ESP32 DHT21 / AM2301A Temperature and Humidity Sensor

Code Examples

Below you can find code examples of DHT21 / AM2301A Temperature and Humidity Sensor with ESP32 in several frameworks:

• Arduino IDE
• ESP-IDF
• ESPHome
• PlatformIO
• MicroPython

ESP32 DHT21 / AM2301A Arduino IDE Code Example

Example in Arduino IDE

Fill in your main Arduino IDE sketch file with the following code to use the DHT21 / AM2301A Temperature and Humidity Sensor:

#include "DHT.h"

#define DHTPIN 4     // Digital pin connected to the DHT sensor
#define DHTTYPE DHT21   // DHT 21 (AM2301)

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(115200);
  Serial.println("DHT21 Sensor Example");

  dht.begin();
}

void loop() {
  // Wait a few seconds between measurements
  delay(2000);

  // Reading temperature or humidity takes about 250 milliseconds!
  float humidity = dht.readHumidity();
  // Read temperature as Celsius (the default)
  float temperature = dht.readTemperature();

  // Check if any reads failed and exit early (to try again).
  if (isnan(humidity) || isnan(temperature)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  Serial.print("Humidity: ");
  Serial.print(humidity);
  Serial.print(" %	");
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" °C");
}

This Arduino sketch demonstrates how to interface with the DHT21 sensor. It initializes the sensor on digital pin 4 and reads the temperature and humidity every 2 seconds. The readings are then printed to the Serial Monitor. The code includes checks to ensure that the sensor readings are valid.

Connect your ESP32 to your computer via a USB cable, Ensure the correct Board and Port are selected under Tools, Click the "Upload" button in the Arduino IDE to compile and upload the code to your ESP32.

ESP32 DHT21 / AM2301A ESP-IDF Code Example

Example in Espressif IoT Framework (ESP-IDF)

If you're using ESP-IDF to work with the DHT21 / AM2301A Temperature and Humidity Sensor, here's how you can set it up and read data from the sensor. Fill in this code in the main ESP-IDF file:

#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/gpio.h"
#include "dht.h"

#define DHT_PIN GPIO_NUM_4

void app_main() {
    setDHTgpio(DHT_PIN);

    while (1) {
        printf("Reading DHT21 sensor...\n");

        int ret = readDHT();
        errorHandler(ret);

        printf("Humidity: %.1f%%\n", getHumidity());
        printf("Temperature: %.1f°C\n", getTemperature());

        vTaskDelay(2000 / portTICK_PERIOD_MS);
    }
}

This ESP-IDF example demonstrates how to read data from the DHT21 sensor using GPIO pin 4. The `readDHT()` function reads the sensor data, and the humidity and temperature values are retrieved using `getHumidity()` and `getTemperature()` functions, respectively. The readings are printed to the console every 2 seconds.

Update the I2C pins (I2C_MASTER_SDA_IO and I2C_MASTER_SCL_IO) to match your ESP32 hardware setup, Use idf.py build to compile the project, Use idf.py flash to upload the code to your ESP32.

ESP32 DHT21 / AM2301A ESPHome Code Example

Example in ESPHome (Home Assistant)

Fill in this configuration in your ESPHome YAML configuration file (example.yml) to integrate the DHT21 / AM2301A Temperature and Humidity Sensor

sensor:
  - platform: dht
    pin: GPIO4
    model: DHT21
    temperature:
      name: "Living Room Temperature"
    humidity:
      name: "Living Room Humidity"
    update_interval: 60s

The ESPHome configuration defines the DHT21 sensor using the `dht` platform. The `pin` specifies the GPIO pin (e.g., GPIO4) where the sensor's DATA pin is connected. The `model` is set to `DHT21` to ensure correct data handling. Two sensors are configured: one for temperature and one for humidity, each with descriptive names such as 'Living Room Temperature' and 'Living Room Humidity.' The `update_interval` is set to 60 seconds, meaning the sensor will provide new data every minute.

Upload this code to your ESP32 using the ESPHome dashboard or the esphome run command.

ESP32 DHT21 / AM2301A PlatformIO Code Example

Example in PlatformIO Framework

For PlatformIO, make sure to configure the platformio.ini file with the appropriate environment and libraries, and then proceed with the code.

Configure platformio.ini

First, your platformio.ini should look like below. You might need to include some libraries as shown. Make sure to change the board to your ESP32:

[env:esp32dev]
platform = espressif32
board = esp32dev
framework = arduino
lib_deps = 
    adafruit/DHT sensor library @ ^1.4.2
monitor_speed = 115200

ESP32 DHT21 / AM2301A PlatformIO Example Code

Write this code in your PlatformIO project under the src/main.cpp file to use the DHT21 / AM2301A Temperature and Humidity Sensor:

#include <DHT.h>

#define DHTPIN 4
#define DHTTYPE DHT21

DHT dht(DHTPIN, DHTTYPE);

void setup() {
    Serial.begin(115200);
    Serial.println("DHT21 Sensor Example");

    dht.begin();
}

void loop() {
    // Wait a few seconds between measurements
    delay(2000);

    // Reading temperature or humidity takes about 250 milliseconds!
    float humidity = dht.readHumidity();
    // Read temperature as Celsius (the default)
    float temperature = dht.readTemperature();

    // Check if any reads failed and exit early (to try again).
    if (isnan(humidity) || isnan(temperature)) {
        Serial.println("Failed to read from DHT sensor!");
        return;
    }

    Serial.print("Humidity: ");
    Serial.print(humidity);
    Serial.print(" %	");
    Serial.print("Temperature: ");
    Serial.print(temperature);
    Serial.println(" °C");
}

This PlatformIO code demonstrates interfacing the DHT21 sensor with an ESP32 board. It initializes the sensor on GPIO pin 4, reads the temperature and humidity values every 2 seconds, and outputs the data to the Serial Monitor. The code includes checks for invalid readings and retries if necessary.

Upload the code to your ESP32 using the PlatformIO "Upload" button in your IDE or the pio run --target upload command.

ESP32 DHT21 / AM2301A MicroPython Code Example

Example in Micro Python Framework

Fill in this script in your MicroPython main.py file (main.py) to integrate the DHT21 / AM2301A Temperature and Humidity Sensor with your ESP32.

from machine import Pin
from time import sleep
import dht

# Initialize the DHT21 sensor
sensor = dht.DHT21(Pin(4))

print('DHT21 Sensor Example')

while True:
    sensor.measure()
    temperature = sensor.temperature()  # Temperature in Celsius
    humidity = sensor.humidity()  # Relative Humidity in %

    print('Temperature: {} °C'.format(temperature))
    print('Humidity: {} %'.format(humidity))

    sleep(2)

This MicroPython script uses the `dht` module to interact with the DHT21 sensor. The sensor is initialized on GPIO pin 4, and readings are taken every 2 seconds. The `sensor.measure()` method updates the data, and `sensor.temperature()` and `sensor.humidity()` retrieve the temperature and humidity values, respectively. The results are printed to the console in a user-friendly format.

Upload this code to your ESP32 using a MicroPython-compatible IDE, such as Thonny, uPyCraft, or tools like ampy.