Light-Sensitive Auto Light Control Scenario

Scenario Description

Use a photosensitive sensor (ADC) to detect ambient light intensity. When light falls below a threshold, automatically turn on the light (relay); when light recovers, automatically turn off the light.

Required Peripherals

Peripheral	Type	Description
light_sensor	GPIO_ANALOG_INPUT(15)	Photosensitive resistor ADC
relay_light	GPIO_DIGITAL_OUTPUT(12)	Light relay

Complete Configuration Process

Method 1: Web Interface Configuration (Recommended)

This scenario requires first adding the photosensitive ADC and lighting relay, then using peripheral execution rules for threshold evaluation and on/off control.

Step 1: Configure Peripherals

Step 1: Open 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 Photosensitive Sensor

1. Click the Add Peripheral button

2. Fill in the configuration:

   Field	Value	Description
   Peripheral ID	light_sensor	Light sensor
   Name	Light Sensor	Display name
   Peripheral Type	GPIO Analog Input (type: 15)	ADC collection
   Pin Configuration	36	AO connected to GPIO36 (ADC1)
   Initial State	0	Default

3. Click Save

Step 3: Add Lighting Relay

1. Click the Add Peripheral button again

2. Fill in the configuration:

   Field	Value	Description
   Peripheral ID	relay_light	Lighting relay
   Name	Lighting Relay	Display name
   Peripheral Type	GPIO Digital Output (type: 12)	Relay control
   Pin Configuration	15	IN connected to GPIO15
   Initial State	0	Default off

3. Click Save

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Step 2: Configure Peripheral Execution Rules

Rule 1: Turn On Light When Dark

1. Switch to Peripheral Execution Management tab

2. Click the Add Rule button

3. Fill in basic configuration:

   • Rule Name: Turn On Light When Dark
   • Report Data: ✅ Enabled
   • Enable: ✅ Enabled

4. Configure trigger:

   • Trigger Type: Select Platform Trigger
   • Target Peripheral ID: Enter light_sensor
   • Operator: Select Less Than (<)
   • Threshold: 500 (low voltage when dark)

5. Configure action:

   • Action Type: Select High Level
   • Target Peripheral: Select relay_light

6. Click Save

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Rule 2: Turn Off Light When Bright

1. Create rule, name: Turn Off Light When Bright

2. Trigger configuration:

   • Trigger Type: Select Platform Trigger
   • Target Peripheral ID: Enter light_sensor
   • Operator: Select Greater Than (>)
   • Threshold: 2000 (high voltage when bright)

3. Action configuration:

   • Action Type: Select Low Level
   • Target Peripheral: Select relay_light

4. Click Save

💡 Tip: Light-on threshold 500, light-off threshold 2000, forming a 1500 hysteresis band to prevent frequent switching

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Method 2: JSON Configuration File Import

Working Principle

1. Photosensitive resistor and fixed resistor form a voltage divider; ADC reads the voltage at the divider point
2. Stronger light → lower photosensitive resistance → higher ADC value
3. Dimmer light → higher photosensitive resistance → lower ADC value
4. Set dark threshold (500) and bright threshold (2000) to form a hysteresis band, avoiding frequent switching

Precautions

1. Hysteresis Design: Gap between light-on threshold (500) and light-off threshold (2000) prevents jitter
2. Sensor Direction: Some photosensitive modules have inverted logic (higher value when darker); comparison direction needs to be swapped
3. ADC Pins: Use ADC1 channels (GPIO32-39) to avoid WiFi conflicts