16f873;RS232硬件编程

winnie

RCDATA  EQU  30H
RCFLAG  EQU  31H
RCOneSIGN EQU  0
RCWrong  EQU  5
#INCLUDE <P16877.INC>
org 0
nop
goto start
org 4
intentr
goto intsever
;____________________________
org 9
start
clrf RCFLAG
clrf RCDATA
InitUart
bsf  STATUS,RP0
bcf  RCFLAG,RCOneSIGN
movlw b'10111111' ;TX=output
movwf TRISC
movlw b'10100110'
movwf TXSTA
movlw 19h
movwf SPBRG  ;9600,high speed mode
bsf  STATUS,RP0
movlw b'00100000'
movwf PIE1
movlw b'11000000'
movwf INTCON
bcf  STATUS,RP0
movlw b'10010000'
movwf RCSTA
main
btfsc RCFLAG,RCOneSIGN
goto TXLoop
;btfss RCFLAG,RCWrong
goto main
TXLoop
bcf  STATUS,RP0
movf RCDATA,w
movwf TXREG
bsf  STATUS,RP0
btfss TXSTA,TRMT
goto $-2
bcf  STATUS,RP0
bcf  RCFLAG,RCOneSIGN
goto main
;*****************************
intsever
movf STATUS,w
btfsc STATUS,RP0
bcf  STATUS,RP0
movwf RCFLAG
btfsc RCSTA,OERR
goto RCerror  
movf RCREG,w
movwf RCDATA
bsf  RCFLAG,RCOneSIGN
retfie
RCerror
bcf  STATUS,RP0
bcf  RCSTA,CREN
movf RCREG,w
movf RCREG,w
movlw b'10010000'
movwf RCSTA
btfsc RCFLAG,RCWrong
bsf  STATUS,RP0
clrf RCFLAG
retfie
;----------------
end
注意，这个程序是先收再发的，如果接收不到数据那么发送也就不启动。