Electronic clock based on 51 single chip microcomputer

1 Using LCD1602 to display hours and minutes based on 51 single chip microcomputer

2. Button control hour-minute adjustment

3. Can realize the function of full-time timing (buzzer sounds)

4. Alarm mode

5. Press the button to switch modes (Mode 1: hour-minute display, Mode 2: 60-second countdown)

1. Design ideas:

main body:

The mod value is controlled by external interrupt 0; mod=0, 1.2, 3 correspond to clock mode, adjustment mode, alarm setting mode, and one-minute countdown mode respectively.

detail:

mod0

Through the timing counter, the variable second (s) is increased every second. Every 60 seconds, 1 minute (min) is increased and s is set to 0. Every 60 minutes, 1 hour h is increased. When h>23, h=0; a one-day cycle is performed.

mod1

Key control adds min, h and s to 0

mod2

In addition, set the variables min1 and h1. When min=min1, h=h1, the buzzer will sound.

mod3

Set the variable daojishi=60, through the timing counter, daojishi decreases by 1 every second, when daojishi<0, the buzzer sounds

in addition:

1. Set external interrupt 2 and turn off the buzzer

2. Time can only send one bit at a time

program:

#include

//After K1, K3 adds minutes, K4 adds time, K2 adds seconds, K1 enters alarm setting, K2 exits

//K2 turns off the alarm

typedef unsigned int u16; //declare and define the data type

typedef unsigned char u8;

#define data8b P1

sbit K1=P3^2; //External interrupt 0

sbit K2=P3^3; //External interrupt 1

sbit K3=P3^0;

sbit K4=P3^1;

sbit BUZ=P2^4; //Buzzer, 0 beeps

sbit RW=P2^5; //Pin 4, data (1) or command (0)

sbit RS=P2^6; //Pin 5, read (1) write (0)

sbit E=P2^7; //pin 6, enable signal

u8 code dat1[]={0X30,0X31,0X32,0X33,

                               0X34,0X35,0X36,0X37,

                               0X38,0X39};

void delay(u16 i) //delay function

{

while(i--);

}

void open012() //Open interrupt 0,1, timer interrupt 0

{

TMOD|=0X01; //Select timer 0 mode, working mode 1

ET0=1; //Enable timer 0 interrupt

EA=1; //Open the general interrupt

TR0=1; //Turn on the timer

EX0=1; //Open external interrupt 0

IT0=1; //Edge trigger mode

EX1=1; //Open external interrupt 1

IT1=1; //Edge trigger

}

void wrm(u8 dat) //write command

{

delay(1000);

RS=0;

RW=0;

E=0;

data8b=dat;

E=1;

delay(1000);

E=0;

}

void wrd(u8 dat) //write data

{

delay(1000);

RS=1;

RW=0;

E=0;

data8b=dat;

E=1;

delay(1000);

E=0;

}

void zero()

{

wrm(0X38); //8-bit data, two lines display, 5*7

wrm(0X0c); //No cursor, turn on display

wrm(0X06); //Move the cursor right, but the screen does not move

wrm(0X01); //Clear screen

wrm(0X80); //Set the data pointer starting point

}

u8 fg=0,sg=0,bfg=0,bsg=0;

u16 i=0;

u8 s=0;

u8 mod=0;

char dingshi;

bit bell=0;

bit zanting=1;

void fangsong()

{

  wrd(dat1[sg/10]); //tens digit of the hour

wrd(dat1[sg%10]); //Hour digit

wrd(0x3A); //:

wrd(dat1[fg/10]); //ten digits

wrd(dat1[fg%10]); //dividing into units

wrd(0x3A); //:

wrd(dat1[(s/10)]); //10 seconds

wrd(dat1[(s%10)]); //seconds

}

void fangsong1()

{

wrm(0X80);   

  wrd(dat1[sg/10]); //tens digit of the hour

wrd(dat1[sg%10]); //Hour digit

wrd(0x3A); //:

wrd(dat1[fg/10]); //ten digits

wrd(dat1[fg%10]); //dividing into units

wrd(0x3A); //:

wrd(dat1[(s/10)]); //10 seconds

wrd(dat1[(s%10)]); //seconds

}

void chuli()

{

if(fg==60)

{

sg++;

fg=0;

}

if(sg==24)

{

sg=0;

}

}

void main()

{

u8 shijian;

open012();

zero();

chuli();

fangsong();

shijian=100;

while(1)

{

while(mod==0)

{

EX1=1; //Open external interrupt 1

if(s==60)

{

fg++; //Convert 60 seconds to 1 minute

s=0;

}

chuli();

if((fg==0)&&(shijian!=sg))

{

  BUZ=0;

shijian=sg;

}

fangsong1();

if((BUZ==0)&&(bell==0))

  {

delay(1000);

BUZ=1;

  }

if((fg==bfg)&&(sg==bsg)&&(bell==1))

