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问 ;***************************************************************
;Program LCD.ASM
;This Program shows how a LCD with 16 char/ 1 line
;is used with a atmel 8515 and a HD44780 lcd controller
;The crystal is set to 4 MHz
;***************************************************************

.include "8515def.inc"            


;Definitions
.equ        E    = PD0        ;E an Pin PD0
.equ        RW    = PD1        ;RW an Pin PD1
.equ        RS    = PD2        ;RS an Pin PD2
.equ        BF    = PB7        ;Busy flag


;LCD inits
.equ        clear_LCD    = 0b00000001    ;CLEAR DISPLAY
.equ        home_LCD    = 0b00000010    ;return home
.equ        set_LCD        = 0b00111000    ;8 bits,2 line, 5x7 dots
.equ        LCD_on        = 0b00001110    ;LCD on
.equ        entry_mode    = 0b00000110    ;set cursor


;Variable definition

.def        chr    = r0        
.def        buffer    = r16        ;RX/TX Data from LCD
.def        counter    = r17        
.def        temp    = r18
.def        temp2    = r19
.def        temp3    = r20

.CSEG
.ORG        0x00                  ; Program starts at adress 0x00
        rjmp    main         

;**************************************************************   
; Subroutine init
; Init PORTD
;**************************************************************   

init:        ldi     temp,0b11111111    ;PORTD is an output
        out    DDRD,temp
        cbi    PORTD,E        ;E init
        cbi    PORTD,RS
        cbi    PORTD,RW
        ret



;***************************************************************
; Subroutine busy_flag
; Test the LCD for sending another instruction
;***************************************************************

busy_flag:    ldi    temp,0b00000000    ;PORTB is an input
        out    DDRB,temp
                cbi    PORTD,RS    ;send test
                sbi    PORTD,RW    ;Set LCD in read-mode
                sbi    PORTD,E        ;control LCD
        nop
        nop
                sbic    PINB,BF        ;LCD busy?
                rjmp    busy_flag       ;no, again
                cbi    PORTD,E        ;disable LCD
                ret                     ;LCD not busy


;***************************************************************
; Subroutine write_data
; Buffer is the data to be sent
;***************************************************************

write_data:    rcall    busy_flag    ;LCD busy?
                ldi    temp,0b11111111    ;PORTB is an output
        out    DDRB,temp
                sbi    PORTD,RS    ;Send Data
                cbi    PORTD,RW    ;LCD in write-mode
        sbi    PORTD,E        
                out    PORTB,buffer    ;Send buffer Data
                cbi    PORTD,E        ;disable LCD
                ret


;***************************************************************
; Subroutine write_instr
; Sends the instruction for LCD-controller
;***************************************************************

write_instr:    rcall    busy_flag    
                ldi    temp,0b11111111    
        out    DDRB,temp
                cbi    PORTD,RS    
                cbi    PORTD,RW    
        sbi    PORTD,E        
                out    PORTB,buffer    
                cbi    PORTD,E        
                ret


;***************************************************************
; Main
; Text from table is shifted to the right
; **************************************************************

main:        

        ldi temp,low(RAMEND) ;Initialize stackpointer for parts with SW stack
        out SPL,temp
        ldi temp,high(RAMEND) ; Commented out since 1200 does not have SRAM
        out SPH,temp


        rcall    init            

                ldi    buffer,set_LCD        ;set LCD Function
        rcall    write_instr

        ldi    buffer,LCD_on        ;LCD on
        rcall    write_instr

        
        ldi    buffer,clear_LCD    ;Clear LCD
        rcall    write_instr

        ldi    buffer,entry_mode    ;Entry mode
        rcall    write_instr



        ldi    buffer,0b00000000    ;LCD-Start adress
        rcall    write_instr        
        ldi    counter,$0F        
        ldi    ZL,LOW(Tabel1*2)    
        ldi    ZH,HIGH(Tabel1*2)    
loop_msg1:    lpm                
        mov    buffer,chr
        rcall    write_data          
                adiw    ZL,1                    
                dec     counter                 
                brne    loop_msg1        

        ldi    buffer,0b11000000    
        rcall    write_instr        
        ldi    counter,$0F        
        ldi    ZL,LOW(Tabel2*2)    
        ldi    ZH,HIGH(Tabel2*2)    
loop_msg2:    lpm                
        mov    buffer,chr        
        rcall    write_data          
        adiw    ZL,1                   
no_carry2:    dec    counter            
                brne    loop_msg2        

loop:    

    ldi    temp,0b11111111    
    out    DDRC,temp
    ldi    buffer,$FF
    out    PORTC,buffer
    
    ldi     buffer,0b00011100
    rcall    write_instr    
    rcall    delay
    rjmp    loop        

;Tabel1:    .DB "123456789abcdef"
Tabel1:     .DB "Robot     Atmel" ;$00/0F

;Tabel1:    .DB "123456789abcdef"
Tabel2:      .DB "Fever      1999"

DELAY:
    ldi    temp,$FF
    ldi    temp2,$FF
    ldi    temp3,$09
LOOP_delay:
    dec     temp
    brne    LOOP_delay
    dec    temp2
    brne     LOOP_delay
    dec    temp3
    brne     LOOP_delay
    ret


答 1: 好!