串口自我传送.asm

刚学时编的小程序

OUT EQU 30H

ORG 0H
JMP BEGIN

BEGIN:MOV SP,#60H
	CALL INIT_RS232
	MOV OUT,#0

RUN:JNB TI,$
	CLR TI
	MOV SBUF,OUT

WAIT:
	JB RI,RX_READY
	JMP WAIT
RX_READY:
	CLR RI
	MOV A,SBUF
	MOV P1,A

	MOV R5,#30
	CALL DELAY

	MOV A,OUT
	CPL A
	MOV OUT,A
	JMP RUN

INIT_RS232:
	MOV SCON,#50H
	MOV TMOD,#20H
	MOV TH1,#0FDH
	SETB TR1
	SETB TI
	RET

DELAY:
	MOV R6,#50
ASD:MOV R7,#100
FGH:DJNZ R7,FGH
	DJNZ R6,ASD
	DJNZ R5,DELAY
	RET