BUZ=0;

else BUZ=1;

}

while(mod==1)

{

EX1=0; //Disable external interrupt 1

zero();

    fangsong();

if(K3==0)

  {

  delay(1000);

  if(K3==0)

  fg++;

   }

if(K4==0)

   {

  delay(1000);

  if(K4==0)

sg++;

   }

if(K2==0)

   {

  delay(1000);

  if(K2==0)

s=0;

   }

if(fg>59)

{

fg=0;

}

  if(sg>23)

{

sg=0;

}

if(s>=59)

{

s=0;

}

     }

while(mod==2) //Set the alarm

{

    if(bfg==60)

    {

    bsg++;

    bsg=0;

    }

    if(bsg==24)

    {

     bsg=0;

     }

    zero();

wrd(0x20);

wrd(0x20);

wrd(0x20);

  wrd(dat1[(bsg/10)]); //tens digit of the hour

    wrd(dat1[(bsg%10)]); //Hour digit

    wrd(0x3A); //:

    wrd(dat1[(bfg/10)]); //ten digits

    wrd(dat1[(bfg%10)]); //divide into units

if(K3==0)

{

delay(1000);

if(K3==0)

bfg++;

}

if(K4==0)

{

delay(1000);

if(K4==0)

bsg++;

}

bell=1;

zero();

}

while(mod==3)

{

while(zanting)

{

dingshi=60;

EX1=1; //Open external interrupt 1

wrm(0X80);   

wrd(dat1[(dingshi/10)]); //Tens digit of the hour

wrd(dat1[(dingshi%10)]); //Hour digit

   }

   wrm(0X80);   

wrd(dat1[(dingshi/10)]); //Tens digit of the hour

wrd(dat1[(dingshi%10)]); //Hour digit

while(dingshi<0)

{

wrm(0X80);   

wrd(dat1[0]); //tens digit of the hour

   wrd(dat1[0]); //Hour digit

BUZ=0;

}

}

}

}

void time0() interrupt 1

{

   TH0=0XFC; //Assign initial value to the timer, set the timer to 1ms

TL0=0X18;

i++;

if(i==1000) //ms converted to s

{

i=0;

s++;

dingshi--;

}

}

void key1() interrupt 0 //External interrupt 0, adjust time

{

delay(1000);

if(K1==0)

  { 

  mod++;

while(!K1);

  }

if(mod>3)

{

mod=0;

}

zero();

}

void naozhong() interrupt 2 //Switch the alarm

{

if(K2==0)

{

delay(1000); //debounce

if(K2==0)

{

bell=0;

BUZ=1;

zanting=~zanting;

} //Turn off the buzzer

while(!K2); //Confirm button is released

     }

}

2. Harvest

1. Become more proficient in the use of timer interrupts and external interrupts

The same button can be used to achieve different functions by turning on and off external interrupts.

2. Learn a little bit about register operations

3. Summary of Interrupt Configuration

External Interrupt

Timer interrupt

Serial communication

4. Be more proficient in using Proteus

Made a small software development version

5. Learned how to learn a new component (LCD1602)

1. Read the instructions, focusing on the timing diagram, truth table, etc.

2. Write the program according to the timing diagram

3. When neither of the above two conditions is true, look for relevant information

6. Download Principle

The principle of microcontroller programming:

Microcontroller burning, also known as microcontroller program downloading and burning, is essentially the microcontroller and PC transferring the compiled program to the microcontroller through the interface specified by the chip manufacturer according to the programming protocol specified by the chip manufacturer, and the microcontroller stores the data in its own memory.

To understand this principle, you need to know several knowledge points:

There are programs inside the MCU, which are fixed in the hardware when it leaves the factory and cannot be modified by the user (this will also be considered as no programs inside it). These programs can call various communication interfaces, internal memory, etc.

Downloadable communication interfaces: JTAG, SPI, UART, USB, etc. (There are also many that can be expanded to 485, Ethernet, etc.)

Programming protocol: Generally, it will be made public by major manufacturers and can be found in the chip's dedicated technical manual;

Memory: There are many types, such as mask, EPROM, EEROM, flash, etc., with different lifespans. Mask can only be used once and must be made by the factory. Flash can be erased and written 10,000 times or more.

It can be understood metaphorically like this: the microcontroller is the motherboard of the computer, the program we write is the operating system, the basic program for booting the operating system is loaded into the motherboard, and downloading the program is like installing the system on the computer!

7. Others

1. Understand the operating principles of current electronic watches

2. Learn to use ready-made products (spreadsheets) as references to write programs

3. Understand the importance of communicating with others (inspired by Wang, improved the original program)

3. Later plans

1. Continue to study 32

2. Practice welding skills

3. Continue to learn other peripherals of 51

4. Learn circuits, analog electronics, digital electronics, DXP ​​and other related knowledge according to your interests