Arduino library for the SHT40 digital temperature and humidity sensor.

This library provides an easy-to-use interface for the SHT40 digital temperature and humidity sensor from Sensirion. The SHT40 is a high-precision, low-power sensor that communicates via I2C.

• Simple and intuitive API
• High precision temperature and humidity readings
• I2C communication support
• CRC8 checksum verification for data integrity
• Cached readings to avoid unnecessary measurements

1. Download the library as a ZIP file
2. In the Arduino IDE, go to Sketch > Include Library > Add .ZIP Library...
3. Select the downloaded ZIP file
4. The library will be installed

Alternatively, you can clone this repository into your Arduino libraries folder:

cd <Arduino libraries folder>
git clone https://github.com/MR01Right/SHT40.git

• Arduino board (Uno, Nano, ESP32, etc.)
• SHT40 sensor module
• I2C connections (SDA, SCL)

Connect the SHT40 sensor to your Arduino:

• VCC → 3.3V or 5V (check sensor specifications)
• GND → GND
• SDA → SDA (or A4 on Arduino Uno)
• SCL → SCL (or A5 on Arduino Uno)

Note: Some boards may require pull-up resistors (typically 4.7kΩ) on SDA and SCL lines.

#include <Wire.h>
#include <SHT40.h>

SHT40 sht40;

void setup() {
  Serial.begin(9600);
  Wire.begin();  // Initialize I2C
  
  if (!sht40.begin(&Wire)) {
    Serial.println("SHT40 initialization failed!");
    while(1);
  }
  Serial.println("SHT40 initialized successfully");
}

void loop() {
  float temperature = sht40.readTemperatureC();
  float humidity = sht40.readHumidityRH();
  
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" °C");
  
  Serial.print("Humidity: ");
  Serial.print(humidity);
  Serial.println(" %RH");
  
  delay(2000);
}

#include <Wire.h>
#include <SHT40.h>

SHT40 sht40;

void setup() {
  Serial.begin(9600);
  Wire.begin();  // Initialize I2C
  
  // Initialize with custom I2C address (default is 0x44)
  sht40.begin(&Wire, 0x44);
}

void loop() {
  float temp, hum;
  
  if (sht40.measure(temp, hum)) {
    Serial.print("Temperature: ");
    Serial.print(temp);
    Serial.println(" °C");
    
    Serial.print("Humidity: ");
    Serial.print(hum);
    Serial.println(" %RH");
  } else {
    Serial.println("Measurement failed!");
  }
  
  delay(2000);
}

Constructor. Creates a new SHT40 instance.

Initializes the sensor.

• Parameters:
  • wire: Pointer to the TwoWire (I2C) object
  • address: I2C address (default: 0x44)
• Returns: true if initialization successful, false otherwise

Reads the temperature in Celsius.

• Parameters:
  • forceMeasure: If true, performs a new measurement. If false, returns the last cached value.
• Returns: Temperature in Celsius, or NAN if measurement failed

Reads the relative humidity.

• Parameters:
  • forceMeasure: If true, performs a new measurement. If false, returns the last cached value.
• Returns: Relative humidity in %RH, or NAN if measurement failed

Performs a simultaneous measurement of temperature and humidity.

• Parameters:
  • temperatureC: Reference to store the temperature value
  • humidityRH: Reference to store the humidity value
• Returns: true if measurement successful, false otherwise

• Temperature Range: -40°C to +125°C
• Temperature Accuracy: ±0.2°C (typical)
• Humidity Range: 0% to 100% RH
• Humidity Accuracy: ±1.5% RH (typical)
• I2C Address: 0x44 (default)
• Supply Voltage: 2.3V to 5.5V

This library is released under the MIT License.

MR01Right

Contributions are welcome! Please feel free to submit a Pull Request.

For issues, questions, or contributions, please visit the GitHub repository.