/* Code copyright to “Circuits Bazaar” for Educational purposes .
you can’t use it for commercial
purpose */
#include<reg51.h>
#define port P1
#define dataport P2
#define key P3
#define sec 100
sbit rs = port^0;
sbit rw = port^1;
sbit en = port^2;
sbit col1=key^4;
sbit col2=key^5;
sbit col3=key^6;
sbit row1=key^0;
sbit row2=key^1;
sbit row3=key^2;
sbit row4=key^3;
sbit buzzer=P1^3;
sbit lock_output=P1^4;
sbit wrong_pass= P1^5;
sbit relay = P1^6;
int check=0;
int digit[4]={0,0,0,0};
int dig_one=4;
int dig_two=4;
int dig_three=3;
int dig_four=0;
int i,count=0;
void delay(unsigned int msec) //Time delay 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(10);
return;
}
void lcd(unsigned char str[10]) // Function to send string to LCD
lcd_cmd(0x38);
lcd_cmd(0x0e);
lcd_data_string(str);
void ans()
if(check>3)
lcd_cmd(0x01);
lcd_cmd(0x82);
lcd_data_string(" LOCK OPEN");
lock_output=1;
wrong_pass=0;
relay=~relay;
else
lcd_cmd(0x01);
lcd_cmd(0x81);
lcd_data_string("WRONG PASSWORD");
lock_output=0;
wrong_pass=1;
count++;
delay(750);
void code_check() // Function to check password
if(i<=3 )
switch((i+1))
case 1: {
if(dig_one==digit[0])
check=check+1;
break;
case 2: {
if(dig_two==digit[1])
{
check=check+1;
break;
case 3: {
if(dig_three==digit[2])
check=check+1;
break;
case 4: {
if(dig_four==digit[3])
check=check+1;
break;
if(i==3)
{
ans();
void display(int a) //Display function
switch(a)
case 1:{
lcd_data('1');
delay(30);
digit[i]=1;
code_check();
break;
case 2:{
lcd_data('2');
delay(30);
digit[i]=2;
code_check();
break;
case 3:{
lcd_data('3');
delay(30);
digit[i]=3;
code_check();
break;
case 4:{
lcd_data('4');
delay(30);
digit[i]=4;
code_check();
break;
case 5:{
lcd_data('5');
delay(30);
digit[i]=5;
code_check();
break;
case 6:{
lcd_data('6');
delay(30);
digit[i]=6;
code_check();
break;
}
case 7:{
lcd_data('7');
delay(30);
digit[i]=7;
code_check();
break;
case 8:{
lcd_data('8');
delay(30);
digit[i]=8;
code_check();
break;
case 9:{
lcd_data('9');
delay(30);
digit[i]=9;
code_check();
break;
case 0:{
lcd_data('0');
delay(30);
digit[i]=0;
code_check();
break;
void check_col1()
row1=row2=row3=row4=1;
row1=0;
if(col1==0)
display(1);
row1=1;
row2=0;
if(col1==0)
display(4);
row2=1;
row3=0;
if(col1==0)
display(7);
row3=1;
row4=0;
if(col1==0)
{
row4=1;
void check_col2()
row1=row2=row3=row4=1;
row1=0;
if(col2==0)
display(2);
row1=1;
row2=0;
if(col2==0)
display(5);
row2=1;
row3=0;
if(col2==0)
display(8);
row3=1;
row4=0;
if(col2==0)
display(0);
row4=1;
}
void check_col3()
row1=row2=row3=row4=1;
row1=0;
if(col3==0)
display(3);
row1=1;
row2=0;
if(col3==0)
display(6);
row2=1;
row3=0;
if(col3==0)
display(9);
row3=1;
row4=0;
if(col3==0)
row4=1;
void main()
{
lock_output=wrong_pass =0;
buzzer=1;
lcd_cmd(0x01);
col1=col2=col3=1;
relay=0;
lcd_cmd(0x38);
lcd_cmd(0x0C);
lcd_cmd(0x83);
lcd("WELCOME");
delay(500);
while(1)
lcd_cmd(0x01); //Clear LCD screen
lock_output=0;
wrong_pass=0;
lcd_cmd(0x81); // Set cursor on position first of first line
lcd("ENTER PASSWORD");
check=0;
row1=row2=row3=row4=0;
while(col1==1 && col2==1 && col3==1);
for(i=0;i<4;i++)
delay(100);
lcd_cmd(0xc4+i);
row1=row2=row3=row4=0;
while(col1==1 && col2==1 && col3==1);
row1=row2=row3=row4=0;
if(col1==0)
check_col1();
else
if(col2==0)
check_col2();
else
if(col3==0)
check_col3();
if(count==4)
lcd_cmd(0x01);
lcd_cmd(0x86);
lcd("SORRY");
lcd_cmd(0xc1);
lcd("NO MORE TRIALS");
buzzer=0;
while(1);
