#include"I2C.h"
#include"ADC.h"
#include<string.h>
void setup()
{
   float temp;
  ADC_init();
  char str[20];
   I2C_LCD_START();                      // initialization of I2C with start condition
  I2C_LCD_SA_TRANSFER();                // slave address + write data transfered 
   LCD_init();                           //lCD initialization
  while(1){
  temp = convertToCelcius(AnalogRead());
  sprintf(str,"Temperature: %02d C",(uint16_t)temp);
   LCD_cmd(0x80);                       // init line 1 condition 
   LCD_string(str,20);          // string " Welcome To"
   I2C_LCD_STOP();
  }
}

void loop()
{
   Serial.println("V.....");
}


sketch.ino

diagram.json

#define TWINT_SET 0x80                  // setting TWINT to 1
#define TWINT_EN 0x84                   // setting TWINT to 1 and Enable in TWCR
#define START 0x08                      // status codes for start data transfer
#define MT_SLA_ACK 0x18                 // status codes for master slave ack transfer
#define MT_DATA_ACK 0x28                // status codes for master slave ack transfer
#define CR_A 0xbc                       // Control register address
#define SR_A 0xb9                       // Status register address
#define DR_A 0xbb                       // Data register address
#define START_CONDITION 0xA4            // initializion of I2C and start condition
#define STOP_CONDITION 0x94             // Stop conditon
#define SA 0x4e                         // Slave address + write
/*********************************************************************************/
// rs=p0
// r/wr =p1  in i2c
// en=p2
#define SET_en 0x0c                     // setting the enable pin p2
#define N 0x08                          // Reset the all the pins p0,p1,p2 and led+ pin p3=8
#define SET_rs 0x09                     // setting the register select pin p0
#define SET_en_rs 0x0d                  // setting the Register select pin and enable p0 and p2 // write p1=0

/*********************************************************************************/

void delay1()
{
  volatile long i;
  for(i=0;i<600;i++);
}
void ERROR()
{
  Serial.println("Error");       
}

/*********************************************************************************/

void I2C_LCD_START()                     //initiates the i2c lcd
{
   volatile char *twsr,*twcr;  
   twcr=CR_A;                            // control register address
   twsr=SR_A;                            // status register address
   *twcr=START_CONDITION;                // initialization i2c and start condition and TWI_INT is set to 1
   while(!(*twcr & TWINT_SET));          // waits until the i2c data get transferred
   if ((*twsr & 0xF8) != START)           // checking the status codes
        ERROR();
}

/*********************************************************************************/

void I2C_LCD_SA_TRANSFER()               //slave address + write
{
    volatile char *twdr,*twcr,*twsr;
   twdr=DR_A;                            // data register address
   twcr=CR_A;                            // control register address
   twsr=SR_A;                            // status register address
   *twdr=SA;                             // slave address + write
   *twcr=TWINT_EN;                       // TWI_INT is set to 1 and Enble
   while(!(*twcr & TWINT_SET));          // waits until the i2c data get transferred
   if ((*twsr & 0xF8) != MT_SLA_ACK)     // checking the status codes of Master transfer slave acknowledge
         {  ERROR(); }
}
/*********************************************************************************/

void I2C_LCD_DATA_TRANSFER(char data)    // data byte
{
   volatile char *twdr,*twcr,*twsr;
   twdr=DR_A;                            // data register address
   twcr=CR_A;                            // control register address
   twsr=SR_A;                            // status register address
   *twdr=data;                           // required data
   *twcr=TWINT_EN;                       // TWI_INT is set to 1 and enble
   while(!(*twcr & TWINT_SET));          //waits until the i2c data get transferred
   if ((*twsr & 0xF8) != MT_DATA_ACK)    // checking the status codes of Master transfer data acknowledge
          {  ERROR(); }
}

/*********************************************************************************/

void I2C_LCD_STOP()                      //initiates the i2c lcd
{
   volatile char *twsr,*twcr;  
   twcr=CR_A;                            // control register address
   twsr=SR_A;                            // status register address
   *twcr=STOP_CONDITION;                 // initialization i2c and stop condition and TWI_INT is set to 1
}

/*********************************************************************************/
                    // LCD Functions
/*********************************************************************************/

 void LCD_data(unsigned char data )
{
  volatile unsigned char data1;
   data1 = (data & 0xf0);                            // if data = 10100111 and first you have to send MSB bits 1010 so that |(OR) operation is performed so the data1=1010 0000 
   I2C_LCD_DATA_TRANSFER(data1 | SET_en_rs);         // Now send the data1 into i2c data function with MSB bits data and LSB bits for en,rs,write,led+ conditions
   delay1();                                         // delay 
   I2C_LCD_DATA_TRANSFER(data1 | SET_rs);          
   delay1();

   data1=(data << 4) & 0xf0;                         // now data = 10100111 and  you have to send LSB bits 0111 so that |(OR) and 4 bits left shift operation is performed so the data1=0111 0000 
   I2C_LCD_DATA_TRANSFER(data1 | SET_en_rs);         // Now send the data1 into i2c data function with MSB bits data and LSB bits for en,rs,write,led+ conditions
   delay1();
   I2C_LCD_DATA_TRANSFER(data1 | SET_rs);
   delay1();
}

/*************************************************************************************************/

void LCD_cmd(unsigned char data)
{
    volatile unsigned char data1;
   data1 = (data & 0xf0);
   I2C_LCD_DATA_TRANSFER(data1 | SET_en);
   delay1();
   I2C_LCD_DATA_TRANSFER(data1 | N);
   delay1();

   data1=(data << 4) & 0xf0;
    I2C_LCD_DATA_TRANSFER(data1 | SET_en);
    delay1();
   I2C_LCD_DATA_TRANSFER(data1 | N);
   delay1();
 
}

/*************************************************************************************************/

void LCD_string(char *ptr,char length)
{
 for(volatile char i=0;i<length;i++)
  {
    LCD_data(ptr[i]);
    delay1();
  }
}

/*************************************************************************************************/

void LCD_init()
{
  LCD_cmd(0x02);
  LCD_cmd(0x28);
  LCD_cmd(0x0c);
  LCD_cmd(0x06);
  LCD_cmd(0x01);
}

I2C.h

void ADC_init()
{
volatile char *admux,*adcsrb,*adcsra,*didro=0x7e;
                   admux=0x7c,adcsrb=0x7b,adcsra=0x7a;
   *admux = 0x40;         //result will be right justified
   *adcsrb = 0b00000000;  //ADC at free running mode, 0x00
   *adcsra = 0b10000111;  //0x87
   *didro=0x01;
}
unsigned short convert_16bitdata(uint16_t L,uint16_t H)
{
  uint16_t data;
  data = (H<<8) + L;
  return data;
}
unsigned short AnalogRead(void)
{
   uint8_t *adcsra=0x7a,*adcdl=0x78,*adcdh=0x79;
  volatile uint16_t data;
  *adcsra=0x40;
  while(*adcsra & 0x40);
  data = convert_16bitdata(*adcdl,*adcdh);
  return data;
}
float convertToCelcius(uint16_t analogValue)
{
  short BETA = 3950; 
    float celsius = 1 / (log(1 / (1023. / analogValue - 1)) / BETA + 1.0 / 298.15) - 273.15;
    return celsius;
}