14． 4×4矩陣式鍵盤(pán)識別技術(shù)
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如圖4.14.2所示，用AT89S51的并行口P1接4×4矩陣鍵盤(pán)，以P1.0－P1.3作輸入線(xiàn)，以P1.4－P1.7作輸出線(xiàn)；在數碼管上顯示每個(gè)按鍵的“0－F”序號。對應的按鍵的序號排列如圖4.14.1所示
（1．把“單片機系統“區域中的P3.0－P3.7端口用8芯排線(xiàn)連接到“4X4行列式鍵盤(pán)”區域中的C1－C4R1－R4端口上；
（2．把“單片機系統”區域中的P0.0/AD0－P0.7/AD7端口用8芯排線(xiàn)連接到“四路靜態(tài)數碼顯示模塊”區域中的任一個(gè)a－h(huán)端口上；要求：P0.0/AD0對應著(zhù)a，P0.1/AD1對應著(zhù)b，……，P0.7/AD7對應著(zhù)h。
4．
（1．4×4矩陣鍵盤(pán)識別處理
（2．每個(gè)按鍵有它的行值和列值，行值和列值的組合就是識別這個(gè)按鍵的編碼。矩陣的行線(xiàn)和列線(xiàn)分別通過(guò)兩并行接口和CPU通信。每個(gè)按鍵的狀態(tài)同樣需變成數字量“0”和“1”，開(kāi)關(guān)的一端（列線(xiàn)）通過(guò)電阻接VCC，而接地是通過(guò)程序輸出數字“0”實(shí)現的。鍵盤(pán)處理程序的任務(wù)是：確定有無(wú)鍵按下，判斷哪一個(gè)鍵按下，鍵的功能是什么；還要消除按鍵在閉合或斷開(kāi)時(shí)的抖動(dòng)。兩個(gè)并行口中，一個(gè)輸出掃描碼，使按鍵逐行動(dòng)態(tài)接地，另一個(gè)并行口輸入按鍵狀態(tài)，由行掃描值和回饋信號共同形成鍵編碼而識別按鍵，通過(guò)軟件查表，查出該鍵的功能。
5．
P3=FFH,P3.0=0
P3=FFH,P3.1=0
P3=FFH,P3.2=0
P3=FFH,P3.3=0
KEYBUFEQU30H
ORG00H
START:MOVKEYBUF,#2
WAIT:
MOVP3,#0FFH
CLRP3.4
MOVA,P3
ANLA,#0FH
XRLA,#0FH
JZNOKEY1
LCALLDELY10MS
MOVA,P3
ANLA,#0FH
XRLA,#0FH
JZNOKEY1
MOVA,P3
ANLA,#0FH
CJNEA,#0EH,NK1
MOVKEYBUF,#0
LJMPDK1
NK1:CJNEA,#0DH,NK2
MOVKEYBUF,#1
LJMPDK1
NK2:CJNEA,#0BH,NK3
MOVKEYBUF,#2
LJMPDK1
NK3:CJNEA,#07H,NK4
MOVKEYBUF,#3
LJMPDK1
NK4:NOP
DK1:
MOVA,KEYBUF
MOVDPTR,#TABLE
MOVCA,@A+DPTR
MOVP0,A
DK1A:MOVA,P3
ANLA,#0FH
XRLA,#0FH
JNZDK1A
NOKEY1:
MOVP3,#0FFH
CLRP3.5
MOVA,P3
ANLA,#0FH
XRLA,#0FH
JZNOKEY2
LCALLDELY10MS
MOVA,P3
ANLA,#0FH
XRLA,#0FH
JZNOKEY2
MOVA,P3
ANLA,#0FH
CJNEA,#0EH,NK5
MOVKEYBUF,#4
LJMPDK2
NK5:CJNEA,#0DH,NK6
MOVKEYBUF,#5
LJMPDK2
NK6:CJNEA,#0BH,NK7
MOVKEYBUF,#6
LJMPDK2
NK7:CJNEA,#07H,NK8
MOVKEYBUF,#7
LJMPDK2
NK8:NOP
DK2:
MOVA,KEYBUF
MOVDPTR,#TABLE
MOVCA,@A+DPTR
MOVP0,A
DK2A:MOVA,P3
ANLA,#0FH
XRLA,#0FH
JNZDK2A
NOKEY2:
MOVP3,#0FFH
CLRP3.6
MOVA,P3
ANLA,#0FH
XRLA,#0FH
JZNOKEY3
LCALLDELY10MS
MOVA,P3
ANLA,#0FH
XRLA,#0FH
JZNOKEY3
MOVA,P3
ANLA,#0FH
CJNEA,#0EH,NK9
MOVKEYBUF,#8
LJMPDK3
NK9:CJNEA,#0DH,NK10
MOVKEYBUF,#9
LJMPDK3
NK10:CJNEA,#0BH,NK11
MOVKEYBUF,#10
LJMPDK3
NK11:CJNEA,#07H,NK12
MOVKEYBUF,#11
LJMPDK3
NK12:NOP
DK3:
MOVA,KEYBUF
MOVDPTR,#TABLE
MOVCA,@A+DPTR
MOVP0,A
DK3A:MOVA,P3
ANLA,#0FH
XRLA,#0FH
JNZDK3A
NOKEY3:
MOVP3,#0FFH
CLRP3.7
MOVA,P3
ANLA,#0FH
XRLA,#0FH
JZNOKEY4
LCALLDELY10MS
MOVA,P3
ANLA,#0FH
XRLA,#0FH
JZNOKEY4
