Real Time Clock interfacing with 8051


Sample code for Real Time Clock interfacing with 8051.
Following code can be using for 8051 and 8052 ICs like: 89c51, 89c52, 89s51, 89s52, 89c2051. 


;=========================================================
;    Downloaded from www.projectsof8051.com
;    MicroTronics Technologies
;=========================================================
;====RTCTIME.ASM: SETTING TIME,READING AND DISPLAYING IT=========
        ORG 0000H
        ACALL  DELAY_200ms       ;RTC NEEDS 200ms UPON POWER UP
        SETB P3.6
        CLR P3.6
;====TURNING ON  THE  RTC=========================================
        MOV DPTR,#10        ;R0=0AH,REG. A ADDRESS
        MOV A,#20H        ;010 IN D6-D4 TO TURN ON OSC.
        MOVX  @DPTR,A        ;SEND IT TO REGISTER A OF RTC

;====SETTING THE  TIME  MODE======================================
        SETB P3.6
        CLR P3.6
        MOV DPTR,#11        ;REG. B ADDRESS
        MOV A,#83H        ;BCD,24 HRS ,DAYLIGHT SAVING
        MOVX @DPTR,A        ;SEND IT TO REG R


;====SETTING THE TIME=========================================
        SETB P3.6
        CLR P3.6
 OUT1:      ACALL DELAY
        MOV DPTR,#00        ;POINT TO SECONDS ADDRESS
        MOV A,#01H        ;SECONDS=00H
        MOVX @DPTR,A        ;SET SECONDS
        SETB P3.6
        CLR P3.6
        ACALL DELAY
        MOV DPTR,#02        ;POINT TO MINUTES ADDRESS
        MOV A,#03H        ;MINUTES=O00H
        MOVX @DPTR,A        ;SET MINUTES
        
        SETB P3.6
        CLR P3.6
        ACALL DELAY
        MOV DPTR,#04        ;POINT TO HOURS ADDRESS
        MOV A,#02H        ;HOURS=00H
        MOVX @DPTR,A        ;SET HOURS

        SETB P3.6
        CLR P3.6
        ACALL DELAY
        MOV DPTR,#11        ;REG B ADDRESS
        MOV A,#03        ;D7=0 OF REG B TO ALLOW UPDATE
        MOVX @DPTR,A        ; SEND IT TO REGISTER B
        SETB P3.6        ;DISABLING THE WRITE SIGNAL
       
;====INITIALSING LCD============================================
        
        MOV A,#80H
        ACALL command
        MOV A,#38H
        ACALL command
        MOV A,#0EH
        ACALL command
        MOV A,#01H
        ACALL command
        ACALL  delay
        MOV A,#80H
        ACALL command
        MOV DPTR,#LINE_1
      NXT1: MOV A,#00H
        MOVC A,@A+DPTR
        JZ OUTx
        ACALL DISPLAY        ;/--("TIME:")
        INC DPTR
        SJMP NXT1

;====READING TIME==============================================

outx:
AGAIN1:     MOV DPTR,#04
        SETB P3.7
        CLR P3.7        ;SET READ
        ACALL DELAY
        MOVX A,@DPTR        ;READ SECONDS
        MOV P0,A
        ACALL DISPLAYNUM
        MOV A,#':'
        ACALL DISPLAY
        
        MOV DPTR,#02        ;POINT TO SEC. LOC.
        SETB P3.7
        CLR P3.7        ;SET READ
        ACALL DELAY
        MOVX A,@DPTR        ;READ SECONDS
        MOV P0,A
        ACALL DISPLAYNUM
        MOV A,#':'
        ACALL DISPLAY
        

        MOV DPTR,#00        ;POINT TO SEC. LOC.
        SETB P3.7
        CLR P3.7        ;SET READ
        ACALL DELAY
        MOVX A,@DPTR        ;READ SECONDS
        MOV P0,A
        ACALL DISPLAYNUM
        ACALL DELAY_1SEC
        MOV A,#86H        ;GOING BACK TO 1ST LINE & 6TH POSITION
        ACALL command
        SJMP AGAIN1
     
;====LCD COMMAND & DATA SUBROUTINE=============================      

command:        acall ready
        mov p1,a
        clr p3.3
        clr p3.4
        setb p3.5
        clr p3.5
        ret
ready:        setb p1.7
        clr p3.3
        setb p3.4
check1:        clr p3.5
        setb p3.5
        jb p1.7,check1
        ret
display:        acall ready
        mov p1,a
        setb p3.3
        clr p3.4
        setb p3.5
        clr p3.5
        ret

DISPLAYNUM:
        MOV B,A
        SWAP A
        ANL A,#0FH
        ORL A,#30H
        
        ACALL DISPLAY
        MOV A,B
        ANL A,#0FH
        ORL A,#30H
        ACALL DISPLAY
        RET 
        
;====DELAY SUBROUTINE======================================
;====200MSEC SUBROUTINE======================================
DELAY_200ms:
        MOV R1,#4
HERE1:        MOV R2,#250
HERE:        NOP
        NOP
        DJNZ R2,HERE
        DJNZ R1,HERE1
        RET
;====SIMPLE DELAY==========================================

delay:        
        MOV R1,#10
        HERE11:        MOV R2,#0FAH
        HEREX:  NOP
        NOP
        DJNZ R2,HEREX
        DJNZ R1,HERE11
        RET
;====ONE SECOND DELAY===================================

DELAY_1SEC:     MOV TMOD,#01        ;Timer 0, 16-bitmode
        mov r1,#0Ah
xx2:        mov r0,#64h
        
xx1:        MOV TL0,#0FDh        ;TL0=0, the low byte
        MOV TH0,#92h        ;TH0=0, the high byte
        SETB TR0        ;Start timer 0
AGAIN:        JNB TF0,AGAIN
        djnz r0,xx1
        djnz r1,xx2        ;Monitor timer flag 0
        CLR TR0        ;Stop the timer 0
        CLR TF0        ;Clear timer 0 flag
here1:        sjmp here1

;====

org 350h
    LINE_1: DB 'TIME: ',0

    END

;=========================================================
;    Downloaded from www.projectsof8051.com
;    MicroTronics Technologies
;=========================================================
LED interfacing program