waterlevel indicator LCD by using Microontroller ATMEL 89C51

1. // Program to make a Liquid level indicator using LCD
#include<reg51.h>
sbit rs=P1^0; //register select pin
sbit rw=P1^1; //read/write pin
sbit e=P1^2; //enable pin
sbit motor=P1^3;
sbit quat=P3^0; //pin connected to quater level of tank
sbit half=P3^1; //pin connected to half level of tank
sbit quat_3=P3^2; //pin connected to three -fourth level of tank
sbit full=P3^3; //pin connected to full level of tank
sbit spkr_on=P3^4;
sbit spkr_off=P3^5; // pin to off speaker
void delay(int k) //delay function
{
int i,j;
for(i=0;i<k;i++)
for(j=0;j<1275;j++);
}
void write(int j) //write function
{
rs=1; //selecting command register
rw=0; //selecting to write
P2=j; //putting value on the pins
e=1; //strobe the enable pin
delay(1);
e=0;

2. return;
}
void cmd(int j) //command function
{
P2=j; //put the value on pins
rs=0; //selecting command register
rw=0; //selecting to write
e=1; //strobe enable pin
delay(1);
e=0;
return;
}
void puts(char *a) //puts function to print a string
{
unsigned int p=0;
for(;a[p]!=0;p++)
write(a[p]);
}
void lcd_init(void) // function to initialise the LCD
{
cmd(0x38); //setting 8-bit interface, 2 lines, 5*7 Pixels
delay(1);
cmd(0x0e); //turning on underline visible cursor
delay(1);

3. cmd(0x01); //clearing screen
cmd(0x80); //moving cursor to the begining of line 1 of LCD
}
void main()
{
quat=half=quat_3=full=spkr_off=1; //configuring as input pins
quat=half=quat_3=full=spkr_off=0; //lowering input pins
spkr_on=1; // making speaker on pin high,as it works on negative logic
motor=1;
while(1)
{
while(quat==0&&half==0&&quat_3==0&&full==0&&spkr_off==0) //condition when tank is empty
{
lcd_init(); // initialising LCD
puts("VACANT"); //printing VACANT on lcd
motor=1;
delay(200);
}
while(quat==1&&half==0&&quat_3==0&&full==0&&spkr_off==0) //condition when tank is
quater
{ motor=1;
lcd_init();
puts("QUATER"); //printing QUATER on lcd
delay(200);
}
while(quat==1&&half==1&&quat_3==0&&full==0&&spkr_off==0) //condition when tank is
half

4. {
lcd_init();
puts("HALF"); //printing HALF on lcd
motor=1;
delay(200);
}
while(quat==1&&half==1&&quat_3==1&&full==0&&spkr_off==0) //condition when tank is
three-fourth
{
lcd_init();
puts("3/4 FULL"); //printing 3/4 FULL on lcd
motor=1;
delay(200);
}
while(quat==1&&half==1&&quat_3==1&&full==1&&spkr_off==0) //condition when tank is full
{
lcd_init();
puts("FULL;Motor off "); //printing FULL;CLOSE TAP on lcd
spkr_on=0;// Enabling speaker
motor =0;
delay(200);
}
while(quat==1&&half==1&&quat_3==1&&full==1&&spkr_on==0&&spkr_off==1)//enabling high
speaker_off pin
{
spkr_on=1;//disabling speaker
motor=0;

5. }
}
}