Bom dia galera. Estou precisando d uma ajuda na programaçao de um irrigador q estou fazendo para um trabalho, o problema e q o lcd q estou usando (lcd 20x4 QC2004A) ele  nao liga perfeitamente aparece as linhas q mandei usar mas nao escreve. Se alguem me ajudar na programação ficarei muito grato .

*/

// libraries definition
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include "RTClib.h"

// frequency musical notes
#define NOTE_C6 1047
#define NOTE_C3 131
#define NOTE_G3 196

// pins definition
int levelSensorPin = 0;
int moistureSensorPin = 1;
int audioPin = 2;
int soggyLEDPin = 3;
int moistsoilLEDPin = 4;
int drysoilLEDPin = 5;
int pumpLEDPin = 6;
int pumpPin = 7;

// variables
int levelSensorValue; // stores the level sensor values
int moistureSensorValue; // stores the moisture sensor values
int j = 0;

// system messages
const char *string_table[] =
{
" Welcome! =)",
" Tank LOW level",
" Dry soil",
" Moist soil",
" Soggy soil",
"The water pump is on",
" ArduinoByMyself",
" Watering System",
" Please wait!"
};

// objects definition
RTC_DS1307 RTC;
LiquidCrystal_I2C lcd(0x27,20,4);

void setup(){
// serial initialization
Serial.begin(9600);

// LCD initialization
lcd.init();
lcd.backlight(); // with Backlight
lcd.clear(); // clearscreen

// Wire initialization
Wire.begin();

// RTC initialization
RTC.begin();
if (!RTC.isrunning()){
// date and time adjust as the PC computer date and time
RTC.adjust(DateTime(__DATE__, __TIME__));
}

// Arduino pins initalization
pinMode(audioPin, OUTPUT);
pinMode(soggyLEDPin, OUTPUT);
pinMode(moistsoilLEDPin,OUTPUT);
pinMode(drysoilLEDPin,OUTPUT);
pinMode(pumpLEDPin,OUTPUT);
pinMode(pumpPin,OUTPUT);

// LCD initial messages
lcd.clear();
lcd.setCursor(0,0);
lcd.print(string_table[6]);
lcd.setCursor(0,1);
lcd.print(string_table[7]);
lcd.setCursor(0,3);
lcd.print(string_table[0]);
// initialization delay
delay(5000);
}

void loop(){


// RTC parameters definition
DateTime myRTC = RTC.now();
int H = myRTC.hour();
int M = myRTC.minute();
int S = myRTC.second();

// call Clock Function
//RightHour();

// reads the sensors
levelSensorValue = analogRead(levelSensorPin);
moistureSensorValue = analogRead(moistureSensorPin);

// if low water level: plays the low level alarm
if(levelSensorValue > 600){
// system messages
lcd.clear();
RightHour();
lcd.setCursor(0,3);
lcd.print(string_table[1]);
// plays the alarm sound
for(int i=0;i<2;i++){
tone(audioPin, NOTE_G3, 200);
delay(200);
tone(audioPin, NOTE_C3, 200);
delay(200);
noTone(audioPin);
}
}

// check the moisture range
if(moistureSensorValue >= 700){
// in case of dry soil:
// system messages
lcd.clear();
RightHour();
lcd.setCursor(0,3);
lcd.print(string_table[2]);
// lights up the correct LED
digitalWrite(drysoilLEDPin,HIGH);
digitalWrite(moistsoilLEDPin,LOW);
digitalWrite(soggyLEDPin,LOW);
// plays the alarm sound
tone(audioPin, NOTE_C6, 100);
delay(250);
noTone(audioPin);
}
if((moistureSensorValue < 700) && (moistureSensorValue >= 300)){
// in case of moist soil:
// system messages
lcd.clear();
RightHour();
lcd.setCursor(0,3);
lcd.print(string_table[3]);
// lights up the correct LED
digitalWrite(drysoilLEDPin,LOW);
digitalWrite(moistsoilLEDPin,HIGH);
digitalWrite(soggyLEDPin,LOW);
delay(250);
}
if(moistureSensorValue < 300){
// in case of soggy soil:
// system messages
lcd.clear();
RightHour();
lcd.setCursor(0,3);
lcd.print(string_table[4]);
// lights up the correct LED
digitalWrite(drysoilLEDPin,LOW);
digitalWrite(moistsoilLEDPin,LOW);
digitalWrite(soggyLEDPin,HIGH);
delay(100);
}

// if the soil is dry and if it is the right time: turn on the pump for 1 minute
if((H == 16) && (M == 50) && (S == 00)){
while(moistureSensorValue >= 700){
// system messages
lcd.clear();
RightHour();
lcd.setCursor(0,1);
lcd.print(string_table[8]);
lcd.setCursor(0,3);
lcd.print(string_table[5]);
// turn the pump on
digitalWrite(pumpPin,HIGH);
digitalWrite(pumpLEDPin,HIGH);
delay(10000);
// if the soil is not moist so far
// reads the moisture sensor once more
moistureSensorValue = analogRead(moistureSensorPin);
}
// turn the pump off
digitalWrite(pumpPin,LOW);
digitalWrite(pumpLEDPin,LOW);
}

}

// Real Time Clock Function
void RightHour()
{
DateTime Now = RTC.now();
String clock_date = " Date: ";
String clock_hour = " Time: ";

int _day = Now.day();
int _month = Now.month();
int _year = Now.year();

clock_date += fixZero(_day);
clock_date += "/";
clock_date += fixZero(_month);
clock_date += "/";
clock_date += _year;

int _hour = Now.hour();
int _minute = Now.minute();
int _second = Now.second();

clock_hour += fixZero(_hour);
clock_hour += ":";
clock_hour += fixZero(_minute);
clock_hour += ":";
clock_hour += fixZero(_second);

lcd.clear();
lcd.setCursor(0, 0);
lcd.print(clock_date);
lcd.setCursor(0, 1);
lcd.print(clock_hour);

delay(500);
}

String fixZero(int i)
{
String ret;
if (i < 10) ret += "0";
ret += i;
return ret;
}