Example 9: External Interrupt

Experiment Overview

Detect external signal changes (button press, sensor trigger, etc.) via GPIO interrupts, immediately triggering events when rising edge, falling edge or level change is detected. Compared to polling, interrupts respond faster and do not consume CPU resources.

Hardware Wiring

Board Label	GPIO Pin	Connected Device
KEY1	GPIO14	Button/Sensor (falling edge trigger)

Any interrupt-capable GPIO pin can be used, almost all ESP32 GPIOs support interrupts.

JSON Configuration Example

{
  "peripherals": [
    {
      "id": "int_falling",
      "name": "Falling Edge Interrupt",
      "type": 19,
      "enabled": false,
      "pins": [14],
      "params": {}
    },
    {
      "id": "int_rising",
      "name": "Rising Edge Interrupt",
      "type": 18,
      "enabled": false,
      "pins": [27],
      "params": {}
    },
    {
      "id": "int_change",
      "name": "Level Change Interrupt",
      "type": 20,
      "enabled": false,
      "pins": [26],
      "params": {}
    }
  ]
}

Peripheral Execution Linkage

Scenario: Interrupt Triggered Alarm (Event Trigger)

Function: When falling edge interrupt is detected (button press), buzzer sounds for 0.5 seconds

Web Interface Configuration Steps

Step 1: Ensure buzzer peripheral is configured

• Peripheral ID: buzzer_gpio
• Type: 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: Interrupt Alarm
   • Report Data: ✅ Enable
   • Enabled: ✅ Enable

Step 3: Configure Trigger (Event Trigger)

1. Click Add Trigger button

2. Fill in trigger configuration:

   Field	Value	Description
   Trigger Type	Select Event Trigger	Respond to system events
   Event Type	100	GPIO interrupt event
   Event Source	int_falling	Falling edge interrupt peripheral ID

Step 4: Configure Actions (3 actions needed)

Action 1: Buzzer ON

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

Action 2: Delay 500ms

1. Click Add Action button again
2. Fill in:
   • Action Type: Select Delay
   • Action Params: 500 (milliseconds)

Action 3: Buzzer OFF

1. Click Add Action button a third time

2. Fill in:

   • Action Type: Select LOW Level
   • Target Peripheral: Select buzzer_gpio

3. Click Save button

Execution Flow:

Button pressed (falling edge)
  ↓
Trigger interrupt event
  ↓
Buzzer ON (HIGH)
  ↓
Delay 500ms
  ↓
Buzzer OFF (LOW)

Interrupt Type Reference

Interrupt Type	Trigger Condition	Use Case	Type Value
Rising Edge	LOW→HIGH change	Button release, sensor trigger	18
Falling Edge	HIGH→LOW change	Button press, sensor trigger	19
Level Change	Any level change	Monitor signal changes	20

Notes

1. Debouncing: Mechanical buttons produce bounce, FastBee has built-in 50ms debounce protection
2. Interrupt Safety: Time-consuming operations cannot be executed in interrupt callbacks, FastBee uses event queue for async processing
3. Pin Restrictions: GPIO6-11 (SPI Flash) cannot be used for interrupts
4. Level Requirement: ESP32 GPIO is 3.3V level, 5V signals need voltage division
5. Wake-up Feature: Some pins (RTC GPIO) support deep sleep interrupt wake-up