ch12_s4.asm

51单片机基础篇 对于有一定基础的人看看 包含书中所以的源代码

;PROGRAM NAME S4.ASM
;TEST SERIAL PORT MODE 1 INPUT TEST
;
BUZZER		REG	P3.4
LED		REG	P3.7
;
RESET		MOV	R0,#00H
     		DJNZ	R0,$
     		CLR	LED
     		CLR	BUZZER
;
     		LCALL	INIT_SIO
START		CLR	RI		
WAIT		JNB	RI,WAIT			;WAIT UNTIL RI=1
     		MOV	A,SBUF			;READ A CHARACTER
     		NOP
     		NOP
     		NOP
     		NOP
     		MOV	SBUF,A			;OUTPUT TO SBUF
     		CJNE	A,#'!',START
;
STOP		SJMP	STOP			;ENDLESS  LOOP
;
INIT_SIO	
     		MOV	TMOD,#00100000B 	;TIMER 1 MODE 2
     		MOV	TH1,#FDH		;BAUD RATE=9600 b/s
     		SETB	TR1			;START TIMER 1
     		MOV	SCON,#01010000B 	;ENABLERECEIVE
     		RET				;1 START,8 BITDATA,1 STOP BIT