How to Use StrawberryLinux SHT25 Sensor module: Examples, Pinouts, and Specs

The StrawberryLinux SHT25 Sensor Module is a high-precision digital temperature and humidity sensor designed for environmental monitoring applications. It features a compact design and communicates via the I2C protocol, making it easy to integrate into a wide range of projects. The module is based on the SHT25 sensor, which offers excellent accuracy and reliability for temperature and humidity measurements.

• Weather stations
• HVAC (Heating, Ventilation, and Air Conditioning) systems
• IoT (Internet of Things) devices for environmental monitoring
• Industrial and agricultural monitoring systems
• Data logging and scientific research

The following table outlines the key technical specifications of the StrawberryLinux SHT25 Sensor Module:

The module has a 4-pin interface for easy connection. The pinout is as follows:

1. Power the Module: Connect the VCC pin to a 3.3V or 5V power source and the GND pin to ground.
2. Connect I2C Lines: Connect the SDA and SCL pins to the corresponding I2C pins on your microcontroller (e.g., Arduino UNO: A4 for SDA and A5 for SCL).
3. Pull-Up Resistors: Ensure that the I2C lines have pull-up resistors (typically 4.7kΩ). Some microcontrollers have built-in pull-ups, but external resistors may be required for reliable communication.
4. Write Code: Use an appropriate library or write custom code to communicate with the sensor via I2C.

• Power Supply: Ensure the power supply voltage is within the specified range (3.0V to 5.5V).
• I2C Address: The default I2C address of the SHT25 sensor is 0x40. Ensure no other devices on the I2C bus conflict with this address.
• Measurement Timing: Allow sufficient time between measurements to avoid overloading the sensor. A typical interval is 1 second.
• Environmental Protection: If used in harsh environments, consider adding a protective enclosure to shield the sensor from dust and moisture.

Below is an example Arduino sketch to read temperature and humidity data from the SHT25 sensor:

#include <Wire.h>

// SHT25 I2C address
#define SHT25_ADDRESS 0x40

// Command codes for temperature and humidity measurements
#define CMD_MEASURE_TEMP 0xE3
#define CMD_MEASURE_HUM  0xE5

void setup() {
  Wire.begin(); // Initialize I2C communication
  Serial.begin(9600); // Initialize serial communication for debugging
  Serial.println("SHT25 Sensor Module Test");
}

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

  // Print the results to the Serial Monitor
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" °C");

  Serial.print("Humidity: ");
  Serial.print(humidity);
  Serial.println(" %RH");

  delay(1000); // Wait 1 second before the next measurement
}

float readTemperature() {
  Wire.beginTransmission(SHT25_ADDRESS);
  Wire.write(CMD_MEASURE_TEMP); // Send temperature measurement command
  Wire.endTransmission();
  delay(85); // Wait for the measurement to complete

  Wire.requestFrom(SHT25_ADDRESS, 2);
  if (Wire.available() == 2) {
    uint16_t rawData = (Wire.read() << 8) | Wire.read();
    return -46.85 + 175.72 * (rawData / 65536.0); // Convert to Celsius
  }
  return NAN; // Return NaN if data is unavailable
}

float readHumidity() {
  Wire.beginTransmission(SHT25_ADDRESS);
  Wire.write(CMD_MEASURE_HUM); // Send humidity measurement command
  Wire.endTransmission();
  delay(29); // Wait for the measurement to complete

  Wire.requestFrom(SHT25_ADDRESS, 2);
  if (Wire.available() == 2) {
    uint16_t rawData = (Wire.read() << 8) | Wire.read();
    return -6.0 + 125.0 * (rawData / 65536.0); // Convert to %RH
  }
  return NAN; // Return NaN if data is unavailable
}

1. No Data from the Sensor

   • Cause: Incorrect wiring or loose connections.
   • Solution: Double-check the wiring and ensure all connections are secure.

2. I2C Communication Failure

   • Cause: Conflicting I2C addresses or missing pull-up resistors.
   • Solution: Verify the I2C address (0x40) and ensure pull-up resistors are present on the SDA and SCL lines.

3. Inaccurate Readings

   • Cause: Environmental factors such as condensation or dust on the sensor.
   • Solution: Clean the sensor gently with a dry, soft cloth and consider using a protective enclosure.

4. Arduino Code Not Working

   • Cause: Missing or outdated libraries.
   • Solution: Ensure the Arduino IDE is up to date and that the Wire library is included in your sketch.

Q: Can the SHT25 Sensor Module operate at 5V?
A: Yes, the module supports a supply voltage range of 3.0V to 5.5V.

Q: What is the typical response time for measurements?
A: The typical response time is 8 seconds for humidity and less than 1 second for temperature.

Q: Can I use this module with a Raspberry Pi?
A: Yes, the module can be used with any microcontroller or SBC (Single Board Computer) that supports I2C communication.

Q: Is the sensor factory-calibrated?
A: Yes, the SHT25 sensor is factory-calibrated for temperature and humidity measurements.