NIELIT ROPAR SMART LAB – Complete Documentation

Production-Ready IoT Smart Home System for ESP8266

---

📑 Table of Contents

1. Overview
2. Features
3. Hardware Requirements
4. Software Requirements
5. Installation Guide
6. First-Time Setup
7. Web Interface Guide
8. OTA Firmware Updates
9. API Documentation
10. Physical Controls
11. Troubleshooting
12. Advanced Configuration
13. Security & Best Practices

---

🎯 Overview

NIELIT Smart Lab is a comprehensive IoT system built on ESP8266, designed for educational institutions and home automation. It provides:

• Dual relay control with web and physical interfaces
• Environmental monitoring via DHT11 sensor
• Wireless firmware updates (OTA)
• Factory reset with authentication
• Real-time system monitoring and logging

Key Improvements in v3.0.0:

• ✅ Fixed OTA Update page loading bug
• ✅ Fixed Factory Reset authentication
• ✅ Enhanced error handling
• ✅ Improved code documentation

---

✨ Features

Core Functionality

Feature	Description
Relay Control	2 independent relays (web + physical buttons)
Environmental Sensing	DHT11 temperature & humidity monitoring
WiFi Manager	Captive portal for easy network setup
OTA Updates	Upload firmware via web browser
Factory Reset	Complete device reset with password
System Logs	Real-time event tracking (20 entries)

Advanced Features

• ⚡ Rate Limiting: 20 toggles/minute per relay
• 💾 EEPROM Persistence: Saves relay states across reboots
• 🔒 HTTP Authentication: Protects admin functions
• 🌐 mDNS Support: Access via http://nielit-ropar.local
• 🐕 Watchdog Timer: Auto-recovery from crashes (8s timeout)
• 📊 Memory Monitoring: Auto-restart below 8KB free heap
• 🔊 Audio Feedback: Buzzer confirms all actions

---

🔧 Hardware Requirements

Components List

Component	Specification	Quantity	Pin Connection
ESP8266 Board	NodeMCU v3 / Wemos D1 Mini	1	-
Relay Module	2-Channel 5V (ACTIVE-HIGH)	1	D1, D2
Temperature Sensor	DHT11	1	D5
Status LEDs	5mm Red/Green	2	D7, D8
Control Buttons	Tactile Push Button	2	RX, TX
Buzzer	5V Active Buzzer	1	D3
Resistors	220Ω (for LEDs)	2	-
Power Supply	5V 2A USB/DC Adapter	1	VIN/5V
Breadboard	Half-size or full-size	1	-
Jumper Wires	Male-to-Male/Female	20+	-

Complete Pin Mapping

┌─────────────────────────────────────────────────────────┐
│              ESP8266 NodeMCU Pin Configuration           │
├─────────────┬──────────┬──────────┬────────────────────┤
│ Function    │ Board Pin│ GPIO Pin │ Connection Details │
├─────────────┼──────────┼──────────┼────────────────────┤
│ Relay 1     │ D1       │ GPIO5    │ → Relay IN1        │
│ Relay 2     │ D2       │ GPIO4    │ → Relay IN2        │
│ LED 1       │ D7       │ GPIO13   │ → 220Ω → LED → GND │
│ LED 2       │ D8       │ GPIO15   │ → 220Ω → LED → GND │
│ Button 1    │ RX       │ GPIO3    │ → Button → GND     │
│ Button 2    │ TX       │ GPIO1    │ → Button → GND     │
│ Buzzer      │ D3       │ GPIO0    │ → Buzzer+ → GND    │
│ DHT11 Data  │ D5       │ GPIO14   │ → DHT11 Data Pin   │
│ DHT11 VCC   │ 3.3V     │ -        │ → DHT11 VCC        │
│ DHT11 GND   │ GND      │ -        │ → DHT11 GND        │
│ Power In    │ VIN/5V   │ -        │ ← 5V 2A Supply     │
│ Ground      │ GND      │ -        │ ← Common Ground    │
└─────────────┴──────────┴──────────┴────────────────────┘

Wiring Diagram

                    ┌──────────────────────┐
                    │   ESP8266 NodeMCU    │
                    │                      │
    5V Power ───────┤ VIN              3V3 ├───── DHT11 VCC
    Ground ─────────┤ GND              GND ├───── Common GND
                    │                      │
    Relay IN1 ──────┤ D1  (GPIO5)       D5 ├───── DHT11 Data
    Relay IN2 ──────┤ D2  (GPIO4)       D7 ├───[220Ω]─── LED1 ─── GND
                    │                   D8 ├───[220Ω]─── LED2 ─── GND
    Button1 ────────┤ RX  (GPIO3)       D3 ├───── Buzzer+ ─── GND
    Button2 ────────┤ TX  (GPIO1)          │
                    └──────────────────────┘

