9. Independent buttons

Press to connect, release to disconnect.

There are four pins in total. The two pairs that are farther apart are turned on in the initial state. The other two pairs are turned on after being pressed.

TXD connects to P3.0 port, RXD connects to P3.1 port

K1, 2, 3, 4 are connected to P31, P30, P32, P33 respectively, and the other ends are connected to the ground, that is, the port will be pulled low when the button is pressed.

Internal structure map:

Input 1, then output 1;

Input 0, then output 0.

(For example, when the input is 1, the NOT gate outputs 0, the diode is not conducting, and the IO directly outputs 1 from VCC; when the input is 0, the NOT gate outputs 1, the diode is conducting, and the IO outputs 0 from GND)

There is a jitter phenomenon when the electric shock is closed and opened.

Software debouncing or hardware debouncing circuit is required (as shown below)

Hardware debouncing is achieved through RC charge and discharge time. (Higher cost and more complex circuit)

Generally, software is used to eliminate jitter, with a delay of 10ms

Use the independent button k1 to control the state of led1 to reverse. Press it once to reverse. The program is as follows:

#include

typedef unsigned char u8;

typedef unsigned int u16;

sbit led=P2^0; //D1

sbit k1=P3^1;//K1

void delay(u16 i)

{

while(i--);

}

void key()

{

if(k1==0)

{

delay(1000); //10ms delay for debounce

if(k1==0)

{

led=~led; //Reverse the state of led

while(!k1); //Exit only when k1=1, that is, when released

}

}

}

void main()

{

while(1)

{

key();

}

}

Use the independent button k1 to control the LED1 to reverse. When pressed, it turns off, and when released, it turns on. The procedure is as follows:

#include

typedef unsigned char u8;

typedef unsigned int u16;

sbit led=P2^0; //D1

sbit k1=P3^1;//K1

void delay(u16 i)

{

while(i--);

}

void key()

{

if(k1==0)

{

delay(1000); //10ms delay for debounce

if(k1==0)

{

led=~led; //Reverse the state of led

while(!k1);//Until release, the loop stops and the following program is performed

}

}

if(k1==1)    //used for release

{

delay(1000);

if(k1==1)

{

led=~led;

while(k1); //Until closed, the loop stops and the following program is performed

}

}

}

void main()

{

while(1)

{

key();

}

}

Use independent buttons to control whether the dynamic digital tube is displayed. Release the button to display it and press it to turn it off:

#include

typedef unsigned char u8;

typedef unsigned int u16;

sbit LSA=P2^2;

sbit LSB=P2^3;

sbit LSC=P2^4;

sbit k1=P3^1;

u8 code smgduanxuan[16]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,

                     0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};

void delay(u16 i)

{

while(i--);

}

void saomiao()

{

u8 i;

for(i=0;i<8;i++)

{

switch(i)

{

case 0:LSA=0;LSB=0;LSC=0;break;

case 1:LSA=1;LSB=0;LSC=0;break;

case 2:LSA=0;LSB=1;LSC=0;break;

case 3:LSA=1;LSB=1;LSC=0;break;

case 4:LSA=0;LSB=0;LSC=1;break;

case 5:LSA=1;LSB=0;LSC=1;break;

case 6:LSA=0;LSB=1;LSC=1;break;

case 7:LSA=1;LSB=1;LSC=1;break;

}

P0=smgduanxuan[i];

delay(100);

P0=0x00;

}

} 

void main()

{

while(1)

{

saomiao();

while(!k1); //When k1=0, i.e. pressed, the loop will continue, the program will not proceed further, and the digital tube will go out

}

}