ORG 0
			LJMP MAIN
			
			ORG 23H
			LJMP SERIAL
			
ORG 30H

MAIN:		MOV P1,#0FFH
			MOV TMOD,#20H
			MOV TH1,#0FAH
			MOV SCON,#50H
			MOV IE,#10010000B
			SETB TR1
			MOV R0,#'L'

BACK:		
			CPL P1.2
			MOV A,R0
			MOV SBUF,A
			JNB TI,$

AGN:		INC	R3
			ACALL DELAY
			ACALL DELAY
			ACALL DELAY 
			ACALL DELAY
			CJNE R3,#0FH,AGN
			
			MOV R3,#00H
			SJMP BACK
			
			
;;;;;;;;;;;
SERIAL:		
			
			JNB RI,TRANS
			MOV A,SBUF
			MOV R0,A
			CLR RI
			RETI	
			
			
TRANS:		CLR TI
			RETI


;;;;;;DELAY
DELAY:		MOV R1,#00H
AGAIN:		INC R1
			CJNE R1,#0FFH,AGAIN
			RET

			
END