    ┌──────────────────────────────────┐
    │    2-Channel Relay Module        │
    ├──────────────────────────────────┤
    │  VCC ←── 5V Power Supply         │
    │  GND ←── Common Ground           │
    │  IN1 ←── D1 (GPIO5)              │
    │  IN2 ←── D2 (GPIO4)              │
    │                                  │
    │  Relay 1: COM1 ──┬── NO1        │
    │                  └── NC1         │
    │  Relay 2: COM2 ──┬── NO2        │
    │                  └── NC2         │
    └──────────────────────────────────┘

⚠️ IMPORTANT NOTES:

• Relay Logic: ACTIVE-HIGH (HIGH = ON, LOW = OFF)
• Button Logic: ACTIVE-LOW with internal pullup (press = connect to GND)
• DHT11 Power: Use 3.3V for stability (5V can work but may cause errors)
• Common Ground: All components must share common ground with ESP8266
• Power Supply: 2A minimum to handle relay switching current

---

💻 Software Requirements

Arduino IDE Setup

1. Install Arduino IDE

• Version Required: 1.8.19 or newer
• Download: arduino.cc/en/software

2. Add ESP8266 Board Support

1. Open Arduino IDE
2. Go to File → Preferences
3. In "Additional Board Manager URLs", add:

   http://arduino.esp8266.com/stable/package_esp8266com_index.json
   

4. Click OK
5. Go to Tools → Board → Boards Manager
6. Search for esp8266
7. Install ESP8266 by ESP8266 Community (version 3.0.0+)
8. Click Close

3. Install Required Libraries

Open Sketch → Include Library → Manage Libraries and install:

Library Name	Version	Author	Purpose
WiFiManager	2.0.16+	tzapu	WiFi configuration portal
ArduinoJson	6.21.0+	Benoit Blanchon	JSON parsing for API
DHT sensor library	1.4.4+	Adafruit	DHT11 temperature/humidity
Adafruit Unified Sensor	1.1.9+	Adafruit	Required by DHT library

Built-in Libraries (No Installation Needed):

• ESP8266WiFi
• ESP8266WebServer
• ESP8266mDNS
• ESP8266HTTPUpdateServer
• EEPROM

Verify Installation

Create a test sketch:

#include <ESP8266WiFi.h>
#include <WiFiManager.h>
#include <ArduinoJson.h>
#include <DHT.h>

void setup() {
  Serial.begin(115200);
  Serial.println("Libraries loaded successfully!");
}

void loop() {}

Click Verify (✓). If it compiles without errors, you're ready!

---

📥 Installation Guide

Step 1: Connect ESP8266

1. Connect via USB to your computer
2. Wait for drivers to install (Windows: Check Device Manager)
3. Note the COM port (e.g., COM3, COM5)
   • Windows: Device Manager → Ports (COM & LPT)
   • Mac: /dev/cu.usbserial-*
   • Linux: /dev/ttyUSB*

Step 2: Configure Arduino IDE

1. Open NIELIT_SmartHome.ino
2. Go to Tools and configure:

Setting	Value
Board	NodeMCU 1.0 (ESP-12E Module)
Upload Speed	115200
CPU Frequency	80 MHz
Flash Size	4MB (FS:2MB OTA:~1019KB) ⚠️ Critical!
Port	Your COM port (e.g., COM3)
Erase Flash	Only Sketch (or "All" for first upload)
Debug Level	None

Step 3: Compile Firmware

1. Click Verify (✓) button
2. Wait for compilation (30-60 seconds)
3. Check for errors in the output window
4. Expected output:

   Sketch uses 357,232 bytes (34%) of program storage space.
   Global variables use 31,416 bytes (38%) of dynamic memory.
   

Step 4: Upload Firmware

1. Ensure ESP8266 is connected via USB
2. Click Upload (→) button
3. Monitor progress in the output window:

   Uploading...
   Writing at 0x00000000... (10%)
   Writing at 0x00004000... (20%)
   ...
   Writing at 0x00074000... (100%)
   Hard resetting via RTS pin...
   

4. Success message: Done uploading.

Step 5: Verify Upload

⚠️ IMPORTANT: Serial Monitor is DISABLED in this firmware due to use of RX/TX pins for physical buttons!

Instead, verify upload by:

1. Audio feedback:
   • 3 beeps = Fresh boot (no saved state)
   • 2 beeps = State restored from EEPROM
2. LED indicators:
   • LEDs should be OFF (or match last saved state)
3. WiFi network:
   • Look for NIELIT-SmartLab WiFi network (AP mode)

Why No Serial Monitor?

