单片机LCD1602显示程序（汇编），小弟有很多地方不懂，希望高人能加上注释，有助于本人学习

; LCD Display Driver Demo.

; Timing code assumes 1.2MHz Clock

;LCD Registers addresses

LCD_CMD_WR equ 0 ；宏定义

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；程序开始入口地址0x00

jmp start；跳转到start处

;Start of the program

org 0100h

string1a:db ' !! A M A Z I N G !! ' ；表格，要显示的内容。

db 0

string1b:db '!! A M A Z I N G !! '

db 0

string2:db ' A virtual LM032L... '

db 0

string3:db ' driven by a virtual '

db 0

string4:db ' 8051 processor!'

db 0

start: mov A,#038h ;为什么是38h：查1602数据手册，38h的命令

call wrcmd

loop: mov A,#LCD_SETVISIBLE+6 ;Make the display & blink visible:

call wrcmd

mov R7,#2

loop2:

mov DPTR,#string1a

call wrstr

mov DPTR,#200

call wtms

mov A,#LCD_CLS ;Clear screen

call wrcmd

mov DPTR,#string1b

call wrstr

mov DPTR,#200

call wtms

mov A,#LCD_CLS ;Clear screen

call wrcmd

djnz R7,loop2

mov DPTR,#string1a

call wrstr

mov DPTR,#400

call wtms

mov A,#LCD_SETDDADDR+64

call wrcmd

mov DPTR,#string2

call wrslow

mov DPTR,#200

call wtms

mov A,#LCD_CLS ;Clear screen

call wrcmd

mov DPTR,#string3

call wrslow

mov A,#LCD_SETDDADDR+64

call wrcmd

mov DPTR,#string4

call wrslow

mov A,#LCD_SETVISIBLE+7 ;Show the blink cursor as well.

call wrcmd

mov DPTR,#2000

call wtms

mov A,#LCD_CLS ;Clear screen

call wrcmd

jmp loop

;Sub routine to write null terminated string at DPTR in program ram.

wrstr: mov R0,#LCD_DATA_WR

wrstr1: clr A

movc A,@A+DPTR

jz wrstr2

movx @R0,A

call wtbusy

inc DPTR

push DPL

push DPH

pop DPH

pop DPL

jmp wrstr1

wrstr2: ret

;Sub routine to write null terminated string at DPTR in program ram. Slowly

wrslow: mov R0,#LCD_DATA_WR

wrslw1: clr A

movc A,@A+DPTR

jz wrslw2

movx @R0,A

call wtbusy

inc DPTR

push DPL

push DPH

mov DPTR,#100

call wtms

pop DPH

pop DPL

jmp wrslw1

wrslw2: ret

;Sub routine to write command:

wrcmd: mov R0,#LCD_CMD_WR

movx @R0,A

jmp wtbusy

;Sub routine to write character:

wrchar: mov R0,#LCD_DATA_WR

movx @R0,A

;Subroutine to wait for busy clear

wtbusy: mov R1,#LCD_BUSY_RD

movx A,@r1

jb ACC.7,wtbusy

ret

;Wait for number of seconds in A

wtsec: push ACC

call wtms

pop ACC

dec A

jnz wtsec

ret

;Wait for number of milliseconds in DPTR

wtms: xrl DPL,#0FFh ;Can't do DEC DPTR, so do the loop by forming 2's complement

xrl DPH,#0FFh ;and incrementing instead.

inc DPTR

wtms1: mov TL0,#09Ch ;100 ticks before overflow = 1ms at 1.2MHz Clock

mov TH0,#0FFh

mov TMOD,#1 ;Timer 0 mode 1

setb TCON.4 ;Timer 0 runs

wtms2: jnb TCON.5,wtms2

clr TCON.4 ;Timer 0 stops

clr TCON.5

inc DPTR

mov A,DPL

orl A,DPH

jnz wtms1

ret

END