Stm32矩阵键盘扫描程序分析

我们知道在51单片机中，通过扫描某个口的电平高低得知那个按键按下，比如，控制两行4列，

 

假如让P1=0xCf;低位都置1 （pb0-pb3），pb4-pb5置0；然后我们就扫描P1口就行了，如果有按键被按下的，高电平会被强制拉低的。

假如按键返回的值为0xce,可知是pb0被拉低了，由此可判断是S1或者S2按下了，其他的同理。

当然只让P1=0xcf,是不能判断出具体的按键是哪个的，此时，如果我们取反既P1=0x30;

当按键返回值为0x10时，我们可得知01 0000，pb5=0，s1或者s2被按下，这个时候我们将0xce|0x10=0xde,就是唯一的值了。以此类推，得出其他的值来。

在stm32中是同样的大道理；

uint8_t KeyScan(void)

{

    uint8_t HangValue = 0;

    uint8_t LieValue  = 0;

    uint16_t KeyValue  = 0;

    uint8_t Tmp =0;

    static uint8_t KeyConter = 0;

   

    GPIO_SetBits(Colum1.port, (Colum1.pin|Colum2.pin|Colum3.pin|Colum4.pin));         

    GPIO_ResetBits(Line1.port,(Line1.pin|Line2.pin));

 Tmp = GPIO_ReadInputData(Line1.port);

    if ((Tmp&0x0F) != 0x0F)

    {

        if (KeyConter < 1)

        {//去抖

            KeyConter++;

       }

       else

        {           

              HangValue = Tmp&0x0f;     

 

                            GPIO_ResetBits(Colum1.port, (Colum1.pin|Colum2.pin|Colum3.pin|Colum4.pin));  

            GPIO_SetBits(Line1.port,(Line1.pin|Line2.pin));

           Tmp = GPIO_ReadInputData(Colum1.port);

            LieValue = Tmp&0x30;

             KeyValue = (HangValue)|LieValue;

 if (KeyValue)// KeyValue^KeyValueBkp

            {                

                KeyValueBkp = KeyValue;

                switch (KeyValue)

                {

                                                                   

          //      case KEY_10:    return KEY_NUM_0;//16;----0

                case KEY_01:    return KEY_NUM_1;//3;-----1

                case KEY_02:    return KEY_NUM_2;//4;-----2

                case KEY_03:    return KEY_NUM_3;//5;-----3               

                case KEY_04:    return KEY_NUM_4;//7;-----4

                case KEY_05:    return KEY_NUM_5;//8;-----5

                case KEY_06:    return KEY_NUM_6;//9;-----6               

                case KEY_07:    return KEY_NUM_7;//11----7

                case KEY_08:    return KEY_NUM_8;//------8

                default:

                    return 0;

                }               

            }

            else

            {

                return 0;

            }

        }

    }

    else

    {

        KeyConter = 0;  //计数清零

        KeyValueBkp = 0;

    }  

   

    return 0;

}

 

 

 

 

typedef struct

{

    GPIO_TypeDef        *port;

    uint16_t    pin;

}Matrix_t;

 

 

//const Matrix_t Colum1 = {GPIOD, GPIO_PIN_2};

//const Matrix_t Colum2 = {GPIOD, GPIO_PIN_3};

//const Matrix_t Colum3 = {GPIOD, GPIO_PIN_4};

const Matrix_t Colum1 = {GPIOB, GPIO_Pin_0};

const Matrix_t Colum2 = {GPIOB, GPIO_Pin_1};

const Matrix_t Colum3 = {GPIOB, GPIO_Pin_2};

const Matrix_t Colum4 = {GPIOB, GPIO_Pin_3};

 

const Matrix_t Line1  = {GPIOB, GPIO_Pin_4};

const Matrix_t Line2  = {GPIOB, GPIO_Pin_5};

#define KEY_01 0x1e

#define KEY_02 0x2e

#define KEY_03 0x1d

#define KEY_04 0x2d

#define KEY_05 0x1b

#define KEY_06 0x2b

#define KEY_07 0x17

#define KEY_08 0x27