p13_1.asm

单片机原理与应用实例教程 单片机原理与应用实例教程

		COL1 EQU P2.2
		COL2 EQU P2.1
		COL3 EQU P2.0
		
		ORG 0000H
		LJMP MAIN
		ORG 4100H
TAB:	DB 40h, 4FH, 24H, 30H, 19H
		DB 12H, 02H, 78H, 00H, 10H

MAIN:	MOV DPTR, #TAB
		MOV P0, #0FFH

LOOP:	ACALL INPUT
		ACALL DELAY
		AJMP LOOP

INPUT:	JNB COL1, RETURN
		JNB COL2, RETURN
		JNB COL3, RETURN
		MOV R0, #0H
		MOV R1, #0H
		MOV A, #11011111B
SCAN:	MOV P3, A
		JB COL1, J_COL2
		MOV R0, #1
		AJMP KEYDN
J_COL2:	JB COL2, J_COL3
		MOV R0, #2
		AJMP KEYDN
J_COL3:	JB COL3, NEXT
		MOV R0, #3
		AJMP KEYDN
NEXT:	RL A
		INC R1
		INC R1
		INC R1
		CJNE R1, #9, SCAN
		AJMP RETURN
KEYDN:	MOV A, R0
		ADD A, R1
		MOVC A, @A+DPTR
		MOV P0, A
RETURN:	MOV P3, #0FFH
		RET

DELAY:	MOV R6, #0FFH
DL1:	DJNZ R6, DL1
		RET

		END