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单片机3个普通IO识别22个按键

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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S51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: ATC2051 * * 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[]= //键码映射表 {// 0 1 2 3 4 5 6 7 8 9

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 } }

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