Why is my liquid crystal display not showing any output?

Question

UPDATE: The LCD will light up only when the all my components are located in the bottom right of the breadboard. Why am I not able to use the entire breadboard for my circuit?

I am trying to display data from a temperature and humidity sensor on the serial monitor and the liquid crystal display.

I am using :

• Arduino Uno R3
• I2C 16x2 LCD Module
• 3 pin DHT11 sensor

Here is my code :

#include <dht.h> // initialize the digital temperature and humidity sensor library ("DHTlib")
#include <LiquidCrystal_I2C.h> // initialize the liquid crystal display library ("LiquidCrystal I2C")
#include <Wire.h> // intialize the wire library 
/* the first parameter is the I2C address
 * the second parameter is how many columns are on your screen
 * the third parameter is how many rows are on your screen
*/
LiquidCrystal_I2C lcd(0x27, 16, 2);
dht DHT; // create a handle to call functions from the sensor library 
#define DHT11_PIN 7 // assign a digital pin number to the sensor 
float TempC; // create a variable to store temperature in celsius
float TempF; // create a variable to store temperature in fahrenheit
float Humi; // create a variable to store humidity
void setup()
{
 lcd.init(); // initialize liquid crystal display 
 lcd.backlight(); // turn on the backlight of the lcd 
 pinMode(DHT11_PIN,INPUT); // configure the pin for the sensor as an input for reading the data
 Serial.begin(9600); // set data rate in bits per second for serial data transmission 
}
void loop()
{
 // collect sensor data 
 int chk = DHT.read11(DHT11_PIN); // store sensor data in a variable
 TempC = DHT.temperature; // store temperature in Celsius
 TempF = 9 / 5 * TempC + 32; // store temperature in Fahrenheit
 Humi = DHT.humidity; // store relative humidity as a percentage
 // display sensor data on LCD 
 lcd.setCursor(0,0); //tell the screen to write on the top row
 lcd.print("T: ");
 lcd.print(TempC); // print the temperature in Celsius
// lcd.print(TempF); // print the temperature in Fahrenheit
 lcd.print((char)223); // print the degree symbol 
 lcd.print(" C"); 
// lcd.print(" F"); 
 lcd.setCursor(0,1); // tell the screen to write on the bottom row
 lcd.print("H: "); 
 lcd.print(Humi); // print the humidity
 lcd.print(" %"); 
 // display sensor data on the serial monitor 
 Serial.print("Temperature = ");
 Serial.print(TempC); // print the temperature in Celsius
// Serial.print(TempF); // print the temperature in Fahrenheit
 Serial.print("\xc2\xb0"); // print the degree symbol 
 Serial.println(" C"); 
// Serial.println(" F"); 
 Serial.print("Humidity = ");
 Serial.print(Humi); // print the humidity
 Serial.println(" %");
 delay(2000); //delay fetching the next sensor values for 2 seconds 
}

enter image description here

My jumper wires are connected as follows:

• DHT plus → red plus row
• DHT middle → digital pin 7
• DHT minus → blue minus row
• LCD GND → blue minus row
• LCD VCC → red plus row
• LCD SDA → analog pin A4
• LCD SCL → analog pin A5
• Red plus row → 5V pin
• Blue minus row → GND pin

• Dev Dhruv: Do you not see a breadboard, an arduino board, a liquid crystal display, a sensor, and jumper wires all hooked up?
• StarCat: The picture is unusable, dark and low resolution. Pin names and wire paths are not clearly visible. These allow others to try to identify your problem and it would be a good idea to put some more effort into getting them across clearly. It might also be a good idea to describe your setup in text (such as which pins are connected to which other pins).
• StarCat: Btw, it looks like there’s nothing connected to the (I2C) SDA and SCL pins on your Arduino, but it’s hard to make out. There’s also no way to see if the power pins of your LCD are properly connected.
• Dev Dhruv: All right, I put a new picture, and I explained the setup. Is there an error in my code or in my circuit?
• Michel Keijzers: Did you try moving the knob on the I2C 16x2 LCD Module for changing the contrast?

Answer 1

Your breadboard is one of those which have the power/GND lines interrupted between columns 31 and 33. I also once fell into this trap. If you look closely, you see that the blue and red lines are interrupted in the middle of the board. Just put wires between these pins to bridge the gap.

• Dev Dhruv: Thanks! I never realized my problem was so trivial!
• PMF: Glad I could help. If this answer helped you, please don't forget to accept it.