BH1750 Light Sensor

The BH1750 is a commonly used I2C illuminance sensor that directly outputs illuminance values, suitable for automatic lighting, agricultural supplemental lighting, shading control, and environmental logging. The current driver is a lightweight implementation that does not depend on additional third-party libraries, making it available for slim ESP32 firmware.

Wiring

BH1750	ESP32
VCC	3.3V
GND	GND
SDA	GPIO21
SCL	GPIO22

Default address is 0x23; when the ADDR pin is changed, the common address is 0x5C.

Configuration

Method 1: Web Interface Configuration (Recommended)

Before saving BH1750 configuration, verify the I2C address, sampling mode, and light range.

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 BH1750 Peripheral

1. Click the Add Peripheral button

2. Fill in the configuration:

   Field	Value	Description
   Peripheral ID	bh1750_i2c	Unique identifier
   Name	BH1750 Light	Display name
   Peripheral Type	Generic Sensor (type: 38)	I2C sensor
   SDA Pin	21	I2C data pin
   SCL Pin	22	I2C clock pin
   I2C Address	0x23	0x23 or 0x5C
   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 illuminance data (lx)

💡 Tip: BH1750 directly outputs illuminance values, no ADC conversion needed

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Method 2: JSON Configuration File Import

{
  "id": "bh1750_i2c",
  "name": "BH1750 Light",
  "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 Light Collection and Auto Light-On Rule

1. Click Peripheral Execution in the left menu
2. Click the Add Rule button
3. Configure a timer trigger:
   • Trigger Type: Timer Trigger
   • Execution Interval: 20 seconds
4. Add action:
   • Action 1: Read illuminance
     • Action Type: Sensor Read
     • Target Peripheral: bh1750_i2c
     • Data Field: illuminance
5. Enable Report Data After Execution
6. Click Save

Create Low Light Turn-On Rule

1. Create a new rule
2. Configure an event trigger:
   • Trigger Type: Event Trigger
   • Event ID: ds:bh1750_i2c_illuminance
   • Comparison: Less Than
   • Comparison Value: 80 (lx)
3. Add action:
   • Action Type: High Level
   • Target Peripheral: relay_light (lighting relay)
4. Click Save

💡 Tip: Event ID format is ds:{peripheralID}_{fieldName}

---

JSON Configuration Example

{
  "id": "exec_bh1750_read",
  "name": "BH1750 Light Collection",
  "enabled": false,
  "triggers": [
    {
      "triggerType": 1,
      "timerMode": 0,
      "intervalSec": 20
    }
  ],
  "actions": [
    {
      "targetPeriphId": "bh1750_i2c",
      "actionType": 19,
      "actionValue": "{\"periphId\":\"bh1750_i2c\",\"sensorCategory\":\"BH1750\",\"dataField\":\"illuminance\",\"sensorLabel\":\"Light\",\"unit\":\"lx\",\"decimalPlaces\":0,\"driverParams\":{\"addr\":\"0x23\",\"sda\":21,\"scl\":22}}",
      "useReceivedValue": false,
      "syncDelayMs": 0,
      "execMode": 0
    }
  ],
  "reportAfterExec": true
}

Low Light Turn-On

{
  "id": "exec_bh1750_light_on",
  "name": "Low Illuminance Light-On",
  "enabled": false,
  "triggers": [
    {
      "triggerType": 4,
      "eventId": "ds:bh1750_i2c_illuminance",
      "operatorType": 3,
      "compareValue": "80"
    }
  ],
  "actions": [
    {
      "targetPeriphId": "relay_light",
      "actionType": 0,
      "actionValue": "",
      "useReceivedValue": false,
      "syncDelayMs": 0,
      "execMode": 0
    }
  ],
  "reportAfterExec": true
}

Available Data Fields

dataField	Meaning	Unit
illuminance	Illuminance	lx