ESP32 Mini RC Car · Andrés Moreno

Project Overview

MCU

XIAO

Seeed ESP32-C3

Motor Driver

H-Bridge

TB6612FNG dual channel

Wireless

50

Hz ESP-NOW joystick packets

Build Status

Built

Assembled & bench-tested

At a Glance

TypePersonal project

My roleSolo: CAD, 3D printing, wiring, testing

CodeWritten with AI coding help

TimelineFeb – Mar 2026

SkillsMotor control · PWM · ESP-NOW · mechanical CAD

ToolsFusion 360 · Arduino C++ · Ender-3 S1 Pro → K1C · KiCad

StatusDriving · custom PCB in progress

A custom-designed, 3D-printed RC car — including the wheels — built around the Seeed Studio XIAO ESP32-C3. The chassis was modelled from scratch in Fusion 360 and printed in PLA: first on a Creality Ender-3 S1 Pro, then on a Creality K1C after bed-levelling and heated-bed problems on the Ender. Drive is handled by a DC 130 dual-shaft motor (3V–6V, 12,000 RPM, direct drive) controlled via a TB6612FNG H-bridge module, while steering uses an MG90 9 g metal-gear micro servo for Ackermann-style front-wheel control.

Wireless control runs over ESP-NOW between two ESP32-C3 boards — one on the car (receiver) and one on a breadboard transmitter: an ESP32-C3 SuperMini with two KY-023 analog joystick modules. Motor speed is controlled with LEDC PWM and joystick dead zones to keep low-speed movement stable.

The XIAO's built-in LiPo connector and onboard 3.3 V regulator eliminates the need for an external buck converter — the 3.7 V battery connects directly to the XIAO, motor module, and servo. A custom PCB to replace the protoboard wiring is in progress: the schematic is drawn in KiCad, and the board layout is the next step.

Bench test — XIAO, TB6612FNG, servo and motor validated before mounting

Three-quarter angle — front servo steering and 3D-printed wheel mounts

CAD Design & 3D Printing

The full chassis was designed parametrically in Fusion 360 as a multi-body assembly: main body, front steering knuckles, wheel mounts, motor bracket, servo bracket, and the wheels themselves — all 3D printed. Every component was designed to fit the micro servo and the DC 130 motor directly.

Phase 1 — Fusion 360 Design

Full chassis assembly with 4 wheels, motor mount, servo bracket, and electronics bay

The chassis was designed as a complete parametric assembly in Fusion 360. Components include: main chassis plate, front axle steering knuckles for Ackermann geometry, rear motor bracket sized to the DC 130 dual-shaft motor, servo bracket with horn clearance, four wheel mounts, and a top electronics bay for the PCB and LiPo cell. The wheels were also designed and printed, keeping the entire build self-made. All tolerances were set to account for FDM dimensional variation.

Phase 2 — 3D Printing (Ender-3 S1 Pro, then K1C)

PLA print with focus on front steering section and wheel cutout geometry

All chassis parts printed in PLA. I started on a Creality Ender-3 S1 Pro, but bed calibration and the heated bed kept causing problems, so I bought a Creality K1C and finished the parts on it. The front steering section with wheel cutouts required careful orientation to print without supports while maintaining dimensional accuracy for the servo horn interface. Layer height set to 0.2 mm for structural parts, 0.15 mm for steering knuckles requiring tighter tolerances. Parts were test-fitted before electronics installation.

CAD — Fusion 360

Design toolFusion 360 parametric

Chassis typeMulti-body assembly

Steering geometryAckermann front-wheel

Servo clearanceModelled for the MG90 micro servo

Motor mountDC 130 dual-shaft motor

3D Printing

PrinterEnder-3 S1 Pro → Creality K1C

MaterialPLA filament

Layer height (body)0.2 mm

Layer height (steering)0.15 mm

Support materialMinimised by orientation

Electronics & PCB Design

The electronics stack is built around the XIAO ESP32-C3 paired with a TB6612FNG H-bridge module. Supporting circuitry sits on a small protoboard: a power switch, red LED indicator, electrolytic capacitor for motor voltage spike suppression, and battery and motor connectors. A 100 nF ceramic capacitor is soldered across the motor terminals for brush noise suppression. A custom PCB replacing all of this is in progress in KiCad — the schematic was started in EasyEDA before being migrated to KiCad — targeting JLCPCB manufacture in the coming weeks.

