Example 32: Sound Sensor

Experiment Overview

A sound sensor detects ambient sound intensity via an electret microphone, outputting an analog signal (sound level) and a digital signal (whether a threshold is exceeded). Suitable for voice-activated switches, noise monitoring, and similar applications.

Hardware Wiring

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

JSON Configuration Example

{
  "peripherals": [
    {
      "id": "sound_01",
      "name": "Sound Sensor",
      "type": 15,
      "enabled": false,
      "pins": [34],
      "params": {}
    }
  ]
}

Peripheral Execution Linkage

Scenario: Voice-Controlled Light (Polling Trigger)

Feature: Toggle LED when sound is detected (ADC > 2500)

Web UI Configuration Steps

Step 1: Ensure LED Peripheral is Configured

• Peripheral ID: led_d1
• Type: GPIO Output

Step 2: Create Rule

1. Click Peripheral Config in the left menu → Switch to Peripheral Execution tab
2. Click New Rule button
3. Fill in basic configuration:
   • Rule Name: Voice-Controlled Light
   • 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 sound_01	Sound sensor
   Polling Interval	100	100ms (fast detection)
   Condition Expression	value > 2500	Sound intensity threshold

Step 4: Configure Action

1. Click Add Action button

2. Fill in:

   • Action Type: Select Toggle Level
   • Target Peripheral: Select led_d1

3. Click Save button

Sound Sensor Value Reference

Status	ADC Value	Description
Silence	~2048	Baseline value (midpoint)
Soft Sound	2000-2500	Slight sound
Normal Speech	2500-3500	Conversation volume
Loud Sound	>3500	Clapping, shouting

Notes

1. Sensitivity: Module potentiometer adjusts sensitivity / digital output threshold
2. Sampling Rate: Sound changes rapidly; 50-100ms sampling recommended
3. Baseline Drift: Baseline values differ across environments with different ambient noise; calibration required
4. Signal Amplitude: ADC reads ~2048 (midpoint) at silence; fluctuation range depends on volume