• GPIO3 (RX) and GPIO1 (TX) are used for physical buttons
• Serial communication would interfere with button detection
• All diagnostics available via web interface (/logs page)

---

🚀 First-Time Setup

WiFi Configuration Process

When powered on for the first time, the device enters Access Point (AP) Mode:

Audio/Visual Indicators

Beep Pattern	Meaning
3 beeps	Fresh boot (no EEPROM data)
4 beeps	AP mode activated
1 beep	WiFi connected successfully
2 beeps	State restored from EEPROM

Step-by-Step WiFi Setup

Step 1: Power ON Device

▪️ Connect 5V power supply
▪️ Wait 3-5 seconds for boot
▪️ Listen for 4 beeps (AP mode active)

Step 2: Connect to AP

📱 On your phone/laptop:
   └─ WiFi Settings
      └─ Select: NIELIT-SmartLab
         └─ Password: nielit2025

Step 3: Configure WiFi

🌐 Captive portal opens automatically
   (If not, browse to: http://192.168.4.1)

   1. Click "Configure WiFi"
   2. Select your home WiFi network
   3. Enter WiFi password
   4. Click "Save"

Step 4: Wait for Connection

⏳ Device will:
   1. Save credentials to memory
   2. Reboot automatically
   3. Connect to your WiFi
   4. Beep once (success)

Step 5: Find Device IP

Since Serial Monitor is disabled, use:

Option A: Router Admin Panel
   └─ DHCP Client List
      └─ Look for "ESP_XXXXXX" or "NIELIT-SmartLab"

Option B: mDNS (if supported)
   └─ Browse to: http://nielit-ropar.local

Option C: Network Scanner App
   └─ Use: Fing (iOS/Android) or Advanced IP Scanner (Windows)
      └─ Scan for device on port 80

Troubleshooting First Setup

Problem	Solution
Can't see AP network	• Power cycle device • Check 2.4GHz WiFi enabled • Move closer to device
Captive portal doesn't open	• Manually go to 192.168.4.1 • Disable mobile data • Try different browser
Can't connect to home WiFi	• Verify password (case-sensitive) • Check router is 2.4GHz • Ensure DHCP is enabled
No beep after save	• Wait 30 seconds • Check power supply (2A needed) • Try factory reset

---

🌐 Web Interface Guide

Accessing Dashboard

Primary Methods:

🔗 http://DEVICE_IP_ADDRESS
   Example: http://192.168.1.100

🔗 http://nielit-ropar.local (mDNS)
   Note: May not work on all networks

Default Credentials:

👤 Username: admin
🔐 Password: rccrcc

Dashboard Layout

╔════════════════════════════════════════════════════════╗
║            NIELIT Ropar Smart Lab                      ║
║         Firmware v3.0.0 • ● Online                     ║
╠════════════════════════════════════════════════════════╣
║  [RELAY CONTROL]                                       ║
║  ┌────────────────────────────────────────────┐       ║
║  │ Relay 1              [ON]  [Turn OFF]      │       ║
║  │ Relay 2              [OFF] [Turn ON]       │       ║
║  └────────────────────────────────────────────┘       ║
╠════════════════════════════════════════════════════════╣
║  [ENVIRONMENT SENSORS]                                 ║
║  ┌─────────────────┬─────────────────┐                ║
║  │  Temperature    │    Humidity     │                ║
║  │     28.5°C      │      65.2%      │                ║
║  └─────────────────┴─────────────────┘                ║
╠════════════════════════════════════════════════════════╣
║  [SYSTEM INFO]                                         ║
║  Uptime:      2h 15m                                   ║
║  IP Address:  192.168.1.100                            ║
║  Free Heap:   28.5 KB                                  ║
║  Local URL:   http://nielit-ropar.local/               ║
╠════════════════════════════════════════════════════════╣
║  [FACTORY RESET]                                       ║
║  [ Factory Reset (Erase Wi-Fi & Settings) ]            ║
║  ⚠️ Requires password: admin / ******                  ║
╠════════════════════════════════════════════════════════╣
║  © NIELIT Ropar 2025 • OTA Update • System Logs       ║
╚════════════════════════════════════════════════════════╝

Dashboard Features Explained

1. Relay Control Section

Relay Status Badge:

• 🟢 ON (Green) = Relay is active
• 🔴 OFF (Red) = Relay is inactive

Control Buttons:

• Turn ON = Activates relay (green button)
• Turn OFF = Deactivates relay (red button)

Rate Limiting:

• Maximum: 20 toggles per minute per relay
• Counter resets every 60 seconds
• Exceeded limit shows error message

Audio Feedback:

• Single beep = Toggle successful
• No beep = Rate limit exceeded

2. Environment Sensors

Temperature Display:

• Range: -40°C to 80°C
• Updates every 5 seconds
• Shows -- if sensor error

Humidity Display:

• Range: 0% to 100%
• Updates every 5 seconds
• Shows -- if sensor error

3. System Information

Uptime:

