ESP32 SHT31 / SHT31-D / GY-SHT31 / SI7021 Temperature and Humidity Sensor

Code Examples

Below you can find code examples of SHT31 / SHT31-D / GY-SHT31 / SI7021 Temperature and Humidity Sensor with ESP32 in several frameworks:

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

ESP32 SHT31 / SHT31-D / GY-SHT31 / SI7021 Arduino IDE Code Example

Example in Arduino IDE

Fill in your main Arduino IDE sketch file with the following code to use the SHT31 / SHT31-D / GY-SHT31 / SI7021 Temperature and Humidity Sensor:

#include <Wire.h>
#include "Adafruit_SHT31.h"

Adafruit_SHT31 sht31 = Adafruit_SHT31();

void setup() {
  Serial.begin(115200);
  while (!Serial) delay(10);

  if (!sht31.begin(0x44)) {   // Set to 0x45 for alternate I2C address
    Serial.println("Couldn't find SHT31");
    while (1) delay(1);
  }
}

void loop() {
  float t = sht31.readTemperature();
  float h = sht31.readHumidity();

  if (!isnan(t) && !isnan(h)) {  // Check if readings are valid
    Serial.print("Temp *C = "); Serial.print(t); Serial.print("	");
    Serial.print("Hum. % = "); Serial.println(h);
  } else {
    Serial.println("Failed to read from SHT31 sensor");
  }

  delay(1000);
}

This Arduino sketch demonstrates how to interface with the SHT31 series sensors using the Adafruit SHT31 library. It initializes the sensor and reads temperature and humidity data every second, printing the results to the Serial Monitor. If your sensor uses the alternate I2C address (0x45), adjust the initialization accordingly.

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 SHT31 / SHT31-D / GY-SHT31 / SI7021 ESP-IDF Code Example

Example in Espressif IoT Framework (ESP-IDF)

If you're using ESP-IDF to work with the SHT31 / SHT31-D / GY-SHT31 / SI7021 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/i2c.h"

#define I2C_MASTER_SCL_IO    22    /*!< GPIO number used for I2C master clock */
#define I2C_MASTER_SDA_IO    21    /*!< GPIO number used for I2C master data */
#define I2C_MASTER_NUM       I2C_NUM_0 /*!< I2C master I2C port number */
#define I2C_MASTER_FREQ_HZ   100000     /*!< I2C master clock frequency */
#define SHT31_SENSOR_ADDR    0x44       /*!< SHT31 I2C address */

static esp_err_t i2c_master_init(void) {
    i2c_config_t conf = {
        .mode = I2C_MODE_MASTER,
        .sda_io_num = I2C_MASTER_SDA_IO,
        .scl_io_num = I2C_MASTER_SCL_IO,
        .sda_pullup_en = GPIO_PULLUP_ENABLE,
        .scl_pullup_en = GPIO_PULLUP_ENABLE,
        .master.clk_speed = I2C_MASTER_FREQ_HZ,
    };
    esp_err_t err = i2c_param_config(I2C_MASTER_NUM, &conf);
    if (err != ESP_OK) {
        return err;
    }
    return i2c_driver_install(I2C_MASTER_NUM, conf.mode, 0, 0, 0);
}

void read_sht31_sensor() {
    uint8_t data[6];
    i2c_master_write_read_device(I2C_MASTER_NUM, SHT31_SENSOR_ADDR, NULL, 0, data, sizeof(data), pdMS_TO_TICKS(1000));

    uint16_t temp_raw = (data[0] << 8) | data[1];
    uint16_t hum_raw = (data[3] << 8) | data[4];

    float temperature = -45 + 175 * ((float)temp_raw / 65535.0);
    float humidity = 100 * ((float)hum_raw / 65535.0);

    printf("Temperature: %.2f °C, Humidity: %.2f %%\n", temperature, humidity);
}

void app_main() {
    ESP_ERROR_CHECK(i2c_master_init());

    while (1) {
        read_sht31_sensor();
        vTaskDelay(pdMS_TO_TICKS(2000));
    }
}

This ESP-IDF code demonstrates how to interface with SHT31-compatible sensors using the I2C protocol. It initializes I2C communication, retrieves raw temperature and humidity data, converts it to human-readable values, and prints the results 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 SHT31 / SHT31-D / GY-SHT31 / SI7021 ESPHome Code Example

Example in ESPHome (Home Assistant)

Fill in this configuration in your ESPHome YAML configuration file (example.yml) to integrate the SHT31 / SHT31-D / GY-SHT31 / SI7021 Temperature and Humidity Sensor

sensor:
  - platform: sht3x
    address: 0x44
    temperature:
      name: "Room Temperature"
    humidity:
      name: "Room Humidity"
    update_interval: 60s

This ESPHome configuration uses the `sht3x` platform to integrate SHT31 sensors. It reads and updates temperature and humidity values every 60 seconds, with descriptive names like 'Room Temperature' and 'Room Humidity.'

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

ESP32 SHT31 / SHT31-D / GY-SHT31 / SI7021 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/Adafruit SHT31 Library @ ^2.0.0
monitor_speed = 115200

ESP32 SHT31 / SHT31-D / GY-SHT31 / SI7021 PlatformIO Example Code

Write this code in your PlatformIO project under the src/main.cpp file to use the SHT31 / SHT31-D / GY-SHT31 / SI7021 Temperature and Humidity Sensor:

#include <Wire.h>
#include "Adafruit_SHT31.h"

Adafruit_SHT31 sht31 = Adafruit_SHT31();

void setup() {
    Serial.begin(115200);
    while (!Serial) delay(10);

    if (!sht31.begin(0x44)) {   // Default I2C address for SHT31
        Serial.println("Couldn't find SHT31 sensor!");
        while (1) delay(1);
    }
}

void loop() {
    float temperature = sht31.readTemperature();
    float humidity = sht31.readHumidity();

    if (!isnan(temperature) && !isnan(humidity)) {
        Serial.print("Temperature: ");
        Serial.print(temperature);
        Serial.println(" °C");

        Serial.print("Humidity: ");
        Serial.print(humidity);
        Serial.println(" %");
    } else {
        Serial.println("Failed to read from SHT31 sensor");
    }

    delay(2000);
}

This PlatformIO example initializes the SHT31 sensor using the Adafruit library, reads temperature and humidity values, and prints the results every 2 seconds. It ensures compatibility with ESP32 and Arduino-based projects.

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

ESP32 SHT31 / SHT31-D / GY-SHT31 / SI7021 MicroPython Code Example

Example in Micro Python Framework

Fill in this script in your MicroPython main.py file (main.py) to integrate the SHT31 / SHT31-D / GY-SHT31 / SI7021 Temperature and Humidity Sensor with your ESP32.

from machine import I2C, Pin
from time import sleep
import sht31

# Initialize I2C interface
i2c = I2C(0, scl=Pin(22), sda=Pin(21))

# Initialize the SHT31 sensor
sensor = sht31.SHT31(i2c, addr=0x44)

print("SHT31 Sensor Example")

while True:
    try:
        temperature, humidity = sensor.measure()
        print("Temperature: {:.2f} °C".format(temperature))
        print("Humidity: {:.2f} %".format(humidity))
    except Exception as e:
        print("Error reading from SHT31: ", e)

    sleep(2)

This MicroPython script demonstrates how to use the SHT31 sensor with an I2C interface. It reads temperature and humidity data, converts it into human-readable values, and prints the results to the console every 2 seconds.

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