Assignment 2: IoT Security System with Computer Vision

Course: DE6417 Microcontrollers 2

Assessment Type: Assignment

Weighting: This assignment contributes towards the 10% allocated for Assignments/Tests.

Objective

The objective of this assignment is to design and implement a smart security system. You will interface an Arduino Uno R3 with a motion detector (HC-SR501) and a camera module (OV7670) to detect intruders. Upon detection, the system must trigger an alert and send an image to a user's Telegram account.

This advanced assignment requires you to utilize Interrupt Service Routines (ISRs) for efficient event handling and implement off-chip peripheral communication to bridge the microcontroller with an internet-connected gateway (your PC).

Learning Outcomes Assessed

This assignment provides an opportunity to demonstrate competency in the following course learning outcomes:

• LO1: Apply microcontroller hardware technology to a given application.
• LO2: Analyse and implement the operation of off-chip peripherals.
• LO5: Develop a working software solution to meet a given specification using techniques to aid testing and fault tolerance.

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Part 1: Hardware Implementation

Task Specification

You are required to assemble a security circuit with the following functionality:

1. Motion Detection: The PIR sensor interprets infrared changes and signals the MCU.
2. Image Capture: The OV7670 module captures a frame upon trigger.
3. Data Transmission: The image data is sent via UART (Serial) to a gateway.

System Overview

The complete system consists of three interconnected components working together:

1. Hardware Layer (Arduino + Sensors): The physical circuit comprising the Arduino Uno, PIR motion sensor, and OV7670 camera module. This layer is responsible for detecting motion and capturing images.
2. Firmware Layer (Arduino Sketch): The embedded C/C++ code running on the Arduino that manages interrupts, controls the camera, and handles serial communication.
3. Gateway Layer (Python Script on PC): A Python application running on your computer that receives image data via USB serial connection and forwards it to Telegram.

Setup Process Overview

To complete this assignment, you will follow these steps in order:

Step	Task	Description
1	Component Assembly	Gather all required components and verify they are functional.
2	Hardware Wiring	Connect the PIR sensor and OV7670 camera to the Arduino Uno following the pinout diagram.
3	Power Verification	Ensure the 5V and 3.3V power rails are correctly connected. The OV7670 requires 3.3V logic levels.
4	Arduino IDE Setup	Install the Arduino IDE and any required libraries for the OV7670 camera.
5	ISR Implementation	Write and test the Interrupt Service Routine for motion detection (Stage A).
6	Camera Configuration	Configure the OV7670 registers via I2C and implement the image capture routine (Stage B).
7	Serial Transmission	Implement the UART protocol to send image data to the PC.
8	Python Gateway Setup	Install Python dependencies (pyserial, requests) and create the gateway script (Stage C).
9	Telegram Bot Setup	Create a Telegram bot using BotFather and obtain your bot token and chat ID.
10	Integration Testing	Test the complete system end-to-end: motion → capture → transmit → Telegram notification.

What You Need to Deliver

By the end of this assignment, you should have:

• A fully wired hardware prototype on a breadboard
• An Arduino sketch that detects motion via interrupt and captures/transmits an image
• A Python script that receives serial data and sends images to Telegram
• A demonstration video showing the complete workflow

Required Components

• 1x Arduino Uno R3
• 1x HC-SR501 PIR Motion Sensor
• 1x OV7670 Camera Module
• 1x Breadboard & Jumper Wires
• Resistors: 2× voltage divider pairs (2.2 kΩ + 3.3 kΩ) for XCLK (D4) and RESET (D3); 2× 4.7 kΩ pull-up resistors for I²C lines (A4/A5 to 3.3 V)

Hardware Setup Notes

• PIR Sensor: Connect the PIR output to digital pin 2 or 3 on the Arduino (these are the only pins compatible with attachInterrupt on the Uno).
• OV7670 Camera: The wiring for this module can be extensive. Ensure you connect SIOC and SIOD (I2C) correctly, along with the VSYNC and PCLK synchronization pins.

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Part 2: Software Development

Stage A: Motion Detection via ISR

Implement an Interrupt Service Routine (ISR) to handle the PIR sensor trigger.

Example Code Structure:

volatile bool motionDetected = false;

void setup() {
  pinMode(2, INPUT); // PIR connected to Pin 2
  attachInterrupt(digitalPinToInterrupt(2), isr_motion, RISING);
}

void isr_motion() {
  motionDetected = true; // Set flag only
}

Stage B: Camera Interface & Image Transmission

In your main loop():

1. Check if the motionDetected flag is set.
2. If set, initialize the OV7670 capture sequence.
3. Read the pixel data from the camera.
4. Send the data via Serial.write() to your PC.
5. Reset the flag and system state.

Stage C: Telegram Integration (The Gateway)

Since the Arduino Uno lacks native internet connectivity, you will develop a gateway script in Python running on your computer.

Python Gateway Example:

# pip install pyserial requests
import serial
import requests

# 1. Setup Serial Connection
ser = serial.Serial('COM3', 115200) # Adjust 'COM3' or '/dev/tty...'

# 2. Logic loop
while True:
    if ser.in_waiting > 0:
        # [Add code to read image bytes from serial save to 'detected.jpg']
        
        # 3. Send to Telegram
        bot_token = 'YOUR_BOT_TOKEN'
        chat_id = 'YOUR_CHAT_ID'
        url = f'https://api.telegram.org/bot{bot_token}/sendPhoto'
        
        with open('detected.jpg', 'rb') as img:
            files = {'photo': img}
            requests.post(url, data={'chat_id': chat_id}, files=files)

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Implementation Requirements

• Non-Blocking Logic: Use non-blocking code where possible.
• Baud Rate: Use a high baud rate (e.g., 115200 or 1000000) to transfer image data quickly.
• Documentation: Comment your code to explain your I2C register settings for the camera.

Submission

You must submit a zip file containing:

1. Arduino Sketch (.ino): Well-commented code.
2. Gateway Script: The Python script used for the Telegram interface.
3. Demonstration Video: A short video showing the motion trigger -> Telegram notification.

Grading Rubric

Criteria	Marks	LO
Hardware Implementation Camera connections, sensor usage, logic levels, wiring quality.	20	LO1, LO2
Stage A: Interrupts (ISR) Correct use of attachInterrupt; Minimal ISR logic (flag only).	20	LO5
Stage B: Camera & Serial State machine logic; Successful image capture and transmission.	30	LO2
Stage C: Python Gateway Python serial reading; Telegram API integration.	20	LO5
Code Quality Register documentation; Non-blocking structure.	10	LO5
Total	100