NAME	LCD_Display_Control

PROG	SEGMENT	CODE
STACK	SEGMENT IDATA
VAR	SEGMENT DATA
BITVAR  SEGMENT BIT

DB0 EQU P1.0
DB1 EQU P1.1
DB2 EQU P1.2
DB3 EQU P1.3
DB4 EQU P1.4
DB5 EQU P1.5
DB6 EQU P1.6
DB7 EQU P1.7
EN EQU P3.7
RS EQU P3.6
RW EQU P3.5
LCDDATA EQU P1

	RSEG VAR
count:	DS	1

	RSEG BITVAR
last_line:	DBIT	1

	RSEG STACK
	DS	10H

	CSEG	AT	0
	USING	0
	JMP	START

	RSEG	PROG
;hello world test program
START:
MOV  SP,#STACK-1	; initialize the stack
MOV  PSW,#00  		; start using register bank 0
LCALL INIT_LCD
LCALL CLEAR_LCD
LCALL HELLO_WORLD
MAIN_LOOP:
ORL PCON, #01		; put processor to sleep
;return from interrupt here (red-eye), and go back to sleep
JMP MAIN_LOOP


;checks the busy bit
WAIT_LCD:
	SETB EN ;Start LCD command
	CLR RS ;It's a command
	SETB RW ;It's a read command
	MOV LCDDATA,#0FFh ;Set all pins to FF initially
	MOV A,LCDDATA ;Read the return value
	JB ACC.7,WAIT_LCD ;If bit 7 high, LCD still busy
	CLR EN ;Finish the command
	CLR RW ;Turn off RW for future commands
RET

;initialize the LCD
INIT_LCD:
	SETB EN
	CLR RS
	MOV LCDDATA,#38h
	CLR EN
	LCALL WAIT_LCD
	SETB EN
	CLR RS
	MOV LCDDATA,#0Eh
	CLR EN
	LCALL WAIT_LCD
	SETB EN
	CLR RS
	MOV LCDDATA,#06h	;trying to add scrolling, originally #06h
	CLR EN
	LCALL WAIT_LCD
RET

;write a character out to the LCD
WRITE_TEXT:
	SETB EN
	SETB RS
	MOV LCDDATA,A
	CLR EN
	LCALL WAIT_LCD
RET

;clear the display
CLEAR_LCD:
	SETB EN
	CLR RS
	MOV LCDDATA,#01h
	CLR EN
	LCALL WAIT_LCD
RET

LINE2:
	SETB EN
	CLR RS
	MOV LCDDATA,#0C0h
	CLR EN
	LCALL WAIT_LCD
RET

LINE1:
	SETB EN
	CLR RS
	MOV LCDDATA,#080h
	CLR EN
	LCALL WAIT_LCD
RET

RETURN_HOME:
	SETB EN
	CLR RS
	MOV LCDDATA,#02h
	CLR EN
	LCALL WAIT_LCD
RET
	
;the initial string to appear when the power is turned on
HELLO_WORLD:
	MOV A,#'R'
	LCALL WRITE_TEXT
	MOV A,#'o'
	LCALL WRITE_TEXT
	MOV A,#'b'
	LCALL WRITE_TEXT
	MOV A,#'o'
	LCALL WRITE_TEXT
	MOV A,#'t'
	LCALL WRITE_TEXT
	MOV A,#' '
	LCALL WRITE_TEXT
	MOV A,#'M'
	LCALL WRITE_TEXT
	MOV A,#'a'
	LCALL WRITE_TEXT
	MOV A,#'n'
	LCALL WRITE_TEXT
	MOV A,#'i'
	LCALL WRITE_TEXT
	MOV A,#'a'
	LCALL WRITE_TEXT
	MOV A,#'!'
	LCALL WRITE_TEXT
	LCALL LINE2
	MOV A,#'T'
	LCALL WRITE_TEXT
	MOV A,#'h'
	LCALL WRITE_TEXT
	MOV A,#'e'
	LCALL WRITE_TEXT
	MOV A,#' '
	LCALL WRITE_TEXT
	MOV A,#'M'
	LCALL WRITE_TEXT
	MOV A,#'A'
	LCALL WRITE_TEXT
	MOV A,#'X'
	LCALL WRITE_TEXT
	MOV A,#'X'
	LCALL WRITE_TEXT
	MOV A,#' '
	LCALL WRITE_TEXT
	MOV A,#'P'
	LCALL WRITE_TEXT
	MOV A,#'r'
	LCALL WRITE_TEXT
	MOV A,#'o'
	LCALL WRITE_TEXT
	MOV A,#'j'
	LCALL WRITE_TEXT
	MOV A,#'e'
	LCALL WRITE_TEXT
	MOV A,#'c'
	LCALL WRITE_TEXT
	MOV A,#'t'
RET

END