Example 1: Light First LED

Experiment Overview

Control the on/off state of an LED via GPIO digital output, the introductory experiment for embedded development. The Puzhong development board has 4 LEDs (D1-D4), connected to GPIO15, GPIO2, GPIO0, GPIO4 respectively.

Hardware Wiring

Board Label	GPIO Pin	Connected Device
D1	GPIO15	LED (active low)
D2	GPIO2	LED (active low)
D3	GPIO0	LED (active low)
D4	GPIO4	LED (active low)

The Puzhong board LEDs use common-anode wiring, GPIO outputs LOW to light the LED.

JSON Configuration Example

{
  "peripherals": [
    {
      "id": "led_d1",
      "name": "LED-D1",
      "type": 12,
      "enabled": false,
      "pins": [15],
      "params": {
        "initialState": 0
      }
    },
    {
      "id": "led_d2",
      "name": "LED-D2",
      "type": 12,
      "enabled": false,
      "pins": [2],
      "params": {
        "initialState": 0
      }
    },
    {
      "id": "led_d3",
      "name": "LED-D3",
      "type": 12,
      "enabled": false,
      "pins": [0],
      "params": {
        "initialState": 0
      }
    },
    {
      "id": "led_d4",
      "name": "LED-D4",
      "type": 12,
      "enabled": false,
      "pins": [4],
      "params": {
        "initialState": 0
      }
    }
  ]
}

Peripheral Execution Linkage

Scenario 1: Remote Control LED (Platform Trigger)

Function: Control LED via MQTT/HTTP commands from the cloud platform

Web Interface Configuration Steps

Step 1: Create Rule

1. Click left menu Peripheral Configuration → Switch to Peripheral Execution Management tab
2. Click New Rule button
3. Fill in basic configuration:
   • Rule Name: Remote Control LED-D1
   • Report Data: ✅ Enable (report execution status to cloud platform)
   • Enabled: ✅ Enable

Step 2: Configure Trigger

1. Click Add Trigger button

2. Fill in trigger configuration:

   Field	Value	Description
   Trigger Type	Select Platform Trigger	Receive cloud platform commands
   Target Peripheral	Leave empty or select led_d1	Peripheral receiving the command
   Operator	Select Match Pattern	Trigger when received data equals comparison value
   Comparison Value	{"cmd":"on"}	Command content to match

Step 3: Configure Action

1. Click Add Action button

2. Fill in action configuration:

   Field	Value	Description
   Action Type	Select LOW Level	GPIO output LOW, lights up LED
   Target Peripheral	Select led_d1	Peripheral ID to control
   Execution Mode	Select Synchronous	Wait for action to complete

3. Click Save button

Test Method:

Send MQTT message via cloud platform:

{"cmd":"on"}

---

Scenario 2: Timed LED Blink (Timer Trigger)

Function: Make LED blink once per second

Web Interface Configuration Steps

Step 1: Create Rule

1. Click New Rule
2. Fill in basic configuration:
   • Rule Name: LED-D1 Blink
   • Report Data: ❌ Disable (no need to report)
   • Enabled: ✅ Enable

Step 2: Configure Trigger

1. Click Add Trigger button

2. Fill in trigger configuration:

   Field	Value	Description
   Trigger Type	Select Timer Trigger	Execute at time intervals
   Timer Mode	Select Interval Timer	Execute every X seconds
   Interval Seconds	1	Execute every 1 second

Step 3: Configure Actions (2 actions needed for blinking)

Action 1: Turn on LED

1. Click Add Action button
2. Fill in:
   • Action Type: Select LOW Level
   • Target Peripheral: Select led_d1

Action 2: Delay then turn off LED

1. Click Add Action button again

2. Fill in:

   • Action Type: Select Command Script
   • Script Content:

     DELAY 500
     PERIPH led_d1 HIGH

   • Execution Mode: Select Asynchronous

3. Click Save button

Execution Flow:

Every 1 second
  ↓
Turn on LED (LOW level)
  ↓
Delay 500ms
  ↓
Turn off LED (HIGH level)
  ↓
Wait for next 1-second cycle

{
  "name": "Remote Control LED-D1",
  "enabled": true,
  "triggers": [
    { "type": "platform", "params": { "topic": "led/d1" } }
  ],
  "actions": [
    { "type": "gpio_write", "params": { "peripheralId": "led_d1", "value": 0 } }
  ]
}

Notes

1. GPIO0: Must be pulled LOW during flashing, can be used as LED output during normal operation, but be careful during debugging
2. GPIO2: Some ESP32 modules have a built-in LED also connected to this pin
3. Level Logic: Puzhong board LEDs are active-low, opposite to the common active-high convention
4. Current Limiting: ESP32 GPIO outputs max 12mA, onboard LEDs already have current-limiting resistors