LCD based digital alarm clock with digital thermometer using 8051 microcontroller (AT89C51)

This project works as a digital clock wherein a user can also set alarm. Additionally, it also works as a digital thermometer to specify the ambient temperature. Both, the clock and temperature are displayed on a 16x2 LCD screen using the 8051 microcontroller (AT89C51). AT89C51 is an eight bit controller which belongs to the 8051 family of microcontrolers.

This project incorporates the functionality of a digital clock and a digital thermometer. The digital clock works in 12 hour mode and is configured by programming the 8051 microcontroller (AT89C51). The program uses a delay function for producing a delay of 1 second. The clock and alarm times can be set through a set of external tactile switches.

The digital thermometer employs a temperature sensor LM35. The sensor responds to the temperature change by giving varying output. These analog signals of LM35 are converted to digital equivalent by ADC0804. The reference voltage (Vref) should be set properly corresponding to the desired temperature range. The data bits are taken as input by the microcontroller at port P0. The microcontroller AT89C51 also gives control signals to ADC0804.

C Code:

// Program to make a digital clock with integrated Alarm and digital thermometer

#include<reg51.h>

#define port P1

#define adc_input P0

#define cont_port P3

#define dataport P2

#define m_sec 10

sbit rs = cont_port^0;

sbit rw = cont_port^1;

sbit en = cont_port^6;

sbit dig_hr1=port^0;

sbit dig_min1=port^1;

sbit start=port^2;

sbit am_pm=port^3;

sbit alarm_set=port^4;

sbit alarm=port^7;

sbit wr= P3^2;

sbit rd= P3^3;

sbit intr= P3^4;

int hr ,hr1=0,alarm_hr=0;

int min,min1=0,alarm_min=0;

int sec,sec1=0,dig_am_pm=0,alarm_am_pm=0;

int test_final=0,test_intermediate1[10],test_intermediate2[3]={0,0,0};

void delay(unsigned int msec) // Time dealy function

{

int i,j ;

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

  for(j=0;j<1275;j++);

}

void lcd_cmd(unsigned char item)  //Function to send command to LCD           

{

dataport = item;

rs= 0;

rw=0;

en=1;

delay(1);

en=0;

return;

}

void lcd_data(unsigned char item) // Function to send data to LCD

{

dataport = item;

rs= 1;

rw=0;

en=1;

delay(1);

en=0;

return;

}

void lcd_data_string(unsigned char *str) // Function to send string to LCD

{

int i=0;

while(str[i]!='\0')

{

  lcd_data(str[i]);

  i++;

  delay(1);

}

return;

}

lcd_data_int(int time_val)  // Function to send number to LCD

{

int int_amt;

int_amt=time_val/10;

lcd_data(int_amt+48);

int_amt=time_val%10;

lcd_data(int_amt+48);

}

void lcd(unsigned char str1[10])

{

lcd_cmd(0x38);

lcd_cmd(0x0e);

delay(1);

lcd_data_string(str1);

}

void shape()  // Function to create the shape of degree

{

lcd_cmd(64);

lcd_data(2);

lcd_data(5);

lcd_data(2);

lcd_data(0);

lcd_data(0);

lcd_data(0);

lcd_data(0);

lcd_data(0);

}

void convert()  // Function to convert the data of ADC

{

int s;

s=test_final/100;

test_final=test_final%100;

lcd_cmd(0xc9);

if(s!=0)

lcd_data(s+48);

else

lcd_cmd(0x06);

s=test_final/10;

test_final=test_final%10;

lcd_data(s+48);

lcd_data(test_final+48);

lcd_data(0);

lcd_data('C');

lcd_data(' ');

delay(2);

}

void set_hr1()  // Function to set set hours digit of clock

{

hr1++;

if(hr1>11)

hr1=0;

lcd_cmd(0xc3);

lcd_data_int(hr1);

lcd_data(':');

}

void set_min1()  // Function to set set minutes digit of clock

{

min1++;

if(min1>59)

min1=0;

lcd_cmd(0xc6);

lcd_data_int(min1);

}

void set_alarm_hr1() // Function to set set hours digit of alarm

{

alarm_hr++;

if(alarm_hr>11)

alarm_hr=0;

lcd_cmd(0xc3);

lcd_data_int(alarm_hr);

lcd_data(':');

