;Check busy flag before sending data, command to LCD
;P1=data pin
;P2.0 connected to RS pin
;P2.1 connected to R/W pin
;P2.2 connected to E pin
        ORG
        MOV     A,#38H   ;init. LCD 2 lines,5x7 matrix
        ACALL   COMMAND       ;issue command 
        MOV     A,#0EH        ;LCD on, cursor on
        ACALL   COMMAND       ;issue command 
        MOV     A,#01H        ;clear LCD command
        ACALL   COMMAND       ;issue command
        MOV     A,#06H        ;shift cursor right
        ACALL   COMMAND       ;issue command 
        MOV     A,#86H        ;cursor: line 1, pos. 6
        ACALL   COMMAND       ;command subroutine
        MOV     A,#'N'        ;display letter N
        ACALL   DATA_DISPLAY
        MOV     A,#'O'        ;display letter O
        ACALL   DATA_DISPLAY
HERE:   SJMP    HERE          ;STAY HERE
COMMAND: ACALL   READY        ;is LCD ready?
        MOV     P1,A          ;issue command code
        CLR     P2.0          ;RS=0 for command
        CLR     P2.1          ;R/W=0 to write to LCD
        SETB    P2.2          ;E=1 for H-to-L pulse
        CLR     P2.2          ;E=0 ,latch in
        RET
DATA_DISPLAY:
        ACALL   READY         ;is LCD ready?
        MOV     P1,A          ;issue data  
        SETB    P2.0          ;RS=1 for data
        CLR     P2.1          ;R/W=0 to write to LCD
        SETB    P2.2          ;E=1 for H-to-L pulse
        CLR     P2.2          ;E=0, latch in 
        RET

READY:
     SETB    P1.7             ;make P1.7 input port
     CLR     P2.0        ;RS=0 access command reg
     SETB    P2.1        ;R/W=1 read command reg
;read command reg and check busy flag
BACK:CLR     P2.2        ;E=1 for H-to-L pulse
     SETB    P2.2        ;E=0 H-to-L pulse
     JB      P1.7,BACK        ;stay until busy flag=0
     RET
     END