• Format: Xd Yh Zm (days, hours, minutes)
• Example: 2d 5h 30m
• Resets on device reboot

IP Address:

• Shows current local IP
• Click to copy (depends on browser)

Free Heap:

• Current available RAM
• Should stay above 8 KB
• Auto-restart if below 8 KB

Local URL:

• mDNS address (if supported)
• Alternative to IP address

4. Factory Reset

Function:

• Clears all WiFi credentials
• Erases EEPROM data
• Resets to factory defaults
• Reboots into AP mode

Process:

1. Click "Factory Reset" button
2. Confirm warning dialog
3. Enter username: admin
4. Enter password: rccrcc
5. Wait 5-10 seconds for reboot

System Logs Page

Access: http://DEVICE_IP/logs

Features:

• Shows last 20 system events
• Auto-refreshes every 3 seconds
• Includes timestamps (in seconds since boot)
• No authentication required

Example Log Entries:

15s: System boot – NIELIT ROPAR v3.0.0
17s: EEPROM invalid or empty - using defaults
20s: DHT11 sensor initialized
25s: WiFi connected: 192.168.1.100
26s: mDNS started: nielit-ropar.local
27s: Web server started on port 80
28s: System ready – All services running
45s: Relay1 → ON
50s: Relay2 → ON

---

🔄 OTA Firmware Updates

Preparing for OTA Update

Step 1: Generate .BIN File

Using Arduino IDE:

1. Open your modified NIELIT_SmartHome.ino
2. Increment version if you made changes:

   #define FIRMWARE_VERSION "3.0.1"  // Change from 3.0.0

3. Go to: Sketch → Export Compiled Binary
   • Or press Ctrl+Alt+S (Windows/Linux)
   • Or press Cmd+Alt+S (Mac)
4. Wait for compilation (output shows "Done")
5. Locate .BIN file:
   • Windows: Documents\Arduino\NIELIT_SmartHome\
   • Mac: ~/Documents/Arduino/NIELIT_SmartHome/
   • Linux: ~/Arduino/NIELIT_SmartHome/
   • Filename: NIELIT_SmartHome.ino.nodemcu.bin

Verify .BIN File:

✅ File size: 350-450 KB
✅ Extension: .bin
✅ No spaces in filename (if renaming)

Step 2: Perform OTA Update

Access Update Page:

🔗 http://DEVICE_IP/update
   Example: http://192.168.1.100/update

🔗 http://nielit-ropar.local/update

Update Process:

┌──────────────────────────────────────────┐
│        OTA Update – NIELIT ROPAR         │
│                                          │
│  Current: v3.0.0                         │
│                                          │
│  [Password: ******]                      │
│  [Choose .bin File]                      │
│                                          │
│  ⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜ 0%                     │
│                                          │
│  [Update Firmware] (disabled)            │
│                                          │
│  © NIELIT ROPAR 2025 • Back to Dashboard │
└──────────────────────────────────────────┘

Steps:

1. Enter password: rccrcc
2. Click "Choose .bin File"
3. Select your .bin file
4. Click "Update Firmware"
5. Monitor progress bar
6. Wait for success message
7. Device reboots automatically (20-30 seconds)
8. Verify new version on dashboard

Upload Progress:

⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜ 0%   → Starting upload...
⬛⬛⬛⬜⬜⬜⬜⬜⬜⬜ 25%  → Uploading...
⬛⬛⬛⬛⬛⬛⬜⬜⬜⬜ 50%  → Halfway there...
⬛⬛⬛⬛⬛⬛⬛⬛⬛⬜ 75%  → Almost done...
⬛⬛⬛⬛⬛⬛⬛⬛⬛⬛ 100% → ✅ Success! Rebooting...

OTA Update Troubleshooting

Error	Cause	Solution
"Authentication failed"	Wrong password	Use rccrcc exactly
"Only .bin files allowed"	Wrong file type	Export compiled binary, not .ino
"Upload failed"	Network issue	Move closer to router, retry
"Not enough space"	Wrong flash settings	Recompile with 4MB OTA partition
Page doesn't load	Browser cache	Hard refresh (Ctrl+F5)
Device unresponsive	Bad firmware	Recover via USB upload

Recovery from Bad OTA

If device becomes unresponsive:

1. Connect via USB
2. Open Arduino IDE
3. Select correct COM port
4. Upload working firmware (normal upload method)
5. Wait for upload to complete
6. Perform factory reset (web interface or via code)

Why OTA might fail:

• ❌ Wrong board type selected during compilation
• ❌ Flash size mismatch (must have OTA partition)
• ❌ Corrupted .bin file
• ❌ Power loss during upload
• ❌ WiFi connection dropped mid-upload

---

📡 API Documentation

Overview

All API endpoints return JSON responses and use RESTful conventions.

