SENSORS/ACTUATORS

INTERNET OF THING (IoT)

Arduino Nano ESP32 - Ethernet

Arduino Nano ESP32 - Temperature Humidity Sensor

This tutorial provides instructions on how to use Arduino Nano ESP32 to read temperature and humidity value from DHT11 or DHT22 sensors, and print it to Serial Monitor.

Hardware Preparation

1	×	Arduino Nano ESP32
1	×	USB Cable Type-C
1	×	DHT11 Temperature Humidity Sensor Module
1	×	DHT11 Temperature Humidity Sensor Module (short)
1	×	(Optional) Temperature and Humidity Sensor DHT22
1	×	10 kΩ resistor
1	×	Breadboard
1	×	Jumper Wires
1	×	(Optional) DC Power Jack
1	×	(Recommended) Screw Terminal Expansion Board for Arduino Nano
1	×	(Recommended) Breakout Expansion Board for Arduino Nano

Or you can buy the following sensor kits:

1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables.

Overview of DHT11 and DHT22 Temperature and Humidity Sensor

In short, the DHT22 sensor is a more accurate, larger range but more expensive than DHT11. Let's see the common and differences between them

The commons

The same pinout
The same wiring to Arduino Nano ESP32
The similar Arduino Nano ESP32 code

The differences

The below table show the detaied differences between DHT11 and DHT22:

	DHT22	DHT11
The price	low cost	ultra low cost
The humidity range	0% to 100%	20% to 80%
The humidity accuracy	± 2% to 5%	5%
The temperature range	-40°C to 80°C	0°C to 50°C
The temperature accuracy	± 0.5°C	± 2°C
The reading rate	0.5Hz (one time per 2 seconds)	1Hz (one time per second)
Dimension	15.1mm x 25mm x 7.7mm	15.5mm x 12mm x 5.5mm
Operating Voltage	3 to 5V	3 to 5V

DHT11 and DHT22 Pinout

DHT11 and DHT22 sensor includes 4 pins:

GND pin: connect this pin to GND (0V)
VCC pin: connect this pin to VCC (3.3V or 5V)
DATA pin: the pin is used to communicate between the sensor and Arduino Nano ESP32
NC pin: Not connected

DHT11 and DHT22 temperature and humidity sensor Pinout

We highily recommend you using DHT11 and DHT22 sensor modules. The modules have a built-in resistor and have only three pin: VCC, GND, and DATA pins (or alternatively: +, -, and OUT pins).

DHT11 and DHT22 temperature and humidity module Pinout

image source: diyables.io

The pins order on the module's can be different between manufacturers. Please check the pin labels printed on the module carefully.

Wiring Diagram between DHT11/DHT22 and Arduino Nano ESP32

Wiring to Arduino Nano ESP32 is the same for both sensors. In orginal form, A resistor from 5K to 10K Ohms is required to keep the data line high and in order to enable the communication between the sensor and the Arduino Nano ESP32

Arduino Nano ESP32 - DHT11 Sensor Wiring

The wiring diagram between Arduino Nano ESP32 and DHT11 Temperature and humidity Sensor

This image is created using Fritzing. Click to enlarge image

Arduino Nano ESP32 - DHT22 Sensor Wiring

The wiring diagram between Arduino Nano ESP32 and DHT22 Temperature and humidity Sensor

This image is created using Fritzing. Click to enlarge image

Arduino Nano ESP32 - DHT11 Module Wiring

Most of DHT22 sensor modules have a built-in resistor, so you don't need to add it. it saves us some wiring or soldering works.

The wiring diagram between Arduino Nano ESP32 and DHT11 Temperature and humidity Module

This image is created using Fritzing. Click to enlarge image

Arduino Nano ESP32 - DHT22 Module Wiring

Most of DHT22 sensor modules have a built-in resistor, so you don't need to add it. it saves us some wiring or soldering works.