}

void set_alarm_min1() // Function to set set minutes digit of clock

{

alarm_min++;

if(alarm_min>59)

alarm_min=0;

lcd_cmd(0xc6);

lcd_data_int(alarm_min);

}

void alarm_check()  // Function to check alarm

{

if(hr==alarm_hr)

{

  if(min==alarm_min)

  {

   if(dig_am_pm==alarm_am_pm)

   {

    alarm=1;

    lcd_cmd(0x8b);

    lcd("ALARM");

   }

  }

}

}

void temp() // Function to calculate temperature

{

int i;

for(i=0;i<10;i++)

{

  delay(1);

  rd=1;

  wr=0;

  delay(1);

  wr=1;

  while(intr==1);

  rd=0;

  lcd_cmd(0x88);

  test_intermediate1[i]=adc_input/10;

  delay(1);

  intr=1;

}

for(i=0;i<10;i++)

test_intermediate2[0]=test_intermediate1[i]+test_intermediate2[0];

for(i=0;i<10;i++)

{

  delay(1);

  rd=1;

  wr=0;

  delay(1);

  wr=1;

  while(intr==1);

  rd=0;

  lcd_cmd(0x88);

  test_intermediate1[i]=adc_input/10;

  delay(1);

  intr=1;

}

for(i=0;i<10;i++)

test_intermediate2[1]=test_intermediate1[i]+test_intermediate2[1];

for(i=0;i<10;i++)

{

  delay(1);

  rd=1;

  wr=0;

  delay(1);

  wr=1;

  while(intr==1);

  rd=0;

  lcd_cmd(0x88);

  test_intermediate1[i]=adc_input/10;

  delay(1);

  intr=1;

}

for(i=0;i<10;i++)

test_intermediate2[2]=test_intermediate1[i]+test_intermediate2[2];

test_intermediate2[0]=test_intermediate2[0]/3;

test_intermediate2[1]=test_intermediate2[1]/3;

test_intermediate2[2]=test_intermediate2[2]/3;

test_final=test_intermediate2[0]+test_intermediate2[1]+test_intermediate2[2];

shape();

convert();

}

void main()

{

int k;

start=1;

dig_hr1=1;

dig_min1=1;

alarm_set=1;

alarm=0;

lcd_cmd(0x83);

lcd("SET ALARM");

lcd_cmd(0xc3);

lcd_data_int(hr1);

lcd_data(':');

lcd_data_int(min1);

while(alarm_set==0)

{

  delay(10);

  if(dig_hr1==0)

  set_alarm_hr1();

  if(dig_min1==0)

  set_alarm_min1();

}

if(am_pm==0)

{

  lcd_cmd(0xc8);

  lcd_data_string("am");

  alarm_am_pm=0;

}

if(am_pm==1)

{

  lcd_cmd(0xc8);

  lcd_data_string("pm");

  alarm_am_pm=1;

}

delay(200);

lcd_cmd(0x01);

lcd_cmd(0x83);

lcd("SET TIMING");

lcd_cmd(0xc3);

lcd_data_int(hr1);

lcd_data(':');

lcd_data_int(min1);

while(start==0)

{

  delay(10);

  if(dig_hr1==0)

  set_hr1();

  if(dig_min1==0)

  set_min1();

}

if(am_pm==0)

{

  lcd_cmd(0xc8);

  lcd_data_string("am");

  dig_am_pm=0;

}

if(am_pm==1)

{

  lcd_cmd(0xc8);

  lcd_data_string("pm");

  dig_am_pm=1;

}

delay(200);

lcd_cmd(0x01);

while(1)

{

  for(k=0;k<2;k++)

  {

   for(hr=hr1;hr<12;hr++)

   {

    for(min=min1;min<60;min++)

    {

     for(sec=0;sec<60;sec++)

     {

      lcd_cmd(0x81);

      delay(1);

      lcd_data_int(hr);

      lcd_data(':');

      lcd_data_int(min);

      lcd_data(':');

      lcd_data_int(sec);

      if(dig_am_pm==0)

      {

       lcd("am");

      }

      else

      {

       lcd("pm");

      }

      alarm_check();

      lcd_cmd(0xc3);

      delay(2);

      lcd_data_string("TEMP:");

      temp();

      lcd_data_string("    ");

     }

    }

   min1=0;

   }

  if(dig_am_pm==0)

  dig_am_pm=1;

  else

  dig_am_pm=0;

  hr1=0;

  }

}

}