Base URL: http://DEVICE_IP/api/

Authentication: Required for /factory-reset only (HTTP Basic Auth)

Endpoints Reference

GET /api/status

Description: Retrieve current system status

Authentication: None

Response:

{
  "version": "3.0.0",
  "r1": true,
  "r2": false,
  "temp": 28.5,
  "hum": 65.2,
  "uptime": 125430,
  "ip": "192.168.1.100",
  "heap": 28672
}

Response Fields:

Field	Type	Description
version	string	Firmware version
r1	boolean	Relay 1 state (true=ON)
r2	boolean	Relay 2 state (true=ON)
temp	float	Temperature in Celsius
hum	float	Relative humidity (%)
uptime	integer	Milliseconds since boot
ip	string	Device IP address
heap	integer	Free heap in bytes

Example cURL:

curl http://192.168.1.100/api/status

---

GET /api/logs

Description: Retrieve system event logs

Authentication: None

Response:

{
  "logs": [
    "15s: System boot – NIELIT ROPAR v3.0.0",
    "20s: WiFi connected: 192.168.1.100",
    "45s: Relay1 → ON",
    "50s: Relay2 → OFF",
    ""
  ]
}

Response Fields:

• logs: Array of 20 log entries (oldest first)
• Empty strings indicate unused buffer slots

Example cURL:

curl http://192.168.1.100/api/logs

---

GET /api/relay1/on

Description: Turn Relay 1 ON

Authentication: None

Response: 303 redirect to / (dashboard)

Rate Limit: 20 toggles/minute

Error Response (429):

Rate limit exceeded: Max 20 toggles/min

Example cURL:

curl http://192.168.1.100/api/relay1/on

---

GET /api/relay1/off

Description: Turn Relay 1 OFF

Authentication: None

Response: 303 redirect to / (dashboard)

Example cURL:

curl http://192.168.1.100/api/relay1/off

---

GET /api/relay2/on

Description: Turn Relay 2 ON

Authentication: None

Response: 303 redirect to / (dashboard)

Example cURL:

curl http://192.168.1.100/api/relay2/on

---

GET /api/relay2/off

Description: Turn Relay 2 OFF

Authentication: None

Response: 303 redirect to / (dashboard)

Example cURL:

curl http://192.168.1.100/api/relay2/off

---

GET /api/reset

Description: Soft reset (clears EEPROM only, keeps WiFi)

Authentication: None

Response:

<h2>Resetting device... © NIELIT ROPAR</h2>

Effect:

• Clears EEPROM data
• Keeps WiFi credentials
• Reboots device

Example cURL:

curl http://192.168.1.100/api/reset

---

GET /api/factory-reset

Description: Complete factory reset (WiFi + EEPROM)

Authentication: HTTP Basic Auth (admin / rccrcc)

Response:

{
  "status": "success",
  "message": "Factory reset complete. Rebooting into AP mode..."
}

Effect:

• Clears EEPROM data
• Erases WiFi credentials
• Reboots into AP mode
• Audio: 5 beeps before reboot

Example cURL:

curl -u admin:rccrcc http://192.168.1.100/api/factory-reset

Error Response (401):

Authentication required

---

API Usage Examples

Python Example

import requests

BASE_URL = "http://192.168.1.100/api"

# Get status
response = requests.get(f"{BASE_URL}/status")
data = response.json()
print(f"Temperature: {data['temp']}°C")
print(f"Relay 1: {'ON' if data['r1'] else 'OFF'}")

# Toggle relay
requests.get(f"{BASE_URL}/relay1/on")

# Factory reset (requires auth)
requests.get(
    f"{BASE_URL}/factory-reset",
    auth=('admin', 'rccrcc')
)

JavaScript Example

// Get status
fetch('http://192.168.1.100/api/status')
  .then(r => r.json())
  .then(d => {
    console.log(`Temperature: ${d.temp}°C`);
    console.log(`Relay 1: ${d.r1 ? 'ON' : 'OFF'}`);
  });

// Toggle relay
fetch('http://192.168.1.100/api/relay1/on');

// Factory reset (with auth)
fetch('http://192.168.1.100/api/factory-reset', {
  method: 'GET',
  headers: {
    'Authorization': 'Basic ' + btoa('admin:rccrcc')
  }
});

---

🔐 Security Features

• HTTP Basic Authentication for OTA updates and factory reset
• Rate Limiting prevents relay abuse (20 toggles/min)
• Input Validation for all API endpoints
• WiFi Encryption with configurable AP password

---

---

🛠️ Troubleshooting

🔴 First Boot Issues

Device Stuck in AP Mode

Symptoms: Can't connect to home WiFi, keeps showing NIELIT-SmartLab network

• Solution 1: Reset WiFi credentials
  • Access device via AP mode (NIELIT-SmartLab / nielit2025)
  • Open http://192.168.4.1
  • Reconfigure WiFi with correct credentials
• Solution 2: Factory reset
  • Power off device
  • Press and hold Button 1
  • Power on while holding (release after 5 seconds)
  • Device resets to AP mode