MOVA,P3
ANLA,#0FH
CJNEA,#0EH,NK13
MOVKEYBUF,#12
LJMPDK4
NK13:CJNEA,#0DH,NK14
MOVKEYBUF,#13
LJMPDK4
NK14:CJNEA,#0BH,NK15
MOVKEYBUF,#14
LJMPDK4
NK15:CJNEA,#07H,NK16
MOVKEYBUF,#15
LJMPDK4
NK16:NOP
DK4:
MOVA,KEYBUF
MOVDPTR,#TABLE
MOVCA,@A+DPTR
MOVP0,A
DK4A:MOVA,P3
ANLA,#0FH
XRLA,#0FH
JNZDK4A
NOKEY4:
LJMPWAIT
DELY10MS:
MOVR6,#10
D1:MOVR7,#248
DJNZR7,$
DJNZR6,D1
RET
TABLE:DB3FH,06H,5BH,4FH,66H,6DH,7DH,07H
DB7FH,6FH,77H,7CH,39H,5EH,79H,71H
END
7．
#include
unsignedcharcodetable[]={0x3f,0x06,0x5b,0x4f,
0x66,0x6d,0x7d,0x07,
0x7f,0x6f,0x77,0x7c,
0x39,0x5e,0x79,0x71};
unsignedchartemp;
unsignedcharkey;
unsignedchari,j;
voidmain(void)
{
while(1)
{
P3=0xff;
P3_4=0;
temp=P3;
temp=temp&0x0f;
if(temp!=0x0f)
{
for(i=50;i>0;i--)
for(j=200;j>0;j--);
temp=P3;
temp=temp&0x0f;
if(temp!=0x0f)
{
temp=P3;
temp=temp&0x0f;
switch(temp)
{
case0x0e:
key=7;
break;
case0x0d:
key=8;
break;
case0x0b:
key=9;
break;
case0x07:
key=10;
break;
}
temp=P3;
P1_0=~P1_0;
P0=table[key];
temp=temp&0x0f;
while(temp!=0x0f)
{
temp=P3;
temp=temp&0x0f;
}
}
}
P3=0xff;
P3_5=0;
temp=P3;
temp=temp&0x0f;
if(temp!=0x0f)
{
for(i=50;i>0;i--)
for(j=200;j>0;j--);
temp=P3;
temp=temp&0x0f;
if(temp!=0x0f)
{
temp=P3;
temp=temp&0x0f;
switch(temp)
{
case0x0e:
key=4;
break;
case0x0d:
key=5;
break;
case0x0b:
key=6;
break;
case0x07:
key=11;
break;
}
temp=P3;
P1_0=~P1_0;
P0=table[key];
temp=temp&0x0f;
while(temp!=0x0f)
{
temp=P3;
temp=temp&0x0f;
}
}
}
P3=0xff;
P3_6=0;
temp=P3;
temp=temp&0x0f;
if(temp!=0x0f)
{
for(i=50;i>0;i--)
for(j=200;j>0;j--);
temp=P3;
temp=temp&0x0f;
if(temp!=0x0f)
{
temp=P3;
temp=temp&0x0f;
switch(temp)
{
case0x0e:
key=1;
break;
case0x0d:
key=2;
break;
case0x0b:
key=3;
break;
case0x07:
key=12;
break;
}
temp=P3;
P1_0=~P1_0;
P0=table[key];
temp=temp&0x0f;
while(temp!=0x0f)
{
temp=P3;
temp=temp&0x0f;
}
}
}
P3=0xff;
P3_7=0;
temp=P3;
temp=temp&0x0f;
if(temp!=0x0f)
{
for(i=50;i>0;i--)
for(j=200;j>0;j--);
temp=P3;
temp=temp&0x0f;
if(temp!=0x0f)
{
temp=P3;
temp=temp&0x0f;
switch(temp)
{
case0x0e:
key=0;
break;
case0x0d:
key=13;
break;
case0x0b:
key=14;
break;
case0x07:
key=15;
break;
}
temp=P3;
P1_0=~P1_0;
P0=table[key];
temp=temp&0x0f;
while(temp!=0x0f)
{
temp=P3;
temp=temp&0x0f;
}
}
}
}
}
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