#include<string.h>
#include<avr/io.h>

#define adc_vol(a)  (a/1023.0)*5      // for adc voltage conversion
char str[10] ;            // for string

void setup(){
  delay(55);
  Serial.begin(9600);
  
  DDRB|=(1<<DDB3)|(1<<DDB4);   // enable and rw pin
  DDRD = 0xF0;                // pins 4to 7
  lcd_initialize();
  
  setCursor(0,0);         
  lcdWrite(1,"VOL:");
}  

void loop()
  {  
    int adc1= read(0);
    double v1= adc_vol(adc1);
    setCursor(0,1);
    
    String a=String(v1,6);
    strcpy(str, a.c_str());  //to convert String to char array
    lcdWrite(1, str);
    delay(100);
  }
 /*ADC reading*/
int read(int pin)
{
  ADMUX=0x00; 
  ADMUX |= (1 << REFS0)|pin;    //setting channel

  ADCSRA=0x00;  
  ADCSRA |= (1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0);
  ADCSRA |= (1 << ADEN);  //to enable ADC
  ADCSRA |= (1 << ADSC);    //to start ADC conversion
  while(ADCSRA & (1<<ADSC)); 
  int adc= (ADCL|(ADCH<<8));
  return adc;
}
/*LCD Command writting*/
void lcdCmdWrite (int select,char data)
{
    if (select==1)            //0- command mode   1- data mode
      PORTB|=(1<<PORTB4);
    else
      PORTB&=~(1<<PORTB4);
       
    PORTD |= (data& 0xF0); //data assigning MSB
     /*enabling */  
    PORTB|=(1<<PORTB3);
    delay(15);
    PORTB&=~(1<<PORTB3);
    delay(15);
    PORTD=0x00;            //resetting data pins
   
    PORTD |= (data& 0x0F)<<4;  //next Data assigning LSB
    /*enabling */
    PORTB|=(1<<PORTB3);
     delay(15);           //delay as per datasheet
    PORTB&=~(1<<PORTB3);
     delay(15);
    PORTD=0x00;           //resetting
    
}

void lcdWrite (int select, char data_l[16])
{
  char data;
  int len=strlen(data_l);
  for(int i=0;i<len;i++)
  {
    if(i==16)                             // next line code
      lcdCmdWrite(0,0xC0);
    data=data_l[i];                       //Passing string as character for cmd write
    lcdCmdWrite(1,data);
  }
}
/*initalize lcd*/
void lcd_initialize()
{
  lcdCmdWrite(0,0x02);    //return home
  lcdCmdWrite(0,0x28);    //4 bit mode 
  lcdCmdWrite(0,0x0C);    //display on, cursor off
  lcdCmdWrite(0,0x06);    // cursor increment
  lcdCmdWrite(0,0x01);    //clear display
}
/* setting cursor*/
void setCursor(int col, int row)    
{
   lcdCmdWrite(0, 0x80 | (col + ((row==0)?0x00:0x40)));
}