Can't Find AP Network

• Check: WiFi is enabled on your phone/laptop
• Check: You're within 10m of the device
• Check: 2.4GHz WiFi is supported (5GHz won't work)
• Try: Restart the device (power cycle)

Captive Portal Doesn't Open

• Manual access: Open browser and go to http://192.168.4.1
• Disable mobile data: Turn off cellular data on phone
• Try different browser: Use Chrome/Firefox instead of in-app browsers

---

🌐 WiFi Connection Problems

Device Not Connecting to Home WiFi

• Verify: SSID and password are correct (case-sensitive)
• Check: Router is 2.4GHz capable (ESP8266 doesn't support 5GHz)
• Check: Router allows new device connections (not MAC filtered)
• Try: Move device closer to router
• Reset: Hold power button for 10+ seconds to force AP mode

Lost IP Address / Can't Access Web Interface

1. Check Serial Monitor for IP address (115200 baud)
2. Use mDNS: http://nielit-ropar.local
3. Check router's DHCP client list
4. Use IP scanner app (Fing, Advanced IP Scanner)

---

⚙️ Hardware Issues

Relays Not Responding

• Rate Limit: Wait 60 seconds if you hit 20 toggles/minute limit
• Power Check: Verify relay module has separate 5V supply
• Wiring Check:
  • Relay 1 → D1 (GPIO5)
  • Relay 2 → D2 (GPIO4)
  • Common ground between ESP8266 and relay module
• Test: Use physical buttons to rule out software issues
• Logs: Check /logs page for error messages

Physical Buttons Not Working

• Wiring Check:
  • Button 1 → RX (GPIO3) → Ground
  • Button 2 → TX (GPIO1) → Ground
• Note: Buttons are ACTIVE-LOW (press connects to GND)
• Test: Buttons should trigger audio feedback (beep)
• Warning: RX/TX buttons may interfere with Serial Monitor during boot

DHT Sensor Shows -- or Invalid Data

• Wiring Verification:

  DHT11 VCC  → 3.3V (NOT 5V for stability)
  DHT11 GND  → GND
  DHT11 DATA → D5 (GPIO14)
  

• Pull-up Resistor: Add 10kΩ resistor between DATA and VCC if using raw DHT11
• Wait Time: Sensor needs 2 seconds after boot to stabilize
• Test: Replace with known-good DHT11 module
• Valid Range: Temperature: -40°C to 80°C, Humidity: 0-100%

LEDs Not Illuminating

• Check: LED polarity (long leg = anode = positive)
• Resistor: Use 220Ω-330Ω current-limiting resistor
• Pins: LED1 → D7 (GPIO13), LED2 → D8 (GPIO15)
• Note: LEDs mirror relay states (ON = HIGH = lit)

Buzzer Not Working

• Type: Use ACTIVE buzzer (built-in oscillator)
• Pin: Connect to D3 (GPIO0)
• Polarity: Red/+ to GPIO0, Black/- to GND
• Test: Should beep on boot and button presses

---

🔄 OTA Update Problems

OTA Page Not Loading

• Clear Cache: Force refresh (Ctrl+F5 or Cmd+Shift+R)
• Try: Use incognito/private browsing mode
• Direct URL: http://YOUR_IP/update
• Check: Firmware version in code is v3.0.0+ (older versions had bug)

Authentication Failed

• Credentials:

  Username: admin
  Password: rccrcc
  

• Case Sensitive: Enter exactly as shown
• Browser: Avoid auto-fill, type manually

Upload Fails / Device Unresponsive

• File Check: Ensure .bin file is for ESP8266 (not ESP32)
• Size Check: File should be 300-500 KB
• Flash Size: Compiled with correct settings (4MB with OTA partition)
• WiFi: Ensure stable connection during upload (stay within 5m of router)
• Recovery: If device becomes unresponsive:
  1. Power off
  2. Connect via USB
  3. Upload firmware via serial (not OTA)

"Not Enough Space" Error

• Flash Settings: Recompile with: 4MB (FS:2MB OTA:~1019KB)
• Clear EEPROM: Use factory reset before OTA update
• Last Resort: Re-upload via USB with "Erase Flash: All Flash Contents"

---

🔄 System Behavior Issues

Device Keeps Rebooting

• Serial Monitor: Check for error messages
• Memory: Low heap warning? (check /api/status → heap)
• Power Supply: Insufficient current (need 2A minimum)
• Watchdog: Triggering due to blocked operations (check logs)
• Fix: Factory reset and re-upload firmware

