Example for dht Driver

What it Does

This example demonstrates how to configure and interact with a DHT sensor (DHT11, AM2301/DHT22, or Si7021) using the ESP-IDF framework. The DHT sensor provides temperature and humidity data, which are read and displayed every 2 seconds.

The GPIO pin and DHT sensor type can be configured via menuconfig. Additional options include enabling an internal pull-up resistor for the data line.

Configuration

To configure the example:

1. Run idf.py menuconfig.
2. Navigate to Example Configuration:
   • Select the sensor type (DHT11, AM2301/DHT22, or Si7021).
   • Set the GPIO number connected to the DHT sensor data pin.
   • Optionally, enable the internal pull-up resistor if no external pull-up is available.

Default Configuration

Setting	Description	Default
Sensor Type	Type of DHT sensor (DHT11, AM2301/DHT22, Si7021)	AM2301/DHT22
Data GPIO Number	GPIO number connected to the DHT sensor	17
Internal Pull-Up	Enable internal pull-up resistor	Disabled

Wiring

Connect the DHT sensor as follows:

DHT Sensor Pin	ESP32 Connection
VCC	3.3V
GND	Ground
Data	Configured GPIO (e.g., 17) with a pull-up resistor

Note: A pull-up resistor (typically 10kΩ) is required between the data pin and the 3.3V line. If your sensor is on a breakout board with an integrated pull-up resistor, you can enable the internal pull-up resistor via menuconfig.

Example Wiring Diagram

DHT Sensor Pin	ESP32 Pin
VCC	3.3V
GND	GND
Data	GPIO 17

Example Code

Here’s how to read data from the DHT sensor in your project:

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

static const char *TAG = "example_main";

void app_main(void)
{
    // Select sensor type and GPIO pin from menuconfig
    dht_sensor_type_t sensor_type = CONFIG_EXAMPLE_TYPE_AM2301 ? DHT_TYPE_AM2301 :
                                    CONFIG_EXAMPLE_TYPE_DHT11 ? DHT_TYPE_DHT11 : DHT_TYPE_SI7021;
    gpio_num_t gpio_num = CONFIG_ESP_TEMP_SENSOR_GPIO;

    // Enable internal pull-up resistor if specified in menuconfig
    if (CONFIG_EXAMPLE_INTERNAL_PULLUP) {
        gpio_pullup_en(gpio_num);
    } else {
        gpio_pullup_dis(gpio_num);
    }

    while (1)
    {
        float humidity = 0, temperature = 0;

        // Read data from the sensor
        esp_err_t result = dht_read_float_data(sensor_type, gpio_num, &humidity, &temperature);
        if (result == ESP_OK)
        {
            ESP_LOGI(TAG, "Humidity: %.1f%% Temperature: %.1f°C", humidity, temperature);
        }
        else
        {
            ESP_LOGE(TAG, "Failed to read sensor data: %s", esp_err_to_name(result));
        }

        vTaskDelay(pdMS_TO_TICKS(2000)); // Delay for 2 seconds
    }
}

Building and Running

Build the Project:

idf.py build

Flash the ESP32:

idf.py flash

Monitor Logs:

idf.py monitor

Example Output

I (12345) example_main: Humidity: 50.0% Temperature: 22.5°C
I (14345) example_main: Humidity: 50.1% Temperature: 22.6°C

Notes

• Ensure the DHT sensor is connected properly, and the GPIO pin matches the configuration in menuconfig.
• Use an external pull-up resistor if your breakout board does not have one.
• For stable readings, ensure the sensor is in a stable environment, free from rapid temperature or humidity changes.

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