Example 34: Flame Sensor

Experiment Overview

A flame sensor detects specific infrared wavelengths (760nm~1100nm) emitted by flames via an IR receiver tube, outputting an analog signal indicating flame intensity. Suitable for fire alarms, firefighting robots, and other safety applications.

Hardware Wiring

Board Label	GPIO Pin	Connected Device
AO	GPIO34	Flame sensor analog output
DO	GPIO4	Flame sensor digital output (optional)

When flame is detected, the analog value decreases (the larger the flame, the lower the value); digital output goes LOW.

JSON Configuration Example

{
  "peripherals": [
    {
      "id": "flame_01",
      "name": "Flame Sensor",
      "type": 15,
      "enabled": false,
      "pins": [34],
      "params": {}
    }
  ]
}

Peripheral Execution Linkage

Scenario: Fire Alarm (Polling Trigger)

Feature: Trigger buzzer and LED alarm when flame is detected (ADC < 1000)

Web UI Configuration Steps

Step 1: Ensure Alarm Peripherals are Configured

• Buzzer: buzzer_gpio (GPIO Output)
• LED: led_d1 (GPIO Output)

Step 2: Create Rule

1. Click Peripheral Execution in the left menu
2. Click New Rule button
3. Fill in basic configuration:
   • Rule Name: Fire Alarm
   • Report Data: ✅ Enabled
   • Enable: ✅ Enabled

Step 3: Configure Trigger (Polling Trigger)

1. Click Add Trigger button

2. Fill in trigger configuration:

   Field	Value	Description
   Trigger Type	Select Polling Trigger	Periodic condition check
   Target Peripheral	Select flame_01	Flame sensor
   Polling Interval	500	0.5 seconds (fast response)
   Condition Expression	value < 1000	Flame threshold

Step 4: Configure Actions (3 actions required)

Action 1: Buzzer Alarm

1. Click Add Action button
2. Fill in:
   • Action Type: Select HIGH
   • Target Peripheral: Select buzzer_gpio

Action 2: LED Alarm

1. Click Add Action button again
2. Fill in:
   • Action Type: Select LOW (common-anode LED on)
   • Target Peripheral: Select led_d1

Action 3: Send Alarm Event

1. Click Add Action button a third time

2. Fill in:

   • Action Type: Select Send Event
   • Event Type: alarm
   • Event Message: Flame detected!

3. Click Save button

Flame Sensor Value Reference

Status	ADC Value	Description
No Flame	>2000	Normal environment
Distant Flame	1000-2000	Weak flame
Close Flame	<1000	Strong flame

Notes

1. Detection Angle: Sensor detection angle is ~60°; must face the flame direction
2. Detection Range: Effective detection range is ~20-100cm (depends on flame size)
3. False Alarms: Strong sunlight or incandescent lamps may also trigger; set threshold appropriately
4. Safety Distance: Be cautious of fire safety during testing; a small lighter flame is sufficient for testing
5. Multiple Sensors: Deploy multiple sensors to cover different directions