Microcontroller learning record - independent button

Hardware Hookup 

From the circuit connection diagram, we can see that one end of the 8 independent buttons is grounded and the other end is connected to the socket JP5. 

On the development board, JP5 is connected to the P1 port through an external cable. The microcontroller reads the status of the P1 port (0 or 1) to determine which button is pressed.

software design

Writing a key scanning function

/****************************************************** ***********

* Function name: duli_key_scan

* Function: Identify which key is pressed

* Input: None

* Output: key value 1~8

*************************************************** **********/

unsigned char duli_key_scan(void)

{

    static unsigned char key_num;

    if (KEY != 0xff)

    { //Indicates that a key is pressed

        delay10ms(); //delay to eliminate jitter

        if ((KEY != 0xff))

        { //A key is pressed

            switch (KEY)

            {

                case 0xfe :

                    key_num = 1;

                    break;

                case 0xfd :

                    key_num = 2;

                    break;

                case 0xfb :

                    key_num = 3;

                    break;

                case 0xf7 :

                    key_num = 4;

                    break;

                case 0xef :

                    key_num = 5;

                    break;

                case 0xdf :

                    key_num = 6;

                    break;

                case 0xbf :

                    key_num = 7;

                    break;

                case 0x7f :

                    key_num = 8;

                    break;  

            }

        }

    }

    return key_num;

}

According to the key value returned by the key scanning function, write the LED display program to light up different LEDs.

LED display program

void led(unsigned char num)

{

    //Code value when 8 LEDs are lit individually

    unsigned char led[9] = {0x00, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80};

    LED = led[num];

}

Burn to the development board

Note: There are two key modes (the only difference between the two codes is the keyword static) 

The first type: press the light on, release the light off (no static) 

The second type: the light turns on when the button is pressed, and remains unchanged when the button is released until the next press, when the light turns on. (With static).

Extensions 

Buttons move the LED light left and right (button 1 moves right, button 2 moves left) 

Press the button to select the pattern display (each button is like a mode switch, press it to display different modes)