IoT Smart Light Control

Overview

Control lights, relays, or any GPIO-connected devices on a Raspberry Pi through natural language conversation. Turn devices on/off, check status, and automate with scheduled jobs. What it does:

Toggle relay or LED on/off via chat
Control GPIO pins remotely
Schedule automated on/off times
Safe, authenticated edge API

Hardware: Raspberry Pi 4/5, relay module (optocoupled recommended), jumper wires APIs used: Custom Edge API on Raspberry Pi

Architecture

User Chat → Lua Agent → SetRelayTool → Edge API (Flask) → GPIO → Relay → Physical Device

Complete Implementation

Edge API on Raspberry Pi

Setup (one-time)

# Install OS packages
sudo apt update
sudo apt install -y python3-pip python3-venv python3-libgpiod

# Add user to gpio group (required for GPIO access without sudo)
sudo adduser $USER gpio
# Log out and back in (or reboot) for this to take effect

# Create project folder
mkdir -p ~/iot-edge && cd ~/iot-edge
python3 -m venv .venv
source .venv/bin/activate

# Install dependencies
pip install flask gpiozero

Important: After adding your user to the gpio group, you must log out and back in (or reboot) for permissions to take effect.

Edge API Code

Create edge_api.py:

from flask import Flask, request, jsonify
from functools import wraps
from gpiozero import OutputDevice
import os, time

app = Flask(__name__)
API_KEY = os.environ.get("EDGE_API_KEY", "changeme")

def require_key(fn):
    @wraps(fn)
    def wrapper(*args, **kwargs):
        if request.headers.get("X-API-Key") != API_KEY:
            return jsonify({"error": "unauthorized"}), 401
        return fn(*args, **kwargs)
    return wrapper

@app.get("/health")
def health():
    return {"ok": True, "ts": int(time.time())}

@app.post("/gpio/relay")
@require_key
def gpio_relay():
    data = request.get_json(force=True)
    pin = int(data.get("pin", 17))               # BCM pin number
    state = str(data.get("state", "off")).lower()
    active_low = bool(data.get("active_low", True))  # many relay boards are active-low

    dev = OutputDevice(pin, active_high=not active_low, initial_value=False)
    if state == "on":
        dev.on()
    else:
        dev.off()
    
    return {"pin": pin, "state": state, "active_low": active_low}

if __name__ == "__main__":
    app.run(host="0.0.0.0", port=5001)

Run the Edge API

export EDGE_API_KEY="supersecret"
python edge_api.py

Test Edge API

# Health check
curl http://raspberrypi.local:5001/health

# Turn relay on
curl -X POST http://raspberrypi.local:5001/gpio/relay \
  -H "X-API-Key: supersecret" \
  -H "Content-Type: application/json" \
  -d '{"pin":17,"state":"on","active_low":true}'

Lua Agent Implementation

src/tools/SetRelayTool.ts

import { LuaTool, env } from 'lua-cli';
import { z } from 'zod';

export default class SetRelayTool implements LuaTool {
  name = "set_relay";
  description = "Turn a GPIO relay or LED on/off on the Raspberry Pi";
  
  inputSchema = z.object({
    pin: z.number().int().default(17).describe("BCM GPIO pin number"),
    state: z.enum(["on","off"]).describe("Turn device on or off"),
    active_low: z.boolean().default(true).describe("Many relay boards are active-low")
  });

  async execute(input: z.infer<typeof this.inputSchema>) {
    const base = env('PI_BASE_URL');
    const key = env('PI_API_KEY');
    
    if (!base || !key) {
      throw new Error('PI_BASE_URL or PI_API_KEY not configured');
    }

    const res = await fetch(`${base}/gpio/relay`, {
      method: 'POST',
      headers: { 
        'Content-Type': 'application/json', 
        'X-API-Key': key 
      },
      body: JSON.stringify(input)
    });
    
    if (!res.ok) {
      throw new Error(`Edge API error: ${res.status} ${await res.text()}`);
    }
    
    const result = await res.json();
    
    return {
      success: true,
      pin: result.pin,
      state: result.state,
      message: `GPIO pin ${result.pin} turned ${result.state}`
    };
  }
}

src/index.ts

import { LuaAgent, LuaSkill, LuaJob } from 'lua-cli';
import SetRelayTool from './tools/SetRelayTool';

// IoT control skill
const iotSkill = new LuaSkill({
  name: "raspberry-pi-gpio",
  description: "Control GPIO devices on Raspberry Pi",
  context: `
    This skill controls physical devices on a Raspberry Pi.
    
