1.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         
           ldi r16,0b00000000;turn off all LEDS
           out PORTB,r16
           ldi r21,$73
           sbi UCR,3
           out UDR,r21
           inc r16
           out PORTB,r16 ;portb output 1 ,the rightest LED light "P"                       
           ldi r20,$3
           out UBRR,r20 ;set baud rate at 8Mhz 115200
           ldi r21,$73              
   trans0: sbis USR,5
           rjmp trans0 ;is UART data register empty?
           sbi UCR,3   ;enable UART translate data
           out UDR,r21 ;output "P" letter to LED
;;****************************************************************
  ;when programme is excuted,"P" letter cann't be
  ;displayed on the rightest LED ,why? Please give me
  ;detail technique information as soon as possible .
  ; Please tell me how to use RXD ,TXD and 74ls164 to extend serial
  ; I/O port in AVR MCU and how to translate data to 74ls164 . I cann't
  ; find answer in AVR RISC MCU data book AUGUST 1999.   
  ; Thank you very much ! 
  ; E-mail :
  ; My name is JIANG CHUN LIN ,electronic R&D senior engineer
  ; in China PRC . 
  ; POST BOX : NANGJIN 202 post box 119 branch JIANGSU province
  ;            China PRC.                                
;;****************************************************************** 
      tr0:sbis USR,6
           rjmp tr0    ;translation over?    
           rcall d0
           ldi r21,$00          
      tr1: sbis USR,5
           rjmp tr1 
           sbi UCR,3   ;enable UART translate data
           out UDR,r21
        t0:sbis USR,6
           rjmp t0    ;translation over?    
           rcall d0               
           rjmp main
        d0: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:reti
    UART_TXC:reti