Relay States Not Persisting

• EEPROM Check: Look for "State saved to EEPROM" in logs
• Fix: Perform soft reset (/api/reset)
• Verify: Check state.magic value in logs (should be 0xAA)

High Rate Limit Warnings

• Normal: Max 20 toggles per relay per minute
• Counter Reset: Automatically resets every 60 seconds
• Workaround: Wait 1 minute or perform soft reset
• Check: Review /logs for excessive toggle attempts

---

📱 Mobile/Browser Issues

Dashboard Not Auto-Updating

• JavaScript: Ensure JS is enabled in browser
• Console: Check browser console (F12) for errors
• Network: Verify /api/status endpoint returns valid JSON
• Try: Hard refresh or clear browser cache

Factory Reset Button Doesn't Work

• Authentication: Must enter credentials in popup
  • Username: admin
  • Password: rccrcc
• Confirmation: Must click "OK" in confirmation dialog
• Browser: Some browsers block popups - check for blocked popup icon
• Manual Method: Use API endpoint with curl:

  curl -u admin:rccrcc http://YOUR_IP/api/factory-reset

---

🔍 Diagnostic Tools

Serial Monitor Output

Access: Tools → Serial Monitor (115200 baud) Useful Commands: Look for:

• Boot messages with version number
• IP address assignment
• Error messages
• EEPROM state
• Relay toggle events

System Logs Page

Access: http://YOUR_IP/logs

• Shows last 20 events
• Auto-refreshes every 3 seconds
• Includes timestamps
• Helps diagnose issues without USB connection

Status API Endpoint

Access: http://YOUR_IP/api/status Returns:

{
  "version": "3.0.0",
  "r1": true,
  "r2": false,
  "temp": 28.5,
  "hum": 65.2,
  "uptime": 125430,
  "ip": "192.168.1.100",
  "heap": 28672  ← Monitor this for memory issues
}

---

🆘 Emergency Recovery

Complete Factory Reset (Nuclear Option)

1. Via Web Interface:

   • Go to dashboard
   • Scroll to "Factory Reset" section
   • Enter credentials (admin / rccrcc)
   • Confirm reset
   • Wait for reboot into AP mode

2. Via API (if web interface not working):

   curl -u admin:rccrcc http://YOUR_IP/api/factory-reset

3. Hardware Method (if completely unresponsive):

   • Power off device
   • Connect to computer via USB
   • In Arduino IDE: Tools → Erase Flash → All Flash Contents
   • Re-upload firmware
   • Reconfigure WiFi from scratch

Recovering from Bad OTA Update

1. Connect device via USB
2. Open Arduino IDE
3. Upload working firmware via serial
4. Check Serial Monitor for errors
5. Perform factory reset if needed

---

📖 Advanced Configuration

Customizing Device Settings

You can modify these constants in the firmware before uploading:

// In NIELIT_SmartHome.ino

#define DEVICE_NAME      "NIELIT-SmartLab"   // AP name and mDNS hostname
#define AP_PASSWORD      "nielit2025"         // AP mode password
#define ADMIN_USER       "admin"              // Web interface username
#define ADMIN_PASS       "rccrcc"             // Web interface password

#define MAX_TOGGLES_PER_MIN      20          // Rate limit per relay
#define DHT_UPDATE_INTERVAL      5000        // Sensor read interval (ms)
#define MIN_FREE_HEAP            8192        // Auto-restart threshold (bytes)

After making changes:

1. Save the file
2. Recompile and upload via USB or OTA
3. Device will use new settings after reboot

---

🔌 Wiring Diagram

Complete Hardware Setup

┌─────────────────────────────────────────────────────────────┐
│                     ESP8266 NodeMCU                          │
│                                                              │
│  3V3 ●────────────● VCC (DHT11)                             │
│  GND ●────────────● GND (DHT11, Relay, LEDs, Buzzer)       │
│                                                              │
│   D1 ●────────────● IN1 (Relay Channel 1)                  │
│   D2 ●────────────● IN2 (Relay Channel 2)                  │
│                                                              │
│   D5 ●────────────● DATA (DHT11)                            │
│                                                              │
│   D7 ●────[220Ω]──● LED1 (Anode) → Cathode to GND         │
│   D8 ●────[220Ω]──● LED2 (Anode) → Cathode to GND         │
│                                                              │
│   D3 ●────────────● BUZZER (+) → BUZZER (-) to GND        │
│                                                              │
│   RX ●────[BTN1]──● GND (Press to toggle Relay 1)         │
│   TX ●────[BTN2]──● GND (Press to toggle Relay 2)         │
│                                                              │
│  VIN ●────────────● 5V Power Supply                         │
│  GND ●────────────● Power Supply GND                        │
└─────────────────────────────────────────────────────────────┘

