;Very simple 4 bit 2 Line LCD Driver

DATA EQU P1    ;D4=P1.4,D5=P1.5,D6=P1.6 AND D7=P1.7
RS   EQU P1.0  ;RS=P1.0
EN   EQU P1.1  ;EN=P1.1
;))))))))))))))))))))))))))))))))))
     ORG 00H

START:
      MOV 40H,#'D'
      MOV 41H,#'P'   
      MOV 42H,#'P'
      MOV 43H,#'R'
      MOV 44H,#' '
      MOV 45H,#'S'
      MOV 46H,#'Y'   
      MOV 47H,#'S'
      MOV 48H,#'T'
      MOV 49H,#'E'
      MOV 4AH,#'M'
      MOV 4BH,#'S'   
      MOV 4CH,#' '
      MOV 4DH,#'B'
      MOV 4EH,#'N'
      MOV 4FH,#'D'
      
lcall MAIN1  ;for line 1
      MOV 40H,#'D'
      MOV 41H,#'P'   
      MOV 42H,#'P'
      MOV 43H,#'R'
      MOV 44H,#' '
      MOV 45H,#'S'
      MOV 46H,#'Y'   
      MOV 47H,#'S'
      MOV 48H,#'T'
      MOV 49H,#'E'
      MOV 4AH,#'M'
      MOV 4BH,#'S'   
      MOV 4CH,#' '
      MOV 4DH,#'S'
      MOV 4EH,#'D'
      MOV 4FH,#'D'

lcall MAIN2  ;for line 2
     LCALL 4DELAY
     LCALL 4DELAY
     SJMP START
;****************************************


MAIN1:
	MOV A,#28h    ;RE-INIT LCD 2LINE 587 MATRIX
	LCALL COMNWRT ;CALL COMMAND SUBRUTINE I
	LCALL DELAY1   ;GIVE LCD SOME TIME
	MOV A,#0EH    ;DISPLAY ON CURSOR ON
	LCALL COMNWRT ;CALL COMMAND SUBRUTINE II
	LCALL DELAY1   ;GIVE LCD SOME TIME
	MOV A,#06h    ;SIFT CURSOR RIGHT
	LCALL COMNWRT ;CALL COMMAND SUBRUTINE
	LCALL DELAY1   ; GIVE LCD SOME TIME
	MOV A,#02H    ;CURSOR AT LINE 1,POS.1
	LCALL COMNWRT ;CALL COMMAND SUBRUTINE
	LCALL DELAY1   ;GIVE LCD SOME TIME
	clr a
        LJMP 0LCDDATA
;;************************************************
MAIN2:
	MOV A,#28h    ;RE-INIT LCD 2LINE 587 MATRIX
	LCALL COMNWRT ;CALL COMMAND SUBRUTINE I
	LCALL DELAY1   ;GIVE LCD SOME TIME
	MOV A,#0EH    ;DISPLAY ON CURSOR ON
	LCALL COMNWRT ;CALL COMMAND SUBRUTINE II
	LCALL DELAY1   ;GIVE LCD SOME TIME
	MOV A,#06h    ;SIFT CURSOR RIGHT
	LCALL COMNWRT ;CALL COMMAND SUBRUTINE
	LCALL DELAY1   ; GIVE LCD SOME TIME
	MOV A,#0C0H    ;CURSOR AT LINE 2,POS.1
	LCALL COMNWRT ;CALL COMMAND SUBRUTINE
	LCALL DELAY1   ;GIVE LCD SOME TIME
	clr a
		
;;************************************************

0LCDDATA:MOV A,40H             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,41H             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,42H             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,43H             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,44H             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,45H             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,46H             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,47H             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,48H             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,49H             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,4AH             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,4BH             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,4CH             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,4DH             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,4EH             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV A,4FH             ;DISPLAY DATA START HERE 
	LCALL DATAWRT ;CALL DISPLAY SUBRUTINE
	LCALL DELAY1  ; GIVE LCD SOME TIME
	MOV DATA,#0FFH
	RET

	
    


W_NIB:	PUSH  ACC           	;Save A for low nibble
		ORL   DATA,#0F0h    	;Bits 4..7 <- 1
		ORL   A,#0Fh        	;Don't affect bits 0-3
		ANL   DATA,A        	;High nibble to display
		SETB  EN 
		CLR   EN 
		POP   ACC           	;Prepare to send
		SWAP  A             	;...second nibble
		ORL   DATA,#0F0h    	; Bits 4...7 <- 1
		ORL   A,#0Fh       	; Don't affect bits 0...3
		ANL   DATA,A        	;Low nibble to display
		SETB  EN 
		CLR   EN 
		RET

COMNWRT:	    ;SEND COMMAND TO LCD
	
	CLR RS   ;FOR RS=0 COMMAND
	LCALL W_NIB
	LCALL DELAY1 ;GIVE LCD SOME TIME
	RET

DATAWRT: ;WRITE DATA TO LCD
         SETB RS   ;FOR RS=1 COMMAND
	     LCALL W_NIB
         LCALL DELAY1 
	     RET
DELAY1:MOV R2,#10			
HERE3: MOV R3,#20	
HERE2: DJNZ R3,HERE2
       DJNZ R2,HERE3
       RET    

;**********************************************************************





4DELAY:ACALL DELAY
       ACALL DELAY
       ACALL DELAY
       ACALL DELAY
       RET


           
DELAY: MOV R3,#255 ;DELAY2 FOR HOLD DATA
HERE5: MOV R2,#255
HERE4:  DJNZ R2,HERE4
		DJNZ R3,HERE5
        RET	         

END