IoT Design Methodology: Specifications & Architecture Views

Why Do We Need an IoT Design Methodology? (In Simple Words)

Building an IoT project is much more challenging than writing a simple software program in C++ or Python.

In IoT, you must work with many moving parts all at once:

• Physical electronic hardware and sensors
• Microcontrollers (like Arduino or ESP32)
• Wireless networking (Wi-Fi, Zigbee, cellular)
• Cloud databases and server APIs
• Mobile phone apps and web dashboards

If you don’t follow a clear, organized plan, you will end up with incompatible components, security bugs, and high battery consumption.

To make IoT development systematic, researchers Arshdeep Bahga and Vijay Madisetti proposed a famous 8-Step IoT Design Methodology.

1. The 8-Step IoT Design Methodology

2. Step-by-Step Practical Example: Smart Home Garden System

Let’s understand all 8 steps using a simple project: An Automatic Garden Watering System.

Step 1: Purpose & Requirements

• Purpose: Automatically check soil moisture in the home garden and turn on the water pump when the soil becomes too dry.
• Rules: Read soil moisture every 15 minutes. If moisture is below 30%, run the water pump for 5 minutes.
• Budget/Limits: Must run on a small battery and Wi-Fi, with a hardware cost under ₹1,500.

Step 2: Process Specification

Draws a clear flowchart of how the system operates step-by-step:

[ Sleep Mode (Saves Battery) ]
           │
           ▼ (Timer wakes device every 15 mins)
[ Read Soil Moisture Sensor ]
           │
           ▼
    Is Moisture < 30% ?
       ├── YES ──▶ [ Turn ON Water Pump Relay for 5 mins ] ──┐
       └── NO  ───────────────────────────────────────────────┴──▶ [ Upload Reading to Cloud ] ──▶ [ Go back to Sleep ]

Step 3: Domain Model Specification

Identifies all physical objects and virtual entities in the system:

• Physical Entities: Soil, plants, water container.
• Hardware Devices: Soil moisture sensor (YL-69), 5V Relay, ESP32 microcontroller board.
• Virtual Entities: Virtual Garden status stored in the cloud.
• Users: Homeowner checking status on an Android app.

Step 4: Information Model Specification

Defines the exact data structure and units:

• SoilMoisture: Percentage (e.g. 28%)
• PumpStatus: Boolean (true for ON, false for OFF)
• LastWateredTime: Timestamp (e.g. 2026-10-23 08:30 AM)

Step 5: Service Specifications

Defines the software APIs provided by the system:

• Status API: GET /api/garden/status (returns current moisture and pump state).
• Control API: POST /api/garden/pump (commands the pump to switch ON or OFF).

Step 6: IoT Level Specification

Decides whether data is processed locally on the microcontroller or sent to the cloud (IoT Levels 1 to 6).

3. Functional View vs. Operational View

In DAVV BCA exams, this comparison is very frequently asked:

Comparison Table for DAVV Exams:

4. Steps 7 & 8: Integration and Application Development

• Step 7 (Device & Component Integration): Connect the real hardware on a breadboard: wire the sensor to GPIO pins, add power supply, and write the Arduino C++ firmware.
• Step 8 (Application Development): Build the final user interface — creating the mobile app (Flutter / Android) and cloud dashboard with toggle switches, charts, and push notifications.

💡 DAVV Exam Preparation Tips

5-Mark Question: “Differentiate between Functional View and Operational View in IoT design.”

• Functional View: Describes the logical functions of the system (“WHAT it does” — sensing, data processing, security).
• Operational View: Describes the physical implementation (“WHERE and HOW it runs” — which microcontroller, which cloud server, which wireless protocol).
• Give simple examples for both.

5-Mark Question: “List the core steps involved in IoT Design Methodology.”

• Write all 8 steps in proper order:
  1. Purpose & Requirements
  2. Process Specification
  3. Domain Model
  4. Information Model
  5. Service Specifications
  6. IoT Level
  7. Functional & Operational Views
  8. Integration & Application Development.

10-Mark Question: “Explain the step-by-step IoT design methodology proposed by Bahga and Madisetti. Illustrate each step with a practical smart IoT application example.”

• Draw the 8-step flowchart.
• Walk through each step using the Smart Garden or Smart Streetlight example.
• Draw the Functional View vs. Operational View comparison table.
• Mention how this structured methodology prevents bugs, saves costs, and improves system security.