<1． 4×4矩阵键盘识别处理

<2． 每个按键有它的行值和列值 ，行值和列值的组合就是识别这个按键的编码。矩阵的行线

和列线分别通过两并行接口和CPU通信。每个按键的状态同样需变成数字量“0”和“1”，开关的一端<列线）通过电阻接VCC，而接地是通过程序输出数字“0”实现的。键盘处理程序的任务是：确定有无键按下，判断哪一个键按下，键的功能是什么；还要消除按键在闭合或断开时的抖动。两个并行口中，一个输出扫描码，使按键逐行动态接地，另一个并行口输入按键状态，由行扫描值和回馈信号共同形成键编码而识别按键，通过软件查表，查出该键的功能。 5． 程序框图

图4.14.3

6． 汇编源程序 KEYBUF EQU 30H ORG 00H

START: MOV KEYBUF,#2 WAIT:

MOV P3,#0FFH

CLR P3.4 MOV A,P3 ANL A,#0FH XRL A,#0FH JZ NOKEY1

LCALL DELY10MS MOV A,P3 ANL A,#0FH XRL A,#0FH JZ NOKEY1 MOV A,P3 ANL A,#0FH

CJNE A,#0EH,NK1 MOV KEYBUF,#0 LJMP DK1

NK1: CJNE A,#0DH,NK2 MOV KEYBUF,#1 LJMP DK1

NK2: CJNE A,#0BH,NK3 MOV KEYBUF,#2 LJMP DK1

NK3: CJNE A,#07H,NK4 MOV KEYBUF,#3 LJMP DK1 NK4: NOP DK1:

MOV A,KEYBUF MOV DPTR,#TABLE MOVC A,@A+DPTR MOV P0,A

DK1A: MOV A,P3 ANL A,#0FH XRL A,#0FH JNZ DK1A NOKEY1:

MOV P3,#0FFH CLR P3.5 MOV A,P3 ANL A,#0FH XRL A,#0FH JZ NOKEY2

LCALL DELY10MS MOV A,P3 ANL A,#0FH XRL A,#0FH JZ NOKEY2 MOV A,P3 ANL A,#0FH

CJNE A,#0EH,NK5 MOV KEYBUF,#4 LJMP DK2

NK5: CJNE A,#0DH,NK6 MOV KEYBUF,#5 LJMP DK2

NK6: CJNE A,#0BH,NK7 MOV KEYBUF,#6 LJMP DK2

NK7: CJNE A,#07H,NK8 MOV KEYBUF,#7 LJMP DK2 NK8: NOP DK2:

MOV A,KEYBUF MOV DPTR,#TABLE MOVC A,@A+DPTR MOV P0,A

DK2A: MOV A,P3 ANL A,#0FH XRL A,#0FH JNZ DK2A NOKEY2:

MOV P3,#0FFH CLR P3.6 MOV A,P3 ANL A,#0FH XRL A,#0FH JZ NOKEY3

LCALL DELY10MS MOV A,P3 ANL A,#0FH XRL A,#0FH JZ NOKEY3 MOV A,P3 ANL A,#0FH

CJNE A,#0EH,NK9 MOV KEYBUF,#8 LJMP DK3

NK9: CJNE A,#0DH,NK10 MOV KEYBUF,#9 LJMP DK3

NK10: CJNE A,#0BH,NK11 MOV KEYBUF,#10 LJMP DK3

NK11: CJNE A,#07H,NK12 MOV KEYBUF,#11 LJMP DK3

NK12: NOP DK3:

MOV A,KEYBUF MOV DPTR,#TABLE MOVC A,@A+DPTR MOV P0,A

DK3A: MOV A,P3 ANL A,#0FH XRL A,#0FH JNZ DK3A NOKEY3:

MOV P3,#0FFH CLR P3.7 MOV A,P3 ANL A,#0FH XRL A,#0FH JZ NOKEY4

LCALL DELY10MS MOV A,P3 ANL A,#0FH XRL A,#0FH JZ NOKEY4 MOV A,P3 ANL A,#0FH

CJNE A,#0EH,NK13 MOV KEYBUF,#12 LJMP DK4

NK13: CJNE A,#0DH,NK14 MOV KEYBUF,#13 LJMP DK4

NK14: CJNE A,#0BH,NK15 MOV KEYBUF,#14 LJMP DK4

NK15: CJNE A,#07H,NK16 MOV KEYBUF,#15 LJMP DK4 NK16: NOP DK4:

MOV A,KEYBUF MOV DPTR,#TABLE MOVC A,@A+DPTR MOV P0,A

DK4A: MOV A,P3 ANL A,#0FH XRL A,#0FH JNZ DK4A NOKEY4: