2.asm

串口通信 频率测量 EEPROM读写程序

       
          .include "c:\appnotes\8515def.inc"
          .org $000
           rjmp main
           .org $00a
           rjmp UART_DRE
           .org $00b
           rjmp UART_TXC
          .org $00d
     MAIN: ldi r25,$80
           out SREG,r25 ;enable globle interrupt
           clr r15
           ser r16
           out DDRB,r16 ;portb is output mode and turn off all LEDS                           
           sbi UCR,5
           ldi r21,$73
           out UDR , r21           
           inc r15
           out PORTB,r15 ;portb output 1 ,the rightest LED display "P"                       
           ldi r20,$3
           out UBRR,r20 ;set baud rate at 8Mhz 115200
           sbi UCR,3
    trans: sbis UCR,6           
           rjmp trans
           rcall d0                       
           ldi r21,$00 
           sbi UCR,5
           out UDR,r21 ; turn off "P" at the rightest LED
   trans1: sbis UCR,6
           rjmp trans1           
           rcall d0             
           rjmp main
        d0:clr r15
           ldi r22,$1 ;ser r22
        d1:ldi r23,$1 ;ser r23
     delay:dec r23
           cp r23,r15
           brne delay            
           dec r22
           cp r22,r15           
           brne d1
           ret
    UART_DRE:out UDR,r21
             cbi UCR,6 ; clear TXCIE byte at UCR
             reti
    UART_TXC:reti