p13_2.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
		ROW1 EQU P2.5
		ROW2 EQU P2.6
		ROW3 EQU P2.7
		LED7 EQU P1
		
		ORG 0000H
		LJMP MAIN
		ORG	0003H
		LJMP INT_0
		ORG 4100H
TAB:	DB 40h, 4FH, 24H, 30H, 19H
		DB 12H, 02H, 78H, 00H, 10H

MAIN:	MOV DPTR, #TAB
		SETB EX0
		SETB IT0
		SETB EA
		MOV LED7, #0FFH
				
LOOP:	CLR ROW1
		CLR ROW2
		CLR ROW3
		SETB COL1
		SETB COL2
		SETB COL3
		AJMP LOOP

INT_0:	CLR EX0
		MOV R0, #0H
		MOV R1, #0H
		MOV A, #11011111B
SCAN:	MOV P2, #0FFH
		MOV P2, 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:	INC R1
		INC R1
		INC R1
		RL A
		CJNE R1, #9, SCAN
		AJMP RETURN
KEYDN:	MOV A, R1
		ADD A, R0
		MOVC A, @A+DPTR
		MOV LED7, A
RETURN: ACALL DELAY 
		SETB EX0
		RETI

DELAY:	MOV R6, #0FFH
DL1:	MOV R7, #0FH
DL2:	DJNZ R7, DL2
		DJNZ R6, DL1
		RET

		END