51单片机例程-矩阵键盘

仿真电路

元件:

英文名|中文名|属性
:-|:-|:-|:-
7SEG-COM-AN-GRN|绿色7段数码管|-
RX8|8位电阻排|元件值设置为100
BUTTON|按键|-
RES|电阻|元件值设置为10K

电路图:
仿真图:

按键功能类似右侧的键盘。
按下按键数码管显示0-9，o = Abcd。

程序设计

main.c:

#include <AT89X51.H>
#define uchar unsigned char
#define uint unsigned int
//CA(共阳极)数码管字形码
uchar words[16] = {
  0xc0, 0xf9, 0xa4, 0xb0, 0x99, //0-4
  0x92, 0x82, 0xf8, 0x80, 0x90, //5-9
  0xa3, 0xb7,                   //o =
  0x88, 0x83, 0xa7, 0xa1        //Abcd
};
//延时函数
void delay(uint t)
{
uint i;
while (t--)
{
  for (i = 120; i; i--)
    ;
}
}
//键盘扫描，无按键返回0，有按键返回坐标
//左上角为11，右上角为14，左下角为41，右下角为44，以此类推
uchar read_keyboard()
{
uchar i, keycode = 0;
P1 = 0xf0;               //P1前4脚设为高电平，后4脚设为低电平
if ((P1 & 0x0f) != 0x0f) //如果按键被按下，P1的电平会改变
{
  delay(2); //消抖
  if ((P1 & 0x0f) != 0x0f)
  {
    P1 = 0xf0;
    switch (P1) //先确定行
    {
    case 0xe0:
      keycode = 10;
      break; //第一行
    case 0xd0:
      keycode = 20;
      break; //第二行
    case 0xb0:
      keycode = 30;
      break; //第三行
    case 0x70:
      keycode = 40;
      break; //第四行
    }
    // delay(3000);
    P1 = 0x0f;  //对应IO口拉高，以便检测
    switch (P1) //再确定列
    {
    case 0x0e:
      keycode += 1;
      break; //第一列
    case 0x0d:
      keycode += 2;
      break; //第二列
    case 0x0b:
      keycode += 3;
      break; //第三列
    case 0x07:
      keycode += 4;
      break; //第四列
    }
    // delay(3000);
  }
}
return (keycode);
}
//按键坐标转按键键值
uchar code2value(uchar keycode)
{
uchar value;
switch (keycode)
{
case 42:
  value = 0;
  break;
case 31:
  value = 1;
  break;
case 32:
  value = 2;
  break;
case 33:
  value = 3;
  break;
case 21:
  value = 4;
  break;
case 22:
  value = 5;
  break;
case 23:
  value = 6;
  break;
case 11:
  value = 7;
  break;
case 12:
  value = 8;
  break;
case 13:
  value = 9;
  break;
case 41:
  value = 10;
  break;
case 43:
  value = 11;
  break;
case 14:
  value = 12;
  break;
case 24:
  value = 13;
  break;
case 34:
  value = 14;
  break;
case 44:
  value = 15;
  break;
default:
  value = 0;
}
return (value);
}
//主程序
void main()
{
uchar keycode;
P2 = words[0];
for (;;)
{
  keycode = read_keyboard(); //读取按键坐标
  if (keycode)               //有按键被按下
  {
    // P2 = keycode;
    P2 = words[code2value(keycode)]; //先转换键值，然后改变数码管显示
  }
}
}