# ⚙️ Hardware Documentation

## 🧩 Used Components

- **Arduino Mega 2560**  
  Main control microcontroller responsible for reading all sensors and controlling the motors.  
  - Large memory and many I/O pins compared to Arduino Uno  
  - Handles sensor fusion, obstacle avoidance, and communicates with Raspberry Pi  

- **Raspberry Pi Zero 2**  
  - Processes camera data (line / object detection)  
  - Sends simplified results to Arduino over serial (115200 baud)  
  - Offloads heavy tasks (image recognition) from Arduino  

- **Adafruit Motor Shield V2**  
  - Motor driver shield, controls DC motor via I2C  
  - Provides PWM speed regulation, H-bridge for direction control  
  - Leaves most Arduino pins free  

- **TOF Sensors (VL53L1X)**  
  - Millimeter-accurate time-of-flight sensors  
  - **Front sensor** → obstacle detection  
  - **Side sensors** → track centering  
  - More precise and reliable than ultrasonic sensors  

- **IMU (gyro + accelerometer)**  
  - Added as fallback when two ToFs burned out  
  - Provides yaw/orientation feedback  
  - Used together with side ToFs for stable turns  

- **Color Sensor (TCS34725)**  
  - Reads RGB + clear light via I2C  
  - Used to **detect and count orange & blue lines** on the track  
  - Essential for lap counting and checkpoints  

- **Servo Motor (SG90)**  
  - Controls front steering mechanism  
  - PWM control from Arduino  
  - Software-limited range to prevent oversteering  

- **DC Motor**  
  - Drives the robot forward/backward  
  - Controlled through Motor Shield with PWM  
  - Gear reduction for torque & smoother motion  
  - Bearings used in drivetrain for efficiency  

- **Li-ion Batteries**  
  - Power Arduino, Motor Shield, motors, and sensors  
  - High energy density & rechargeability  

- **Power Bank**  
  - Dedicated 5V supply for Raspberry Pi  
  - Isolates Pi from motor power spikes  

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## 🔀 Configurations

### Variant A – Without IMU (5× ToF)
- 5× VL53L1X on I²C bus (unique addresses via XSHUT).  
- Front ToF → obstacle detection.  
- Four side ToFs → distance and angle measurement.  
- Pure geometry-based alignment.  

### Variant B – With IMU (3× ToF + IMU)
- 3× VL53L1X on I²C bus.  
- IMU on same I²C bus for yaw/orientation.  
- Side ToFs still used for Δx calculation.  
- IMU yaw stabilizes turns, compensates for missing sensors.  
- Same PD algorithm, only input sources changed.  

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## 🔌 Wiring Diagram (textual)

- **Arduino Mega ↔ Motor Shield V2**: I²C bus  
- **DC Motor** → Motor Shield **M1**  
- **Servo Motor** → Arduino **D9 (PWM)**  
- **TOF Sensors (VL53L1X)** → I²C (SDA, SCL), **XSHUT** pins to digital pins for addressing  
- **IMU** → I²C (SDA, SCL), optional INT pin to digital input  
- **Color Sensor (TCS34725)** → I²C (same bus)  
- **Li-ion Battery Pack** → Arduino Mega + Motor Shield  
- **Raspberry Pi Zero 2** ↔ Arduino Mega → Serial (TX/RX, 115200 baud)  
- **Raspberry Pi Camera** → Pi camera port  
- **Power Bank → Raspberry Pi** (stable 5V supply)  

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## 🛠️ Component Selection Justification

- **Arduino Mega** → many peripherals at once, strong I/O support  
- **Raspberry Pi Zero 2** → dedicated vision processor, avoids overloading Arduino  
- **Motor Shield V2** → reliable I²C control, PWM, H-bridges included  
- **TOF sensors** → accurate, fast, unaffected by surface angles (better than ultrasonic)  
- **IMU** → essential fallback orientation, low-cost redundancy  
- **Servo motor** → accurate steering vs DC continuous motors  
- **DC motor w/ gear reduction** → torque + smooth control  
- **Li-ion + Power bank separation** → isolates Pi from noisy motor voltage  

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## 📦 Hardware Expansion Possibilities

- Add **wheel encoders** → closed-loop speed & distance tracking  
- Add **current sensors** → detect stalls / overload  
- Add **battery monitoring** → prevent low-voltage damage  
- Upgrade to **Raspberry Pi 4** → enable advanced vision (object detection, SLAM)  
- Add **Wi-Fi / Bluetooth** → for remote debugging & telemetry  

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## 📑 Schematics

- [Without IMU (5× ToF)](../schemes/Without%20IMU.pdf)  
- [With IMU (3× ToF + IMU)](../schemes/with%20IMU.pdf)