ch13_s9.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 S9.ASM
     ;TEST SERIAL PORT (MODE 3)
     ADDR    	EQU     27H
     STOP    	EQU     00H
     BUZZER  	REG     P3.4
     LED     	REG     P3.7
     ;
             	ORG     0000H
     RESET   	MOV     R0,#00H
             	DJNZ    R0,$
             	CLR     LED
             	CLR     BUZZER
     ;
     START   	LCALL   INIT_SIO  		;SIO,TIMER INIT
             	CLR     RI
             	MOV     P1,#00H    		;CLEAR P1 PORT
             	SETB    SM2         		;MULTIPROCESSOR COMMUNICATION
     WAIT    	JNB     RI,WAIT    		;WAIT UNTIL RI=1
             	MOV     A,SBUF      		;READ ADDRESS
             	CLR     RI
             	CJNE    A,#ADDR,WAIT		;ADDRESS CHECK
             	CLR     SM2             	;SM2=0,READ DATA MODE
     DWAIT   	JNB     RI,DWAIT
             	MOV     A,SBUF          	;READ DATA
             	CLR     RI
             	SETB    SM2             	;MULTIPROCESSOR COMMUNICATION
             	CJNE    A,#STOP,WAIT   	        ;WAIT ANOTHER CODE
             	SJMP    START           	;RE-START
     ;
     INIT_SIO
             	MOV     TMOD,#00100000B 	;TIMER 1 MODE 2
             	MOV     TH1,#FDH        	;BAUD RATE=9600b/s
             	SETB    TR1             	;START TIMER 1
             	MOV     SCON,#11010000B	        ;T/R,1 START BIT
                                     		;8 BITDATA,1 TB8,1 STOP BIT
             	RET
     ;
     DELAY   	MOV     R0,#00H         	;WAIT A WHILE
              	MOV     R1,#00H
     DLY1    	DJNZ    R0,$
             	DJNZ    R1,DLY1
             	RET
     ;