Temperature and Humidity Monitoring Using DHT22 and ESP8266 NodeMCU

ESP8266 17-10-25

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Tutorial plan

1- Objective of the tutorial

2- The necessary components

3- ESP8266 Assembly with I2C LCD Display and DHT22 sensor

4- Program ESP8266 NodeMCU with MicroPython

Objective of the tutorial

The objective of this tutorial is to measure and display the ambient temperature and humidity using the DHT22 sensor connected to an ESP8266 NodeMCU board.

The measured values will be shown in real time on an LCD I2C screen, allowing users to easily monitor environmental conditions.

Through this project, learners will understand how to:

- interface the DHT22 sensor with the ESP8266 NodeMCU.

- read temperature and humidity data using MicroPython.

- display the sensor readings on an LCD I2C display.

The necessary components

1- ESP8266 NodeMCU Board

The ESP8266 NodeMCU Board Serves as the main microcontroller that reads data from the DHT22 sensor and displays it on the LCD.

It provides built-in Wi-Fi for potential IoT extensions (e.g., cloud data logging).

2- DHT22 Temperature and Humidity Sensor

DHT22

The DHT22 sensor Measures the ambient temperature and relative humidity.

It Offers higher accuracy and wider measurement range compared to the DHT11 sensor.

3- LCD 20x4 Display with I2C Module

The LCD 20x4 Display with I2C Module displays the measured temperature and humidity values in real time.

The I2C interface reduces wiring complexity by using only two data lines (SDA and SCL).

4- Breadboard

plaque d'essai

The Breadboard is used to easily connect components without soldering.

5- Jumper Wires

Fils de connexion

The Jumper Wires are used for making connections between the ESP8266, DHT22, and the LCD I2C module.

ESP8266 Assembly with I2C LCD Display and DHT22 sensor

Attaching the I2C LCD Display :

- connect the VCC pin of the display to VIN pin of the ESP8266

- connect the GND pin of the display to GND pin of the ESP8266

- connect the SDA pin of the display to D1 (GPIO5) pin of the ESP8266

- connect the SCL pin of the display to D2 (GPIO4) pin of the ESP8266

Mounting the DHT22 Sensor:

- connect the VCC(+) pin of the DHT22 Sensor to 3V pin of the ESP8266

- connect the GND(-) pin of the DHT22 to GND pin of the ESP8266

- connect the OUT pin of the DHT22 to D0 (GPIO16) of the ESP8266

Program ESP8266 NodeMCU with MicroPython

Here is a complete MicroPython program to read temperature and humidity using the DHT11 sensor connected to the ESP8266 NodeMCU board:

Ensure you have the necessary libraries installed: dht, 'i2c_lcd' and 'lcd_api'.

import machine
from machine import Pin, SoftI2C
from time import sleep
from lcd_api import LcdApi
from i2c_lcd import I2cLcd
import dht

I2C_ADDR = 0x27
totalRows = 4
totalColumns = 20
# === Initialisation LCD I2C ===
i2c = SoftI2C(scl=Pin(5), sda=Pin(4), freq=10000)     #initializing the I2C method for ESP8266
lcd = I2cLcd(i2c, I2C_ADDR, totalRows, totalColumns)

#lcd2 = I2cLcd(i2c, I2C_ADDR, totalRows, totalColumns)
p16=Pin(16, Pin.IN)
# DHT22 Sensor Configuration
d=dht.DHT22(p16)
lcd.clear()
while True:   
    d.measure()
    t=d.temperature() #read temperature
    h=d.humidity() #read humidity
    lcd.clear()
    lcd.move_to(0,0)
    lcd.putstr("temperature:"+str(int(t))+"C")
    lcd.move_to(0,1)
    lcd.putstr("humdidity:"+str(int(h))+"%")
    sleep(4)