,,,; LCD Display Driver Demo.
,,,; Timing code assumes 1.2MHz Clock
,,,
,,,;LCD Registers addresses
,,,LCD_CMD_WR      equ     0
,,,LCD_DATA_WR     equ     1
,,,LCD_BUSY_RD     equ     2
,,,LCD_DATA_RD     equ     3
,,,
,,,;LCD Commands
,,,LCD_CLS         equ     1
,,,LCD_HOME        equ     2
,,,LCD_SETMODE     equ     4
,,,LCD_SETVISIBLE  equ     8
,,,LCD_SHIFT       equ     16
,,,LCD_SETFUNCTION equ     32
,,,LCD_SETCGADDR   equ     64
,,,LCD_SETDDADDR   equ     128
,,,
,,,;Reset vector
,,,        org 0000h
0000,02 01 6A,,        jmp start
,,,
,,,
,,,;Start of the program
,,,        org 0100h
,,,
0100,20 21 21 20,string1a,string1a:db ' !! A M A Z I N G !! '
0115,00,,         db 0
0116,21 21 20 41,string1b,string1b:db '!! A M A Z I N G !! '
012A,00,,         db 0
012B,20 41 20 76,string2,string2:db ' A virtual LM032L... '
0140,00,,        db 0
,,,
0141,20 64 72 69,string3,string3:db ' driven by a virtual '
0156,00,,        db 0
0157,20 20 20 38,string4,string4:db '   8051 processor!'
0169,00,,        db 0
,,,
016A,74 38,start,start:  mov A,#038h
016C,12 02 11,,        call wrcmd
,,,
016F,74 0E,loop,loop:   mov A,#LCD_SETVISIBLE+6         ;Make the display & blink visible:
0171,12 02 11,,        call wrcmd
,,,
0174,7F 02,,        mov R7,#2
0176,,loop2,loop2:
0176,90 01 00,,        mov DPTR,#string1a
0179,12 01 DF,,        call wrstr
,,,
017C,90 00 C8,,        mov DPTR,#200
017F,12 02 2C,,        call wtms
,,,
0182,74 01,,        mov A,#LCD_CLS                  ;Clear screen
0184,12 02 11,,        call wrcmd
,,,
0187,90 01 16,,        mov DPTR,#string1b
018A,12 01 DF,,        call wrstr
,,,
018D,90 00 C8,,        mov DPTR,#200
0190,12 02 2C,,        call wtms
,,,
0193,74 01,,        mov A,#LCD_CLS                  ;Clear screen
0195,12 02 11,,        call wrcmd
,,,
0198,DF DC,,        djnz R7,loop2
,,,
019A,90 01 00,,        mov DPTR,#string1a
019D,12 01 DF,,        call wrstr
,,,
01A0,90 01 90,,        mov DPTR,#400
01A3,12 02 2C,,        call wtms
,,,
01A6,74 C0,,        mov A,#LCD_SETDDADDR+64
01A8,12 02 11,,        call wrcmd
,,,
01AB,90 01 2B,,        mov DPTR,#string2
01AE,12 01 F5,,        call wrslow
,,,
01B1,90 00 C8,,        mov DPTR,#200
01B4,12 02 2C,,        call wtms
,,,
01B7,74 01,,        mov A,#LCD_CLS                  ;Clear screen
01B9,12 02 11,,        call wrcmd
,,,
01BC,90 01 41,,        mov DPTR,#string3
01BF,12 01 F5,,        call wrslow
,,,
01C2,74 C0,,        mov A,#LCD_SETDDADDR+64
01C4,12 02 11,,        call wrcmd
,,,
01C7,90 01 57,,        mov DPTR,#string4
01CA,12 01 F5,,        call wrslow
,,,
01CD,74 0F,,        mov A,#LCD_SETVISIBLE+7         ;Show the blink cursor as well.
