3个普通IO识别22个按键试验

吸取各位前辈的经验，将之前二极管用量多的问题优化一下，目前不用二极管能接6键，2只二极管能接12键，6只二极管能接18键，9只二极管能接21键，第22键要单独占用3只二极管最不化算。

实验用89S51作试验，电路接线就是P1.2,P1.3,P1.4接键盘，P1.0接显示器。





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/*==================================================================*

* 3个IO接识别22键测试程序 *

* ------------------------------------------------ *

* MCU: AT89C2051 *

* OSC: 12M cysytel *

* 程序设计:Cowboy *

* 程序版本:V1.0 *

*==================================================================*/



#include



//================== IO口线连接 ==================

sbit Bus = P1^0;

sbit IO_a = P1^4;

sbit IO_b = P1^3;

sbit IO_c = P1^2;



//================== 变量声明 ====================

unsigned char Disp_buf[3];

unsigned char Dig;

unsigned char Key_count;

unsigned char bdata Key_state;

sbit KB0 = Key_state^0;

sbit KB1 = Key_state^1;

sbit KB2 = Key_state^2;

sbit KB3 = Key_state^3;

sbit KB4 = Key_state^4;

sbit KB5 = Key_state^5;



//================== 表格数据 ====================

code unsigned char LED_font[24]=

{

0x84,0x9f,0xa2,0x8a,0x99,0xc8,0xc0,0x9e,0x80, //012345678

0x88,0x90,0xc1,0xe4,0x83,0xe0,0xf0,0xff,0xfb, //9abcdef -

};



code unsigned char Key_tab[64]= //键码映射表

{//0123456789

22, 0, 2, 0, 0, 0, 0, 0, 4, 0, //0

0, 0, 0, 0, 0,18, 0, 0, 0, 0, //1X

0, 0, 0, 0, 0, 0, 3,14, 0, 0, //2X

20,10, 6, 0, 0, 0, 0, 0, 1,19, //3X

0, 5, 0, 0, 0,15, 0,11, 0, 0, //4X

0,17, 0, 0,13, 8, 0,21, 0, 9, //5X

16,12, 7, 0 //6X

};



//=============== 检测按键 =================

void Key_scan()

{

unsigned char i;

Key_count --; //扫描次序

Key_count &= 3;

switch (Key_count) //按次序处理

{

case 2: //第一轮扫描

KB0 = IO_b;

KB1 = IO_c;

IO_a = 1;

IO_b = 0;

break;



case 1: //每二轮扫描

KB2 = IO_c;

KB3 = IO_a;

IO_b = 1;

IO_c = 0;

break;



case 0: //每三轮扫描

KB4 = IO_a;

KB5 = IO_b;

IO_c = 1;

break;



default: //每四轮扫描

if (!IO_a) KB0 = 0;

if (!IO_b) KB2 = 0;

if (!IO_c) KB4 = 0;

IO_a = 0;



//======更新显示缓冲区=======

i = Key_tab[Key_state];

if (i == 0)

{

Disp_buf[2] = 0x11; //显示三横

Disp_buf[1] = 0x11;

Disp_buf[0] = 0x11;

}

else

{

Disp_buf[2] = 0x0c; //字符"C"

Disp_buf[1] = i / 10; //键码十位

Disp_buf[0] = B;于 //键码个位

}

Key_state = 0;

}

}





/*===================================================================

ONE WIRE 显示总线驱动程序

===================================================================*/



//=============== 发送一位 =================

void Send_bit(bit Dat)

{

unsigned char i = 3;

if (!Dat) Bus = 0;

else

{

Bus = 0;

Bus = 1;

}

while(--i); //延时8us

Bus = 1;

}



//=============== 总线驱动 =================

void Bus_drive()

{

unsigned char i = 0;

unsigned char Sdat;

Send_bit(1); //Bit6消隐

do Bus = 1; while(--i); //延时768us

do Bus = 0; while(--i); //延时768us

Bus = 1;

Sdat = LED_font[Disp_buf[Dig++]]; //获取显示数据

Send_bit(Sdat & 0x01); //发送位0

Send_bit(Sdat & 0x02); //发送位1

Send_bit(Sdat & 0x04); //发送位2

Send_bit(Sdat & 0x08); //发送位3

Send_bit(Sdat & 0x10); //发送位4

Send_bit(Sdat & 0x20); //发送位5

Send_bit(Dig& 0x01); //发送位选1

Send_bit(Dig& 0x02); //发送位选2

while(--i); //延时512us

Send_bit(Sdat & 0x40); //发送位6

for (i = 7;i> 0;i--) Send_bit(1);//位6移至Dout

if (Dig == 3) Dig = 0;

}



/*===================================================================

延时 5ms 程序

===================================================================*/

void Delay_5ms()

{

while(!TF1);

TF1 = 0;

TH1 = (- 5000) / 256;

TL1 = (- 5000) % 256;

}



/*===================================================================

主程序

===================================================================*/
void main()

{

TMOD = 0x10; //定时器1，16位模式

TCON = 0xc0; //TR1=1;TF1=1;

while(1) //主循环

{

Bus_drive(); //显示总线驱动

Key_scan(); //检测按键

Delay_5ms(); //延时5MS

}