PS5 Controlled Smart Car (ESP32)

An ESP32-based smart car controlled using a PS5 DualSense controller.

This project uses a non-blocking firmware architecture (no delay()), differential drive motor mixing, and a priority-based buzzer state machine.

Documentation: https://lukefrost112.github.io/RobotCar/

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Demo

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Features

• PS5 DualSense Bluetooth control (ESP32)
• Differential drive mixing (throttle + steering)
• Deadzone filtering for precise control
• Fully non-blocking firmware (no delay())
• Priority-based buzzer finite state machine:
  • Connect/disconnect beep patterns
  • Boost mode (fast aggressive buzz)
  • Reverse warning tone (slow buzz)
  • Horn mode
• RGB visual feedback system
• 10kHz PWM motor control (8-bit resolution)
• Hardware schematic documented with KiCad

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Firmware Architecture

The firmware follows a layered, non-blocking design.

Each loop iteration performs:

1. Read controller input
2. Decide buzzer state (priority logic)
3. Update buzzer system (single-writer to BUZ pin)
4. Update RGB feedback (non-blocking blink logic)
5. Compute drive command (throttle + steering mixing)
6. Map motor outputs to H-bridge pins
7. Write PWM values to motors

All timing is handled using millis().

No delay() is used anywhere in the system.

This ensures:

• Responsive controller input
• Stable Bluetooth connection
• Smooth motor control
• Deterministic feedback behavior

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Buzzer System

The buzzer is implemented as a priority-based finite state machine.

States

• PATTERN → Finite event-based beep patterns (connect/disconnect)
• BOOST → Fast square-wave buzz while boost is held
• HORN → Constant tone while horn button is pressed
• REVERSE → Slow square-wave warning tone while reversing
• STANDBY → Silence

Priority Order

PATTERN > BOOST > HORN > REVERSE > STANDBY

This guarantees that important system events (like disconnect) cannot be overridden by user input.

Design Principle

Only one function is allowed to write to the buzzer pin.

All buzzer behavior is selected through state logic and executed in a single update function.
This prevents multi-writer conflicts and timing glitches.

Timing Model

• Finite patterns use step counters and duration arrays.
• Continuous modes (BOOST / REVERSE) use square-wave toggling with millis() timing.
• State transitions reset timers to ensure predictable behavior.

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Motor Control

The car uses differential drive control.

Mixing Formula

left = throttle + steering
right = throttle - steering

This allows:

• Straight movement when steering = 0
• Turning while moving forward
• Pivot turns when throttle is near zero

Deadzone Filtering

Small joystick noise is removed using configurable deadzones for:

• Trigger inputs
• Left stick X axis

This prevents unwanted drift or micro-movements.

Output Mapping

Motor commands are clamped to ±255 and mapped to H-bridge direction pins.

PWM Configuration:

• Frequency: 10kHz
• Resolution: 8-bit (0–255 range)

This provides smooth motor response while remaining stable for the ESP32.

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Hardware Overview

The hardware is documented using a full KiCad schematic.

Core Components

• ESP32 Dev Board
• H-Bridge Motor Driver
• Active 5V Buzzer
• BC547 NPN Transistor (buzzer driver)
• RGB LED
• Voltage Regulator

Power Design

• ESP32 logic operates at 3.3V
• Buzzer operates at 5V via transistor driver
• Motor driver powered from main supply
• All modules share a common ground

Correct grounding is critical for:

• Stable Bluetooth connection
• Preventing random resets
• Clean motor operation

Buzzer Driver Wiring (Important)

The active buzzer is powered using a BC547 transistor:

• GPIO → 1kΩ resistor → Base
• Base → GND via 10kΩ (optional but recommended)
• Emitter → GND
• Collector → Buzzer negative
• Buzzer positive → +5V

This ensures:

• Proper volume
• Safe GPIO current
• Reliable operation

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Build Instructions

1. Flash the firmware to the ESP32.

2. Set your controller MAC address in the code:

   'ps5.begin("XX:XX:XX:XX:XX:XX");'

3. Verify all modules share a common ground.

4. Confirm motor driver wiring matches the schematic.

5. Power the system and pair the PS5 controller.

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Documentation Site

Full project documentation: https://lukefrost112.github.io/RobotCar/

Includes:

• System architecture
• Buzzer subsystem explanation
• Motor control breakdown
• RGB feedback logic
• Hardware schematic

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License

MIT License