di2519.txt
;*************************************************************************************************
; LISTING 1 - SAMPLE DATA DISPLAY; 8051 CODE FOR DATA DISPLAY ON LCD
;
; PROGRAM LISTING FOR SAMPLE DATA DISPLAY ON LCD SCREEN.
; ALPHANUMERIC LCD MODULE 1 LINE x 16 CHARACTERS TYPE
; WRITTEN BY : BHARAT D. METHA
; 
; "Interface LCD with ease," EDN, April 27, 2000, pg 142
; http://www.ednmag.com/ednmag/reg/2000/042700/designideas.htm#09di6
;********************************************************************************************** 
temp1:  reg     20h
Dat:    reg     P1.0
Clk:    reg     P1.1
RS:     reg     P1.2
ENA:    reg     P1.3
;;;;;;;;;;;;;;;;  Main progarm   ;;;;;;;;;;;;;;
        org     0000h
        jmp     start
        org     30h
start:  call    INT
        mov     dptr,#title
        mov     r0,#10h         ;counter for  data transfer
loop1:  clr	    a
  movc    a,@a+dptr
        mov     temp1,a
        djnz    r0,loop2
        call    dly
        jmp     start
loop2:  call    sr_tx
        setb    RS      ;This part transfer data to LCD.
        setb    ENA
        call    delay   ;small delay
        clr     ENA
        clr     RS
        inc     dptr
        jmp     loop1
title:  db "Hello,EDN Reader"
;;;;;;;;;;;;;;;;;  Main program End  ;;;;;;;;;;;
;------  Sub-Routine  programs  --------
;;; initialization of LCD screen.  
INT:    mov     sp,#60h
        clr     RS
        clr     ENA
        mov     temp1,#38h
        call   disp2
        mov     temp1,#01h
        call    disp2
        mov     temp1,#02h
        call    disp2
        mov     temp1,#06h
  call    disp2
        ret
;;;;;;;;;;;;;;;;;;;;;;;;;; 
disp2:  call    sr_tx   
        setb    ENA
        mov     r3,#0ffh
        djnz    r3,$
        clr     ENA
        ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; program to transfer data serially from I/O 
sr_tx:  mov    r1,#08h         ;counter
s1:     mov     a,temp1
        clr     c
        rlc     a
        mov     temp1,a       
        mov     Dat,c
        setb    Clk
        nop
        nop
        clr     Clk
        djnz    r1,s1
        
        ret
;;;;;;;; Delay Sub-Routine   ;;;;;;;;;;;;;;;
; this delay program is a flexible loop , any time delay can 
; be adjusted by changing the value of registers
dly:    mov     r5,#0fh
d1:     acall   mdly
        djnz    r5,#d1
        ret
mdly:   mov     r6,#0ffh
mdly1:  call    delay
        djnz    r6,mdly1
        ret
delay:  mov     r7,#0ffh
        djnz    r7,$
        
  ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
end