🚗 ESP32 RC Car with PS4 Controller

A feature-rich RC car built with ESP32, controlled via PS4 DualShock controller over Bluetooth. Includes advanced lighting system, trip computer, battery monitoring, and real-time telemetry.

📋 Table of Contents

• Hardware Specifications
• Functional Features
• Wiring Diagram
• Software Architecture
• Building and Uploading
• Controls
• Display System
• Troubleshooting
• Development

🔧 Hardware Specifications

Main Components

• Microcontroller: ESP32-WROOM-32 Development Board
• Motors: 2× DC Geared Motors with Quadrature Encoders (3638 counts/rev)
• Motor Driver: L298N-compatible Dual H-Bridge
• Servo: Standard servo motor for steering (controlled via PCA9685)
• Display: 128×64 SSD1306 OLED (I2C)
• PWM Driver: PCA9685 16-Channel PWM Driver (I2C)
• Battery: Conrad Energy 20C 3700mAh 7.4V LiPo
• Lighting: 8× LEDs (4× White headlights, 4× Red tail lights)

Power Consumption

• Idle: ~360mA
• Normal Driving: ~1.75A
• Aggressive Driving: ~2.55A
• Battery Life: 1.5-2+ hours continuous driving

Physical Specifications

• Wheel Circumference: 0.2199m (calibrated)
• Encoder Resolution: 3638 counts per revolution
• Servo Range: 50°-130° (mechanically limited)
• Maximum Speed: Variable (PID controlled)

⚡ Functional Features

🎮 Control System

• Wireless Control: PS4 DualShock controller via Bluetooth HID
• Auto-reconnection: Automatic connection recovery
• Safety Systems: Motor stop on connection loss
• Connection Health Monitoring: Real-time connection status

🚗 Driving Features

• Differential Drive: Independent left/right motor control
• PID Motor Control: Precise speed regulation
• Encoder Feedback: Real-time speed and distance measurement
• Multiple Drive Modes: Normal, High-speed, Direct control, Diagnostics

💡 Advanced Lighting System

• 4-Pin Independent Control: Separate left/right headlights and tail lights
• Automatic Turn Signals: Activated by steering input (±100 threshold)
• Brake Lights: Automatic activation on brake trigger (>50)
• Headlight Flashing: 2-second flash sequence (5Hz)
• Smart Priority System: Flashing → Turn Signals → Brake Lights → Normal

📊 Trip Computer

• 4-Page Navigation: Total ODO, Trip 1, Trip 2, Current Trip
• Persistent Storage: NVS-based odometry storage
• Distance Formatting: Automatic m/km conversion
• Trip Reset: Hold D-pad DOWN for 3 seconds
• Circular Navigation: D-pad LEFT/RIGHT page switching

🔋 Battery Management

• Real-time Monitoring: ADC-based voltage measurement
• Voltage Divider: 4:1 ratio (3× 10kΩ resistors)
• Percentage Display: 6.4V-8.8V range mapping
• Filtered Readings: Stable battery percentage calculation
• Visual Indicator: Top-right corner percentage display

🖥️ Display System

• Startup Screen: Battery%, Bluetooth status, Total ODO
• Trip Computer: 4-page odometry with navigation dots
• Status Icons: Bluetooth, LED status, turn signals
• Real-time Updates: 1-second refresh rate

🔌 Wiring Diagram

ESP32 Pin Configuration

GPIO 15 → Left Headlights (2× White LEDs + 220Ω resistors)
GPIO 4  → Right Headlights (2× White LEDs + 220Ω resistors)
GPIO 16 → Left Tail Lights (2× Red LEDs + 220Ω resistors)
GPIO 17 → Right Tail Lights (2× Red LEDs + 220Ω resistors)

GPIO 18 → Left Motor PWM
GPIO 19 → Left Motor INA
GPIO 13 → Left Motor INB
GPIO 5  → Right Motor PWM
GPIO 23 → Right Motor INA
GPIO 12 → Right Motor INB

GPIO 25 → Left Encoder A
GPIO 26 → Left Encoder B
GPIO 14 → Right Encoder A
GPIO 27 → Right Encoder B

GPIO 21 → I2C SDA (OLED + PCA9685)
GPIO 22 → I2C SCL (OLED + PCA9685)

GPIO 34 → Battery Voltage (via 4:1 voltage divider)

I2C Devices

• 0x3C: SSD1306 OLED Display
• 0x40: PCA9685 PWM Driver (Servo Channel 0)

Power Supply

• Main Power: 7.4V LiPo → Motors, Servo
• Logic Power: ESP32 3.3V → LEDs, Logic circuits
• Voltage Divider: 7.4V → 1.85V (GPIO 34)

🏗️ Software Architecture

Core Systems

• Bluepad32 Framework: PS4 controller HID support
• FreeRTOS: Dual-core task management
• NVS Storage: Non-volatile odometry persistence
• I2C Communication: Multi-device bus management

Control Loops

• Main Loop: Controller input, lighting updates, display refresh
• Motor Control: PID-based speed regulation (50Hz)
• Encoder Reading: Interrupt-based quadrature decoding
• Battery Monitoring: 1Hz filtered voltage reading

Safety Features

• Watchdog Timer: System stability monitoring
• Connection Timeout: 2-second controller loss detection
• Motor Safety: Automatic stop on disconnection
• Servo Limiting: Mechanical binding prevention (50°-130°)

🛠️ Building and Uploading

Prerequisites

• PlatformIO (VS Code extension or CLI)
• Python 3.9+ with pip
• Git for version control