    - set_relay: Turn GPIO relay or LED on/off
      Use when user asks to control lights, fans, or any GPIO device
      
    Safety:
    - Always confirm which device a pin controls before toggling
    - Never rapidly toggle relays without user intent
    - Mention current state after changing
  `,
  tools: [new SetRelayTool()]
});

// Scheduled job: Turn off grow light at night
const nighttimeOffJob = new LuaJob({
  name: 'nighttime-off',
  description: 'Turn off grow light at 10 PM',
  schedule: {
    type: 'cron',
    pattern: '0 22 * * *'  // 10 PM daily
  },
  execute: async (job) => {
    const tool = new SetRelayTool();
    await tool.execute({ pin: 17, state: 'off', active_low: true });
    
    const user = await job.user();
    await user.send([{
      type: 'text',
      text: '🌙 Grow light turned off for the night.'
    }]);
  }
});

// Configure agent
export const agent = new LuaAgent({
  name: "smart-home-agent",
  
  persona: `You are a smart home automation assistant controlling Raspberry Pi devices.
  
Your role:
- Control lights, fans, and GPIO devices
- Confirm actions before making physical changes
- Report current device states
- Provide clear feedback on actions

Communication style:
- Clear and confirmatory
- Safety-conscious
- Brief and actionable

Safety practices:
- Always confirm which device you're controlling
- Mention current state after changes
- Don't rapidly toggle devices
- Warn if unsure about pin assignments

Device knowledge:
- Pin 17: Grow light (active-low relay)
- Pin 18: Ventilation fan
- Pin 27: LED indicator`,

  
  skills: [iotSkill],
  jobs: [nighttimeOffJob]
});

Uses LuaAgent with scheduled jobs for automated device control (e.g., turn off lights at night).

Environment Setup

# .env
PI_BASE_URL=http://raspberrypi.local:5001
PI_API_KEY=supersecret

Or set via CLI:

lua env sandbox
# Add: PI_BASE_URL and PI_API_KEY

Testing

Test Edge API Directly

# Turn relay on
curl -X POST http://raspberrypi.local:5001/gpio/relay \
  -H "X-API-Key: supersecret" \
  -H "Content-Type: application/json" \
  -d '{"pin":17,"state":"on","active_low":true}'

Test with Lua

# Test tool directly
lua test
# Select: set_relay
# Input: pin=17, state=on

# Test conversationally
lua chat
# You: "Turn on the grow light"
# You: "Turn off pin 17"

Wiring

Relay Module (Active-Low):

Raspberry Pi          Relay Module
-----------          -------------
3.3V        ────────> VCC
GND         ────────> GND
GPIO 17     ────────> IN (Signal)
                       
Relay Output ─────> Your Device (Light/Fan)

Safety: Use optocoupled relay modules for AC loads. Never exceed the relay’s rated voltage/current. Always verify correct wiring before powering on.

Production Deployment

Run Edge API on Boot

Create systemd service /etc/systemd/system/iot-edge.service:

[Unit]
Description=IoT Edge API
After=network-online.target

[Service]
User=pi
WorkingDirectory=/home/pi/iot-edge
Environment=EDGE_API_KEY=supersecret
ExecStart=/home/pi/iot-edge/.venv/bin/flask --app edge_api run --host=0.0.0.0 --port=5001
Restart=always

[Install]
WantedBy=multi-user.target

Enable and start:

sudo systemctl daemon-reload
sudo systemctl enable --now iot-edge

Key Features

Remote Control

Control GPIO devices from anywhere via chat

Secure API

API key authentication protects your edge API

Scheduled Automation

Jobs for automated on/off schedules

Safety First

Confirmation before physical state changes

Next IoT Demo

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Read temperature, humidity, and pressure from BME280 sensor

Welcome

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Key Concepts

Featured Demos

IoT Smart Light Control

Overview

Architecture

Complete Implementation

Edge API on Raspberry Pi

Setup (one-time)

Edge API Code

Run the Edge API

Test Edge API

Lua Agent Implementation

src/tools/SetRelayTool.ts

src/index.ts

Environment Setup

Testing

Test Edge API Directly

Test with Lua

Wiring

Production Deployment

Run Edge API on Boot

Key Features

Remote Control

Secure API

Scheduled Automation

Safety First

Next IoT Demo

Greenhouse Climate Monitor

​Overview

​Architecture

​Complete Implementation

​Edge API on Raspberry Pi

​Setup (one-time)

​Edge API Code

​Run the Edge API

​Test Edge API

​Lua Agent Implementation

​src/tools/SetRelayTool.ts

​src/index.ts

​Environment Setup

​Testing

​Test Edge API Directly

​Test with Lua

​Wiring

​Production Deployment

​Run Edge API on Boot

​Key Features

Remote Control

Secure API

Scheduled Automation

Safety First

​Next IoT Demo

Greenhouse Climate Monitor

Overview

Architecture

Complete Implementation

Edge API on Raspberry Pi

Setup (one-time)

Edge API Code

Run the Edge API

Test Edge API

Lua Agent Implementation

src/tools/SetRelayTool.ts

src/index.ts

Environment Setup

Testing

Test Edge API Directly

Test with Lua

Wiring

Production Deployment

Run Edge API on Boot

Key Features

Next IoT Demo