clr lcdreset ; reset
LCALL WRITE_DELAY ; 40 MICROSEC
setb lcdreset
clr lcdfs
call read_status

MOV PA_BUFFER,#90h ; lcd off curser off
call CNTRL_WRITE
//// ;==================================================================
LCALL WAIT_1SEC
LCALL WAIT_1SEC
call error_status ;read_error flag
clr lcdreset ; reset
LCALL WAIT_1SEC
LCALL WAIT_1SEC
LCALL WAIT_1SEC
setb lcdreset
MAIN:
CPL WD_RESET
jmp main

;==================================================================
CNTRL_WRITE:
setb LCDce
setb LCDcd
setb lcdrd
setb LCDwr
MOV LCD_PORT,PA_BUFFER
nop
clr LCDce
clr LCDwr
LCALL WRITE_DELAY
setb LCDwr
setb LCDce
RET

;==================================================================

DATA_WRITE:
setb LCDce
setb LCDcd
setb lcdrd
setb LCDwr
MOV LCD_PORT,PA_BUFFER
nop
clr LCDcd
clr LCDce
clr LCDwr
LCALL WRITE_DELAY
setb LCDwr
setb LCDce
setb lcdcd
RET
;==================================================================
read_status:
push acc
mov LCD_PORT,#0ffh ; input
setb LCDce
setb LCDcd
setb lcdrd
setb LCDwr
nop
redstag:
clr LCDce
clr lcdrd
LCALL WRITE_DELAY
MOV a,LCD_PORT
;LCALL WRITE_DELAY
setb lcdrd
setb LCDce
anl a,#03h
cjne a,#03h,redstag
pop acc
RET
;==================================================================
error_status:
push acc
mov LCD_PORT,#0ffh ; input
setb LCDce
setb LCDcd
setb lcdrd
setb LCDwr
nop
rederstag:
clr LCDce
clr lcdrd
LCALL WRITE_DELAY
MOV a,LCD_PORT
;LCALL WRITE_DELAY
setb lcdrd
setb LCDce
anl a,#040h
cjne a,#00h,rederstag
pop acc
RET
;==================================================================
lcd contrast is ok it is changing from min to max by pot
the last small code i believe it will change lcd from black to white but it is not . why?
thanks for your responce