The wiring diagram between Arduino Nano ESP32 and DHT22 Temperature and humidity Module

This image is created using Fritzing. Click to enlarge image

Arduino Nano ESP32 Code - DHT11

/* * This Arduino Nano ESP32 code was developed by newbiely.com * * This Arduino Nano ESP32 code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano-esp32/arduino-nano-esp32-temperature-humidity-sensor */ #include <DHT.h> #define DHT_SENSOR_PIN D3 // The Arduino Nano ESP32 pin D31 connected to DHT11 sensor #define DHT_SENSOR_TYPE DHT11 DHT dht_sensor(DHT_SENSOR_PIN, DHT_SENSOR_TYPE); void setup() { Serial.begin(9600); dht_sensor.begin(); // initialize the DHT sensor } void loop() { // read humidity float humi = dht_sensor.readHumidity(); // read temperature in Celsius float temperature_C = dht_sensor.readTemperature(); // read temperature in Fahrenheit float temperature_F = dht_sensor.readTemperature(true); // check whether the reading is successful or not if ( isnan(temperature_C) || isnan(temperature_F) || isnan(humi)) { Serial.println("Failed to read from DHT sensor!"); } else { Serial.print("Humidity: "); Serial.print(humi); Serial.print("%"); Serial.print(" | "); Serial.print("Temperature: "); Serial.print(temperature_C); Serial.print("°C ~ "); Serial.print(temperature_F); Serial.println("°F"); } // wait a 2 seconds between readings delay(2000); }

Arduino Nano ESP32 Code - DHT22

/* * This Arduino Nano ESP32 code was developed by newbiely.com * * This Arduino Nano ESP32 code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano-esp32/arduino-nano-esp32-temperature-humidity-sensor */ #include <DHT.h> #define DHT_SENSOR_PIN D3 // The Arduino Nano ESP32 pin D31 connected to DHT22 sensor #define DHT_SENSOR_TYPE DHT22 DHT dht_sensor(DHT_SENSOR_PIN, DHT_SENSOR_TYPE); void setup() { Serial.begin(9600); dht_sensor.begin(); // initialize the DHT sensor } void loop() { // read humidity float humi = dht_sensor.readHumidity(); // read temperature in Celsius float temperature_C = dht_sensor.readTemperature(); // read temperature in Fahrenheit float temperature_F = dht_sensor.readTemperature(true); // check whether the reading is successful or not if ( isnan(temperature_C) || isnan(temperature_F) || isnan(humi)) { Serial.println("Failed to read from DHT sensor!"); } else { Serial.print("Humidity: "); Serial.print(humi); Serial.print("%"); Serial.print(" | "); Serial.print("Temperature: "); Serial.print(temperature_C); Serial.print("°C ~ "); Serial.print(temperature_F); Serial.println("°F"); } // wait a 2 seconds between readings delay(2000); }

Two above codes have only one line different.

Detailed Instructions

To get started with Arduino Nano ESP32, follow these steps:

If you are new to Arduino Nano ESP32, refer to the tutorial on how to set up the environment for Arduino Nano ESP32 in the Arduino IDE.
Wire the components according to the provided diagram.
Connect the Arduino Nano ESP32 board to your computer using a USB cable.
Launch the Arduino IDE on your computer.
Select the Arduino Nano ESP32 board and its corresponding COM port.
Open the Library Manager by clicking on the Library Manager icon on the left navigation bar of Arduino IDE
Type “Adafruit DHT” on the search box, then look for the DHT sensor library by Adafruit
Install the library by clicking on Install button.

A windows may appear to ask you to install dependencies for the library
Install all dependencies for the library by clicking on Install All button.

Arduino Nano ESP32 Adafruit Unified sensor library

Copy one of the above code and open with Arduino IDE
Compile and upload code to Arduino Nano ESP32 board by clicking Upload button on Arduino IDE
Make the sensor colder or hotter. For example, putting the sensor near a hot cup of coffee
Check out the result on the Serial Monitor. It looks like the below:.

COM6

Send

Humidity: 31.00% | Temperature: 27.00°C ~ 80.60°F Humidity: 31.00% | Temperature: 27.00°C ~ 80.60°F Humidity: 31.00% | Temperature: 27.00°C ~ 80.60°F Humidity: 31.00% | Temperature: 27.00°C ~ 80.60°F Humidity: 31.00% | Temperature: 28.00°C ~ 82.40°F Humidity: 31.00% | Temperature: 28.00°C ~ 82.40°F Humidity: 31.00% | Temperature: 28.00°C ~ 82.40°F Humidity: 31.00% | Temperature: 28.00°C ~ 82.40°F Humidity: 32.00% | Temperature: 28.00°C ~ 82.40°F Humidity: 31.00% | Temperature: 29.00°C ~ 84.20°F Humidity: 32.00% | Temperature: 29.00°C ~ 84.20°F Humidity: 31.00% | Temperature: 29.00°C ~ 84.20°F

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