0,#0B0H
	 PUSH PSW
	 PUSH ACC
	 MOV PSW,#08H
	 LCALL DT
	 DJNZ 50H,PT_R
	 MOV 50H,#14H
	 SETB TM 	           ;一秒时间到，置位00H，显示刷新
	 MOV R0,#30H	       ;秒加一
	 MOV A,@R0
	 ADD A,#01H
	 DA A
	 MOV @R0,A
	 CJNE A,#60H,PT_R
	 MOV @R0,#00H
	 INC R0
	 MOV A,@R0
	 ADD A,#01H		        ;分加一
	 DA A
	 MOV @R0,A
	 CJNE A,#60H,PT_R
	 MOV @R0,#00H
	 INC R0
	 MOV A,@R0
	 ADD A,#01H		        ;时加一
	 DA A 
	 MOV @R0,A
	 CJNE A,#24H,PT_R
	 MOV @R0,00H
PT_R:POP ACC
	 POP PSW
	 RETI
	 END