┌─────────────────────────────────────────────────────────────┐
│                    2-Channel Relay Module                    │
│                                                              │
│  VCC ●────────────● 5V Power Supply                         │
│  GND ●────────────● Common GND with ESP8266                 │
│  IN1 ●────────────● From D1 (GPIO5)                         │
│  IN2 ●────────────● From D2 (GPIO4)                         │
│                                                              │
│  COM1 ●───────────● AC/DC Load Common                       │
│  NO1  ●───────────● AC/DC Load (Normally Open)              │
│  NC1  ●   (unused - Normally Closed)                        │
│                                                              │
│  COM2 ●───────────● AC/DC Load Common                       │
│  NO2  ●───────────● AC/DC Load (Normally Open)              │
│  NC2  ●   (unused - Normally Closed)                        │
└─────────────────────────────────────────────────────────────┘

⚠️ SAFETY WARNING:
- Never work on AC circuits while powered
- Use proper insulation and enclosures
- Follow local electrical codes
- Test with low voltage loads first (LED strips, DC fans)

Pin Mapping Summary

Function	ESP8266 Pin	GPIO	Notes
Relay 1	D1	GPIO5	Output (ACTIVE-HIGH)
Relay 2	D2	GPIO4	Output (ACTIVE-HIGH)
LED 1	D7	GPIO13	Mirrors Relay 1 state
LED 2	D8	GPIO15	Mirrors Relay 2 state
Button 1	RX	GPIO3	Input (ACTIVE-LOW)
Button 2	TX	GPIO1	Input (ACTIVE-LOW)
Buzzer	D3	GPIO0	Output (ACTIVE-HIGH)
DHT11	D5	GPIO14	Data pin

---

🔐 Security Best Practices

Change Default Credentials

Before deploying in production:

1. Modify credentials in code:

   #define ADMIN_USER       "your_username"
   #define ADMIN_PASS       "your_strong_password"
   #define AP_PASSWORD      "your_ap_password"

2. Use strong passwords:

   • Minimum 8 characters
   • Mix of letters, numbers, symbols
   • Avoid common words

Network Security

• Use WPA2/WPA3 encryption on your WiFi router
• Change AP password from default nielit2025
• Disable AP mode after initial setup (requires code modification)
• Use VPN if accessing from outside local network
• Firewall rules to restrict access to device IP

Firmware Security

• Verify .bin files before OTA updates
• Keep backups of working firmware versions
• Test updates on development device first
• Monitor logs for unauthorized access attempts

---

📊 Performance Specifications

Metric	Value
Boot Time	~5-8 seconds (WiFi dependent)
Web Response Time	<100ms (local network)
Relay Switching Speed	<50ms
DHT Update Rate	Every 5 seconds
API Rate Limit	20 toggles/min per relay
Max Concurrent Users	4-5 (limited by ESP8266 RAM)
Memory Usage (Idle)	~25-30 KB free heap
Power Consumption	~80mA (idle), ~250mA (relays ON)
WiFi Range	~30m (indoor, 2.4GHz)
OTA Update Time	30-60 seconds

---

🎯 Use Cases

Home Automation

• Smart Lighting: Control room lights remotely
• Fan Control: Automated temperature-based fan control
• Appliance Scheduling: Timer-based device control
• Environmental Monitoring: Track room temperature/humidity

Educational Projects

• IoT Learning: Hands-on ESP8266 programming
• Web Development: REST API and frontend integration
• Electronics: Relay control and sensor interfacing
• Network Protocols: WiFi, HTTP, mDNS, OTA

Laboratory Management

• Equipment Control: Remote lab equipment switching
• Climate Monitoring: Temperature/humidity logging
• Access Control: Authenticated remote operation
• Energy Management: Monitor device states and uptime

---

v3.0.0 (2025-01-29)

• ✅ Fixed OTA Update page loading issue (PROGMEM handling)
• ✅ Fixed Factory Reset authentication and execution
• ✅ Improved code documentation and readability
• ✅ Enhanced error handling for web endpoints

v2.0.0

• Added factory reset functionality
• Improved memory management
• Enhanced logging system

v1.0.0

• Initial production release
• Core relay and sensor functionality

---

📄 License

MIT License – © NIELIT ROPAR 2025

---

🤝 Support

Developed by: Lovnish Verma

Contact: princelv84@gmail.com

Documentation: Wiki

For bug reports and feature requests, please open an issue on GitHub.

---

⭐ Acknowledgments

Built with:

• ESP8266 Arduino Core
• WiFiManager by tzapu
• ArduinoJson by Benoit Blanchon
• DHT Sensor Library by Adafruit
• NOCE MCU Blynk board

📄 Screenshots

---

---

The hardware used includes a NOCE MCU Blynk board, an ESP8266, one buzzer, two LEDs, some resistors, and connecting wires.