89S52 giao tiếp LCD 16x2 chế độ 4 bit tại cổng P1

[teenbg97]

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$mod51
;+++++++++++++++++++++++++++variables
;++++++++++++++++++++++++++++++++++++

  U equ 31        ;memory location to hold upper nibble
  L equ 32 ;memory location to hold lower nibble

  Port equ P1      ;data port to connect LCD
  RS equ P1.0      ;RS pin connection
  RW equ P1.1      ;RW pin connection
  EN equ P1.2      ;EN pin connection

  ;connection of Port
  ;Port.1-Port.3 (not used)
  ;Port.4 = DB4
  ;Port.5 = DB5
  ;Port.6 = DB6
  ;Port.7 = DB7
;+++++++++++++++++++++++++++++++++++++
  ORG 0000h
  CLR RW
  ACALL init

  MOV A, #'T'     ;SEND "TENTUTS.COM 4BIT" 
  ACALL lcd_data     ;in first line of LCD
  MOV A, #'E'
  ACALL lcd_data
  MOV A, #'N'
  ACALL lcd_data
  MOV A, #'T'
  ACALL lcd_data
  MOV A, #'U'
  ACALL lcd_data
  MOV A, #'T'
  ACALL lcd_data
  MOV A, #'S'
  ACALL lcd_data
  MOV A, #'.'
  ACALL lcd_data
  MOV A, #'C'
  ACALL lcd_data
  MOV A, #'O'
  ACALL lcd_data
  MOV A, #'M'
  ACALL lcd_data
  MOV A, #' '
  ACALL lcd_data
  MOV A, #'4'
  ACALL lcd_data
  MOV A, #'B'
  ACALL lcd_data
  MOV A, #'I'
  ACALL lcd_data
  MOV A, #'T'
  ACALL lcd_data

  MOV A, #0c0H         ;switch to 2nd line of LCD
  ACALL lcd_cmd  

  MOV A, #'M'     ;SEND "MODE USING 2 PORT" 
  ACALL lcd_data     ;in SECOND line of LCD
  MOV A, #'O'
  ACALL lcd_data
  MOV A, #'D'
  ACALL lcd_data
  MOV A, #'E'
  ACALL lcd_data
  MOV A, #' '
  ACALL lcd_data
  MOV A, #'U'
  ACALL lcd_data
  MOV A, #'S'
  ACALL lcd_data
  MOV A, #'I'
  ACALL lcd_data
  MOV A, #'N'
  ACALL lcd_data
  MOV A, #'G'
  ACALL lcd_data
  MOV A, #' '
  ACALL lcd_data
  MOV A, #'2'
  ACALL lcd_data
  MOV A, #'P'
  ACALL lcd_data
  MOV A, #'O'
  ACALL lcd_data
  MOV A, #'R'
  ACALL lcd_data
  MOV A, #'T'
  ACALL lcd_data
  
  SJMP $     ;INFINITE LONG LOOP

;+++++++++++++++++++++++++++++Separator
;++++++++++++++++++++++++++++++++++++++

 
separator:
   MOV U,A        ;save A at temp location U
   ANL U,#0F0H    ;mask it  with 0Fh (28h & F0h = 20h) 
   SWAP A         ;swap nibble (28h => 82H)
   ANL A,#0F0H    ;mask it with 0fh (82h & f0h = 80h)
   MOV L,A        ;save it at temp location L
   RET            ;return

;++++++++++++++++++++++++++Move To Port 
;++++++++++++++++++++++++++++++++++++++

move_to_Port:
   MOV port,A       ;put content of A to port
   SETB EN    ;make EN high
   ACALL DELAY   ;call a short delay routine
   CLR EN     ;clear EN
   ACALL DELAY   ;short delay
   RET     ;return

            
;++++++++++++++++++++++++++LCD command 
;++++++++++++++++++++++++++++++++++++++

   lcd_cmd:
    CLR RS     ;clear rs, going to send command
    ACALL separator     ;separate the command and save to U and L
    MOV A, U     ;copy U to A
    ACALL move_to_port  ;move content of a to port 
    MOV A, L            ;copy L to A
    ACALL move_to_port  ;move content of a to port
    RET       ;return
 
;++++++++++++++++++++++++++++++LCD data
;++++++++++++++++++++++++++++++++++++++

  lcd_data:
   SETB RS            ;RS=1, going to send DATA
   ACALL separator    ;separate the data and save to U & L
   MOV A, U           ;copy U to A
   ACALL move_to_port ;send it to LCD
   MOV A, L           ;copy L to A
   ACALL move_to_port ;send it to LCD
   RET                ;return

;+++++++++++++++++++++++++Initilization
;++++++++++++++++++++++++++++++++++++++

init:
   ACALL delay     ;some delay to lcd after power on
   ACALL delay

   MOV port, #20h  ;send 20h to lcd to set 4 bit mode
   CLR RS   ;after that we can use lcd_cmd
   SETB EN         ;make EN switching
   ACALL delay
   CLR EN

   MOV A, #28H
   ACALL lcd_cmd
   MOV A, #0CH
   ACALL lcd_cmd
   MOV A, #06H
   ACALL lcd_cmd
   MOV A, #01H
   ACALL lcd_cmd
   RET

;+++++++++++++++++++++++++++++++++Delay
;++++++++++++++++++++++++++++++++++++++

delay:
   MOV R0, #10H
  L2: MOV R1,#0FH
  L1: DJNZ R1, L1
   DJNZ R0, L2
   RET

;+++++++++++++++++++++++++++++++++++++++

end