3.asm

来自「串口通信 频率测量 EEPROM读写程序」· 汇编 代码 · 共 53 行

       
          .include "c:\appnotes\8515def.inc"
          .org $000
           rjmp main
           .org $008
           rjmp SPI_TXC    
          .org $00d
     MAIN: ldi r17,$5f
           out SPL,r17
           ldi r17,$02
           out SPH,r17  ;setup STACK pointer in internal SRAM so that
                       ;RCALL and interrupt subroutine can use it for
                       ; return
           ldi r25,$80
           out SREG,r25 ;enable globle interrupt          
           ldi r17,$08
           out WDTCR,r17;enable wacthdog
           wdr          ;reset wachdog
           ser r16
           out DDRB,r16 ;portb is output mode and turn off all LEDS                           
           sbi DDRB,5    ;set MOSI(PB.5) output mode whwn SPI is master.
           sbi DDRB,7    ;set SCK (PB.7) output mode when SPI is master
           sbi DDRB,4    ;set SS output mode so that this byte cann't
                         ;influence SPI master work mode .
           ldi r17,0b11111100
           out SPCR,r17  ;set SPIE,SPE,MSTR,CPOL,CPHA ,reset the others   
           ldi r21,$73
           out SPDR , r21 ;,the rightest LED display "P"  
           ldi r17,$01
           out PORTB,r17 ;PB.0 output 1                                                                                                             
           rcall delay           
           wdr                      
           ldi r21,$00
           out SPDR,r21 ; turn off "P" at the rightest LED; 
           rcall delay          
           rjmp main
   SPI_TXC:sbi SPCR,4
           reti
   delay:  clr r15
           ldi r21,$18
        d2:ldi r22,$ff 
        d1:ldi r23,$ff
        d0:dec r23
           wdr
           cp r23,r15
           brne d0            
           dec r22
           cp r22,r15           
           brne d1
           dec r21
           cp r21,r15
           brne d2
           ret