TB6612FNG Pin	ESP32-C3 GPIO	Function
PWMB	D10	Motor speed control (PWM / LEDC)
BIN1	D4	Motor direction bit 1
BIN2	D5	Motor direction bit 2
STBY	3.3 V	Standby — pulled high to enable driver
VM	3.7 V LiPo	Motor power supply (direct from LiPo, no regulation)
VCC	3.3 V	Logic power — from XIAO's onboard 3.3 V regulator
Servo Signal	D7	PWM steering (MG90 metal-gear micro servo)

Firmware — Motor Control

FrameworkArduino / ESP32-C3 Core

PWM APILEDC (ESP32-Arduino v3+)

Joystick dead zone140 ADC counts (throttle)

Direction controlBIN1/BIN2 + PWMB

Steering controlMicro servo via D7

WirelessESP-NOW P2P · 50 Hz packets

PCB — KiCad Design

Design toolEasyEDA → KiCad

Board layers2-layer (planned)

MCU footprintXIAO ESP32-C3

Motor driverTB6612FNG breakout

ConnectorsServo header · power switch

Manufacture statusDesign in progress — JLCPCB

EasyEDA schematic — ESP32-C3, TB6612FNG, servo header, power switch and decoupling

PCB layout — in progress, targeting JLCPCB manufacture

Firmware

Written in Arduino C++ using the ESP-NOW API and the LEDC driver directly. The receiver auto-calibrates joystick centres on power-up (averages the first 60 readings) and requires the throttle to sit at centre briefly before arming — preventing a motor spin on connect. Motor PWM runs at 20 kHz on an 11-bit timer; servo outputs 50 Hz with pulse width constrained to 1000–2000 µs. A 400 ms failsafe cuts the motor if packets stop arriving.

Build & Assembly

Phase 1 — Bench Testing

Motor, servo, and driver validated independently before chassis mounting

Before final assembly, each subsystem was bench-tested independently. The TB6612FNG motor driver was tested for bidirectional PWM control with the XIAO ESP32-C3 using both LEDC channels. The micro servo was checked for full range of motion on GPIO D7. Motor direction switching and speed control were verified across the full PWM range. All bench tests ran from LiPo power through a bench PSU current limiter for safety.

Phase 2 — Chassis Assembly

3D-printed chassis assembled with motor, servo, and wheel mounts

All 3D-printed chassis parts assembled in sequence: rear motor bracket press-fitted and secured, front steering knuckles inserted with press-fit axle pins, micro servo mounted in its bracket with horn connected to the steering linkage, and all four wheels attached. Fit and full steering range were checked before installing any electronics.

Phase 3 — Electronics Mounting

XIAO ESP32-C3, TB6612FNG breakout, and LiPo mounted to chassis top plate

Electronics mounted to the chassis top plate. XIAO ESP32-C3 positioned for USB-C access, with its antenna sticker adhered to the chassis exterior for unobstructed RF. TB6612FNG module wired to all motor and GPIO pins per pin mapping table. LiPo cell positioned for centre-of-gravity balance. Wireless control tested end-to-end with the ESP-NOW transmitter — car drives and steers correctly in both directions.

Demo

Driving test — forward & reverse

Steering — left & right lock

Full drive — steering and throttle

Next Steps

PCB Design, Manufacture & Testing — JLCPCB

Complete the KiCad PCB design and submit to JLCPCB for 2-layer fabrication. Assemble the custom PCB and validate all subsystems: motor driver PWM, servo control, power supply, and ESP-NOW wireless link. Replace the current breakout-board wiring with the clean PCB-mounted solution.

Handheld Transmitter Controller Build

Design a dedicated handheld transmitter around a XIAO ESP32-C3 with the ESP-NOW TX firmware. The controller will feature a dual-axis analog joystick for throttle and steering, housed in a 3D-printed ergonomic enclosure designed in Fusion 360.

Body Shell — Fusion 360 & 3D Print

Design a full body shell enclosure in Fusion 360 that mounts over the electronics chassis — styled to look like a scaled car body. The shell clips onto the chassis top plate and includes ventilation slots for the motor and power electronics. Printed in PLA with optional colour accent pieces.

PWM & Dead Zone Tuning

Dial in the right PWM frequency and dead zone parameters for low-speed control precision and reliable direction switching. Current firmware uses hardcoded dead zones — a runtime tuning mode via the joystick will make it possible to dial these in on the fly and save them to EEPROM.