SHT31 / SHT3x with ESP32

Specifications

Power and logic levels

3.3 V: safe to connect directly

ESP32 pins, including those on a display board's connectors, work at 3.3 V and are not 5 V tolerant. Modules differ, so if in doubt, measure the signal before you connect it.

Wiring

Arduino code

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

const int SDA_PIN = 8, SCL_PIN = 9;   // use your board's I2C pins
Adafruit_SHT31 sht;

void setup() {
  Serial.begin(115200);
  Wire.begin(SDA_PIN, SCL_PIN);
  if (!sht.begin(0x44)) {
    Serial.println("SHT31 not found: check wiring or try 0x45");
    while (true) delay(1000);
  }
}

void loop() {
  Serial.printf("%.2f C  %.1f %%\n", sht.readTemperature(), sht.readHumidity());
  delay(2000);
}

Needs the Adafruit SHT31 library. Compiled for ESP32-S3 with arduino-esp32 3.x. Not yet tested by us on a physical sensor. Change the pins to match your board.

On a display

LCD Ultra Pro has this sensor as a built-in value source. Choose it in a rule, and a label or gauge shows the reading without writing code.

Boards with a ready connector

Only boards whose connectors we have surveyed. Others may still work on free GPIOs.

Good to know

• Leave the heater off for normal readings.
• Modules usually use 0x44. The ADDR pin selects 0x45.
• Keep it out of the warm air around the display board.

What it is good for

• Greenhouse and humidor monitors
• Thermostats
• Bathroom and cellar humidity control

FAQ

Sources

• https://sensirion.com/products/catalog/SHT31-DIS-B

Related parts

• BME280
• SCD40
• DS18B20