Setup Instructions

1. Clone Repository

   git clone <repository-url>
   cd esp32-rc-car

2. Install PlatformIO

   python3 -m pip install platformio

3. Build Firmware

   python3 -m platformio run

4. Upload to ESP32

   python3 -m platformio run --target upload

5. Monitor Serial Output

   python3 -m platformio device monitor

Build Configuration

• Platform: [email protected]
• Framework: Arduino with Bluepad32
• Board: ESP32 Dev Module
• Upload Speed: 921600 baud
• Monitor Speed: 115200 baud

Dependencies

lib_deps = 
    adafruit/Adafruit GFX Library@^1.11.9
    adafruit/Adafruit SSD1306@^2.5.10
    adafruit/Adafruit PWM Servo Driver Library@^3.0.2

🎮 Controls

PS4 Controller Mapping

Driving

• Left Stick X: Steering (±511 range)
• Right Trigger (R2): Throttle (0-1023)
• Left Trigger (L2): Brake (0-1023)

Lighting

• D-pad UP (tap): Toggle all lights ON/OFF
• D-pad UP (hold 1s): Flash headlights for 2 seconds
• Steering: Auto turn signals (±100 threshold)
• Brake Trigger: Auto brake lights (>50 threshold)

Navigation

• D-pad LEFT/RIGHT: Navigate trip computer pages
• D-pad DOWN (hold 3s): Reset current trip

Special Modes

• X Button: High-speed mode override
• Square: Direct PWM motor test mode
• L1 + R1: Motor diagnostics mode
• L1 + R1 + Circle: Battery diagnostics

Automatic Features

• Turn Signals: Activate when steering beyond ±100
• Brake Lights: Activate when brake > 50
• Auto-reconnection: Attempts reconnection every 5 seconds
• Safety Stop: Motors stop immediately on connection loss

📱 Display System

Startup Screen

[BT][LED]                    [BATT%]
     ┌─────────────────────┐
     │     Robot Logo      │
     │     (Bitmap)        │
     └─────────────────────┘
           ODO: 123.4m

Trip Computer Pages

[BT][LED]              [BATT%]

         Page Title
        
      ████████████
      █  123.4m  █
      ████████████
      
      Footer Text (if any)
      
      ●●○● (page dots)

Status Icons

• Bluetooth: Connected/Disconnected state
• LED Status:
  • 💡 Filled bulb: Lights ON
  • 💡 Hollow bulb: Lights OFF
  • ◄ Left arrow: Left turn signal
  • ► Right arrow: Right turn signal

🔧 Troubleshooting

Common Issues

Controller Won't Connect

• Ensure PS4 controller is in pairing mode (hold Share + PS buttons)
• Check Bluetooth range (<10 meters)
• Restart ESP32 and try pairing again
• Verify Bluepad32 framework is correctly installed

Motors Don't Move

• Check motor driver connections (PWM, INA, INB pins)
• Verify motor power supply (7.4V)
• Test with motor diagnostics mode (L1 + R1)
• Check encoder connections for feedback

LEDs Don't Light

• Verify GPIO pins are not input-only (avoid 34, 35, 36, 39)
• Check LED polarity (long leg to resistor)
• Test individual LEDs with multimeter
• Ensure 220Ω current-limiting resistors are used

Display Issues

• Verify I2C connections (SDA=21, SCL=22)
• Check OLED I2C address (0x3C)
• Test I2C bus with scanner code
• Ensure 3.3V power supply to OLED

Battery Monitoring

• Verify voltage divider (3× 10kΩ resistors)
• Check ADC pin connection (GPIO 34)
• Test with multimeter: expect 1.85V for 7.4V battery
• Calibrate voltage constants if needed

Debug Commands

• Battery Diagnostics: L1 + R1 + Circle
• Motor Tests: L1 + R1 (hold)
• Serial Monitor: 115200 baud for debug output
• Connection Status: Displayed on OLED

👨‍💻 Development

Code Structure

src/
├── main.cpp              # Main application code
├── trip_computer.cpp     # Odometry and navigation (integrated)
├── led_control.cpp       # Lighting system (integrated)
├── motor_control.cpp     # PID and motor drivers (integrated)
└── display.cpp           # OLED graphics (integrated)

platformio.ini            # Build configuration
CLAUDE.md                 # Development documentation
README.md                 # This file

Key Configuration Constants

// Motor Control
#define MAX_PWM 255
#define MIN_PWM 50
#define COUNTS_PER_REV 3638
#define WHEEL_CIRCUMFERENCE_M 0.2199f

// Battery Monitoring  
const float batteryMaxVoltage = 8.8f;
const float batteryMinVoltage = 6.4f;
const float voltageDividerRatio = 4.0f;

// Servo Control
#define SERVO_CENTER 90
#define SERVO_MAX_LEFT 130
#define SERVO_MAX_RIGHT 50

Adding New Features

1. Update pin definitions in main.cpp header
2. Add initialization code in setup()
3. Implement control logic in processGamepad()
4. Update display in displayTripComputer() or displayStartupScreen()
5. Test thoroughly with serial monitor output

Performance Monitoring

• RAM Usage: 27.1% (88,660 bytes)
• Flash Usage: 24.6% (774,165 bytes)
• Loop Frequency: ~50Hz (20ms cycle time)
• I2C Frequency: 400kHz (fast mode)

📄 License

This project is open source. Feel free to modify and distribute according to your needs.

🤝 Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test thoroughly
5. Submit a pull request

🙏 Acknowledgments

• Bluepad32 framework for PS4 controller support
• Adafruit libraries for hardware drivers
• PlatformIO for excellent ESP32 development environment
• ESP32 community for extensive documentation and examples

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🚗 Happy driving! Built with ❤️ and ESP32