SHT30 Arduino: Wiring, 0x44/0x45, Code & Fixes

1. How do you wire an SHT30 to Arduino?

A digital SHT30 module needs four connections: supply, ground, SDA and SCL. Confirm that the board is an I2C version before using this guide; analog modules with separate temperature and humidity voltage outputs require different code.

ESP32 and ESP8266 boards can route I2C to other suitable GPIO pins. Use the pin assignment in your board definition when it differs from the common mapping above.

2. How do you find the SHT30 I2C address?

The SHT30-DIS uses the 7-bit I2C address 0x44 when ADDR is low and 0x45 when ADDR is high, according to the Sensirion SHT3x-DIS datasheet. Most breakout boards are fixed at 0x44.

Run a scanner before changing libraries. An address acknowledgement proves that a device answered, but it does not prove that measurements or cyclic redundancy check (CRC) data are valid.

#include <Wire.h>

void setup() {
  Serial.begin(115200);
  Wire.begin();
}

void loop() {
  byte count = 0;
  for (byte address = 1; address < 127; address++) {
    Wire.beginTransmission(address);
    if (Wire.endTransmission() == 0) {
      Serial.print("I2C device: 0x");
      if (address < 16) Serial.print('0');
      Serial.println(address, HEX);
      count++;
    }
  }
  if (count == 0) Serial.println("No I2C devices found");
  delay(3000);
}

3. How do you read an SHT30 with Arduino?

The Adafruit SHT31 library is a common Arduino option for compatible SHT30 devices because the parts share the SHT3x command family. Install the library and its required dependencies through Arduino Library Manager.

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

Adafruit_SHT31 sht30 = Adafruit_SHT31();

void setup() {
  Serial.begin(115200);
  Wire.begin();

  if (!sht30.begin(0x44)) {
    Serial.println("SHT30 not found");
    while (1) delay(10);
  }
}

void loop() {
  float temperature = sht30.readTemperature();
  float humidity = sht30.readHumidity();

  if (isnan(temperature) || isnan(humidity)) {
    Serial.println("Measurement failed");
  } else {
    Serial.print("Temperature: ");
    Serial.print(temperature, 1);
    Serial.print(" °C  Humidity: ");
    Serial.print(humidity, 1);
    Serial.println(" %RH");
  }
  delay(2000);
}

If the scanner reports 0x45, change only the initialization address to sht30.begin(0x45).

4. Why is the SHT30 not detected or returning NaN?

Use the scan result to split the fault. No address points to power, wiring or pull-ups. An address with failed measurements points to device identity, command handling, supply noise or signal integrity.

Do not treat every NaN as a library problem. A marginal I2C bus can acknowledge an address but still corrupt the measurement transaction.

5. What electrical checks matter most?

Check the pull-up network

I2C requires pull-ups on SDA and SCL. A common starting value is 4.7 kΩ, but multiple breakout boards place resistors in parallel. Two 4.7 kΩ pull-ups in parallel produce about 2.35 kΩ.

Place 100 nF near the sensor

The Sensirion SHT3x-DIS datasheet specifies a 100 nF ceramic capacitor between VDD and GND, placed as close to the sensor as possible. Keep the VDD-capacitor-GND loop short.

Check the module before using 5 V

The SHT30-DIS sensor supports a 2.15–5.5 V supply range, but the breakout board controls the interface conditions. Check its regulator, level shifting and SDA/SCL pull-up voltage before connecting it to a 5 V controller.

6. Why can SHT30 temperature read too high?

The SHT30 measures the temperature at its physical location. Heat from an MCU, Wi-Fi system-on-chip, regulator, DC/DC converter, MOSFET, LED or high-current trace can raise the reading even when communication is correct.

Place the sensor near a ventilated board edge and away from large copper areas connected to hot components. If readings stay high, compare normal operation, reduced-power operation and a temporarily isolated sensor position.

For production-focused design considerations, SHT30 low-humidity and reflow engineering guide.

The shortest reliable setup path

1. Confirm that the module is a digital I2C SHT30.
2. Connect power, ground, SDA and SCL.
3. Scan for 0x44 or 0x45.
4. Run the short library example.
5. If measurement fails after detection, check supply noise, pull-ups and bus timing.

SHT30, SHT31 and SHT3x product names are identifiers or trademarks of their respective owners. NYFEA and FHT30 are independent and are not affiliated with, endorsed by, or sponsored by those owners. References are provided for engineering identification and comparison.