RC-Car

ESP32 RC car system using ESP-NOW for low-latency wireless control. Three-board architecture: TX (joystick controller), RX (car with L298N motor driver), and CYD telemetry display. Features bidirectional heartbeat, FreeRTOS motor watchdog failsafe, long-range PHY mode, expo curves, EMA smoothing, and LEDC PWM with v2/v3 compatibility.

Overview

Board	Role	Description
TX	Transmitter	Hand-held joystick controller
RX	Receiver	Car-side motor driver interface
CYD	Telemetry	ESP32-2432S028R touchscreen display (in progress)

Features

• ESP-NOW wireless — sub-millisecond latency, no router required
• Long-range PHY — 802.11 LR mode for extended range and noise immunity
• Bidirectional heartbeat — TX and RX LEDs indicate link status in real time
• FreeRTOS motor watchdog — independent timer kills motors if main loop hangs
• Multi-layer failsafe — 200ms packet timeout + hardware watchdog + brownout protection
• Expo curves & EMA smoothing — configurable joystick response and jitter filtering
• LEDC PWM compatibility — shim layer supports Arduino-ESP32 v2.x and v3.x

Hardware

Components

• 3x ESP32 dev boards (any generic ESP32-WROOM-32 module)
• 1x L298N dual H-bridge motor driver
• 1x Dual-axis analog joystick module
• 1x ESP32-2432S028R (CYD) for telemetry (optional)
• 2x DC motors (steering + drive)

Wiring — RX (Car)

L298N Pin	ESP32 GPIO	Function
IN1	27	Steering direction 1
IN2	26	Steering direction 2
ENA	25	Steering PWM
IN3	33	Drive direction 1
IN4	32	Drive direction 2
ENB	14	Drive PWM

Wiring — TX (Controller)

Component	ESP32 GPIO	Function
Joystick Y	32	Throttle axis (ADC)
Joystick X	33	Steering axis (ADC)
UART TX	27	Telemetry data to CYD

Getting Started

Prerequisites

• PlatformIO (CLI or IDE plugin)
• USB cable for flashing each ESP32

Build & Flash

# Flash the transmitter
pio run -e tx -t upload

# Flash the receiver (car)
pio run -e rx -t upload

# Flash the telemetry display (optional)
pio run -e telemetry -t upload

Serial Monitor

pio device monitor -e tx     # TX debug output
pio device monitor -e rx     # RX debug output

Project Structure

RC_Car/
├── include/
│   ├── rc_protocol.h      # Shared packet definitions & ESP-NOW config
│   ├── tx_config.h        # TX pin assignments & joystick calibration
│   └── rx_config.h        # RX pin assignments & motor tuning
├── src/
│   ├── tx/main.cpp        # Transmitter firmware
│   ├── rx/main.cpp        # Receiver firmware
│   └── telemetry/         # CYD display firmware (in progress)
└── platformio.ini         # Build environments (tx, rx, telemetry)

Configuration

Key parameters are defined in the config headers — no code changes needed for basic tuning:

Parameter	File	Default	Description
ESPNOW_CHANNEL	rc_protocol.h	1	Wi-Fi channel (must match all boards)
FAILSAFE_MS	rc_protocol.h	200	Motor kill timeout on signal loss
JOY_THROTTLE_EXPO	tx_config.h	0.4	Throttle expo curve (0 = linear, 1 = cubic)
JOY_SMOOTHING	tx_config.h	0.3	EMA filter factor (0 = none, 1 = max)
STEER_FIXED_DUTY	rx_config.h	255	Steering motor power (0-255)
DEADZONE_THROTTLE	rx_config.h	80	Throttle deadzone (-1000..+1000 range)

License

This project is licensed under the MIT License — see the LICENSE file for details.