How to Make a humidity and temperature meter using Arduino and LCD

Components Required

• Arduino Uno:
  
• 16x2 LCD Display:
  
• DHT11 Sensor
  
• 10K Preset
  

DHT-11 module

This module is used to measure humidity and temperature of surrounding. It comprises a thermistor and a capacitive humidity plates to measure temperature and humidity.

Features

• Temperature Range: 0°C to 50°C (±2°C accuracy)
• Humidity Range: 20% to 90% RH (±5% accuracy)
• Operating Voltage: 3V – 5V
• Current Consumption: ~2.5mA (during measurement)
• Sampling Rate: 1 reading per second (1 Hz)
• Interface: Single-wire digital output (not analog)

Pinouts

• 1. + or VCC → Power supply (3.3V – 5V)
• 2. DATA → Digital signal output
• 3. - or GND → Ground

DHT11 connection with Arduino

• 1. Connect + terminal of DHT-11 to 5volts of Arduino.
• 2. Connect - terminal of DHT-11 to GND of Arduino.
• 3. Connect OUT terminal of DHT-11 to A0 pin of Arduino.

About 16x2 LCD Display

The name "16x2 LCD display" comes from the fact that it has 16 columns and 2 rows, meaning we can display 32 characters on this screen. Characters can be alphabets, numbers, or custom-made characters. Each column is made from a 5x8 matrix of pixels (40 pixels per column).

• Operating voltage: 4.7V to 5.3V
• Current consumption: 1mA without backlight
• Alphanumeric display: can show alphabets and numbers
• Works in both 8-bit and 4-bit mode
• Available in Green and Blue backlight

Pinouts

• 1. Vss: Connect to GND
• 2. Vdd: +5V (4.7V–5.3V)
• 3. VEE: Contrast adjustment
• 4. RS: Command/data register
• 5. R/W: Normally GND (write mode)
• 6. Enable: Activates read/write
• 7. Data bit 0:- To microcontroller to send 8 bit data
• 8. Data bit 1:- To microcontroller to send 8 bit data
• 9. Data bit 2:- To microcontroller to send 8 bit data
• 10. Data bit 3:- To microcontroller to send 8 bit data
• 11. Data bit 4:- To microcontroller to send 4/8 bit data
• 12. Data bit 5:- To microcontroller to send 4/8 bit data
• 13. Data bit 6:- To microcontroller to send 4/8 bit data
• 14. Data bit 7:- To microcontroller to send 4/8 bit data
• 15. LED+: Backlight
• 16. LED-: Backlight

16x2 LCD conenction with Arduino

• 1. VSS and LED- pin of LCD are combined together and are grounded.
• 2. VCC and LED+ pin of LCD are combined together and is connected to 5v pin of Arduino.
• 3. Then connect a Preset to VEE to adjust the contrast of LCD by varying the knob of Preset.
• 4. Then connect RS pin of LCD to 6th pin of Arduino and R/W pin of LCD to 7th pin of Arduino.
• 5. Then connect E pin of LCD to 8th pin of Arduino.
• 6. Then connect DB4 pin of LCD to 9th pin of Arduino, DB5 pin to 10th pin , DB6 pin to 11th pin and DB7 to 12th pin of Arduino.
• 7. Connect 1 terminal of toggle switch to 5 V and it's other terminal to A0 pin.

Circuit Diagram

Arduino Code

#include <LiquidCrystal.h >
#include "DHT.h"
DHT dht(A0, DHT11);
LiquidCrystal lcd(6,7,8,9,10,11,12);
float humidity,celcius,fahrenheit;
void setup() 
{

  lcd.begin(16,2);

  dht.begin();

}
void loop() 
{
  delay(2000);

  lcd.clear();

  humidity = dht.readHumidity();

  celcius = dht.readTemperature();

  lcd.print("Humidity:");

  lcd.print(humidity);

  lcd.print("%");

  lcd.setCursor(0,1);

  lcd.print(celcius);

  lcd.print("C || ");

  fahrenheit=1.8*celcius + 32;

  lcd.print(fahrenheit);

  lcd.print("F");
}