01CF,12 02 11,,        call wrcmd
,,,
01D2,90 07 D0,,        mov DPTR,#2000
01D5,12 02 2C,,        call wtms
,,,
01D8,74 01,,        mov A,#LCD_CLS                  ;Clear screen
01DA,12 02 11,,        call wrcmd
,,,
01DD,80 90,,        jmp loop
,,,
,,,
,,,;Sub routine to write null terminated string at DPTR in program ram.
01DF,78 01,wrstr,wrstr:  mov R0,#LCD_DATA_WR
01E1,E4,wrstr1,wrstr1: clr A
01E2,93,,        movc A,@A+DPTR
01E3,60 0F,,        jz wrstr2
01E5,F2,,        movx @R0,A
01E6,12 02 1A,,        call wtbusy
01E9,A3,,        inc DPTR
01EA,C0 82,,        push DPL
01EC,C0 83,,        push DPH
01EE,D0 83,,        pop DPH
01F0,D0 82,,        pop DPL
01F2,80 ED,,        jmp wrstr1
01F4,22,wrstr2,wrstr2: ret
,,,
,,,;Sub routine to write null terminated string at DPTR in program ram. Slowly
01F5,78 01,wrslow,wrslow: mov R0,#LCD_DATA_WR
01F7,E4,wrslw1,wrslw1: clr A
01F8,93,,        movc A,@A+DPTR
01F9,60 15,,        jz wrslw2
01FB,F2,,        movx @R0,A
01FC,12 02 1A,,        call wtbusy
01FF,A3,,        inc DPTR
0200,C0 82,,        push DPL
0202,C0 83,,        push DPH
0204,90 00 64,,        mov DPTR,#100
0207,12 02 2C,,        call wtms
020A,D0 83,,        pop DPH
020C,D0 82,,        pop DPL
020E,80 E7,,        jmp wrslw1
0210,22,wrslw2,wrslw2: ret
,,,
,,,
,,,;Sub routine to write command:
0211,78 00,wrcmd,wrcmd:  mov R0,#LCD_CMD_WR
0213,F2,,        movx @R0,A
0214,02 02 1A,,        jmp wtbusy
,,,
,,,
,,,;Sub routine to write character:
0217,78 01,wrchar,wrchar: mov R0,#LCD_DATA_WR
0219,F2,,        movx @R0,A
,,,
,,,;Subroutine to wait for busy clear
021A,79 02,wtbusy,wtbusy: mov R1,#LCD_BUSY_RD
021C,E3,,        movx A,@r1
021D,20 E7 FA,,        jb ACC.7,wtbusy
0220,22,,        ret
,,,
,,,;Wait for number of seconds in A
0221,C0 E0,wtsec,wtsec:  push ACC
0223,12 02 2C,,        call wtms
0226,D0 E0,,        pop ACC
0228,14,,        dec A
0229,70 F6,,        jnz wtsec
022B,22,,        ret
,,,
,,,;Wait for number of milliseconds in DPTR
022C,63 82 FF,wtms,wtms:   xrl DPL,#0FFh                   ;Can't do DEC DPTR, so do the loop by forming 2's complement
022F,63 83 FF,,        xrl DPH,#0FFh                   ;and incrementing instead.
0232,A3,,        inc DPTR
0233,75 8A 9C,wtms1,wtms1:  mov TL0,#09Ch                   ;100 ticks before overflow = 1ms at 1.2MHz Clock
0236,75 8C FF,,        mov TH0,#0FFh
0239,75 89 01,,        mov TMOD,#1                     ;Timer 0 mode 1
023C,D2 8C,,        setb TCON.4                     ;Timer 0 runs
023E,30 8D FD,wtms2,wtms2:  jnb TCON.5,wtms2
0241,C2 8C,,        clr TCON.4                      ;Timer 0 stops
0243,C2 8D,,        clr TCON.5
0245,A3,,        inc DPTR
0246,E5 82,,        mov A,DPL
0248,45 83,,        orl A,DPH
024A,70 E7,,        jnz wtms1
024C,22,,        ret
,,,
,,,
000E,,,        END