SHT31 Temperature and Humidity Sensor

The SHT31 is a commonly used I2C temperature and humidity sensor with better accuracy and stability than the DHT11, suitable for environmental monitoring, temperature control, and constant humidity scenarios. The current driver is a lightweight implementation that does not depend on additional third-party libraries, and is available for esp32, esp32c3, esp32s3, and esp32s3-F16R8.

Wiring

SHT31	ESP32
VCC	3.3V
GND	GND
SDA	GPIO21
SCL	GPIO22

Default address is 0x44; some modules can be switched to 0x45.

Configuration

Method 1: Web Interface Configuration (Recommended)

Before saving SHT31 configuration, verify the I2C address, sampling interval, and temperature/humidity fields.

Step 1: Navigate to Peripheral Management Page

1. Open a browser and navigate to the ESP32 IP address
2. After logging in, click Peripheral Configuration in the left menu

Step 2: Add SHT31 Peripheral

1. Click the Add Peripheral button

2. Fill in the configuration:

   Field	Value	Description
   Peripheral ID	sht31_i2c	Unique identifier
   Name	SHT31 Temp & Humidity	Display name
   Peripheral Type	Generic Sensor (type: 38)	I2C sensor
   SDA Pin	21	I2C data pin
   SCL Pin	22	I2C clock pin
   I2C Address	0x44	0x44 or 0x45
   Sampling Interval	5000	5 seconds

3. Click Save

Step 3: Verify Configuration

1. Find the newly added peripheral in the peripheral list
2. Click the Enable toggle
3. Wait 5 seconds and check temperature and humidity data

💡 Tip: SHT31 has better accuracy and stability than DHT11, supported by all ESP32 variants

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Method 2: JSON Configuration File Import

{
  "id": "sht31_i2c",
  "name": "SHT31 Temp & Humidity",
  "type": 2,
  "enabled": false,
  "pinCount": 2,
  "pins": [21, 22, 255, 255, 255, 255, 255, 255],
  "params": {
    "frequency": 100000,
    "address": 0,
    "isMaster": true
  }
}

Peripheral Execution Integration

Web Interface Configuration Steps

Create Temperature Collection and Control Rule

1. Switch to the Peripheral Execution Management tab
2. Click the Add Rule button
3. Configure a timer trigger:
   • Trigger Type: Timer Trigger
   • Execution Interval: 30 seconds
4. Add action:
   • Action 1: Read temperature
     • Action Type: Sensor Read
     • Target Peripheral: sht31_i2c
     • Data Field: temperature
5. Enable Report Data After Execution
6. Click Save

Create High Temperature Relay Rule

1. Create a new rule
2. Configure an event trigger:
   • Trigger Type: Event Trigger
   • Event ID: ds:sht31_i2c_temperature
   • Comparison: Greater Than
   • Comparison Value: 35 (℃)
3. Add action:
   • Action Type: High Level
   • Target Peripheral: relay_01 (fan relay)
4. Click Save

💡 Tip: SHT31 is suitable for precision temperature control and constant humidity scenarios

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JSON Configuration Example

{
  "id": "exec_sht31_temperature_read",
  "name": "SHT31 Temperature Collection",
  "enabled": false,
  "triggers": [
    {
      "triggerType": 1,
      "timerMode": 0,
      "intervalSec": 30
    }
  ],
  "actions": [
    {
      "targetPeriphId": "sht31_i2c",
      "actionType": 19,
      "actionValue": "{\"periphId\":\"sht31_i2c\",\"sensorCategory\":\"SHT31\",\"dataField\":\"temperature\",\"sensorLabel\":\"Temperature\",\"unit\":\"℃\",\"decimalPlaces\":1,\"driverParams\":{\"addr\":\"0x44\",\"sda\":21,\"scl\":22}}",
      "useReceivedValue": false,
      "syncDelayMs": 0,
      "execMode": 0
    }
  ],
  "reportAfterExec": true
}

High Temperature Relay

{
  "id": "exec_sht31_hot_relay",
  "name": "SHT31 High Temperature Relay",
  "enabled": false,
  "triggers": [
    {
      "triggerType": 4,
      "eventId": "ds:sht31_i2c_temperature",
      "operatorType": 2,
      "compareValue": "35"
    }
  ],
  "actions": [
    {
      "targetPeriphId": "relay_01",
      "actionType": 0,
      "actionValue": "",
      "useReceivedValue": false,
      "syncDelayMs": 0,
      "execMode": 0
    }
  ],
  "reportAfterExec": true
}

Available Data Fields

dataField	Meaning	Unit
temperature	Temperature	℃
humidity	Relative Humidity	%