In this update, we will show you how to build a DIY robotic toy car that you can drive using your brainwaves and muscle signals!

NeuroCarX is an open-source project that combines EEG and EMG biopotential signals to create an intuitive brain-computer interface for robotic control.

Overview

This project uses two types of bio-potential signals to control a robotic car wirelessly:

• EEG (Electroencephalography) When you focus, the car moves forward.
• EMG (Electromyography) Flex your left/right arms to steer left and right or flex both arms to reverse.

All this is powered by NPG Lite, an open-source BioPotential signal acquisition device with:

• Built-in 3-channel BioAmp
• Bluetooth Low Energy (BLE) support
• Completely wireless control

How It Works

The system interprets your biopotential signals and translates them into car movements:

What You’ll Need

Hardware Components

• NPG Lite (Neuro PlayGround Lite)
• Robotic car chassis
• Seeed Studio XIAO ESP32C6 board
• MX1508/MX1616 motor driver
• LiPo battery
• 7 pcs. BioAmp Snap/Alligator Cables
• 7 pcs. gel electrodes
• Nuprep skin preparation gel (optional)
• Alcohol swabs
• Slide switch

Tools Required

• Soldering iron
• Solder
• Laptop
• Connecting wires
• Wire cutters
• Wire strippers
• Screwdriver
• USB-C cable(s)

Software Requirements

• Arduino IDE
• BLE-BCI-Car-Remote firmware(for NPG Lite)
• BLE-BCI-Car firmware(for XIAO ESP32C6)

About the Components

NPG Lite

A compact, wireless amplifier for recording EMG, ECG, EOG, and EEG signals.

• Adafruit Feather form factor
• Wi-fi, Bluetooth, Zigbee, and Thread connectivity
• User safety and ESD protection
• LEDs, buttons, LiPo charging, USB-C
• Ideal for research, education, and BCI projects

XIAO ESP32C6

Acts as the receiver on the robotic car, listening for wireless commands from NPG Lite and controlling the motors accordingly.

Assembly Guide

Step 1: Build the Robotic Base

1. Watch this video for step-by-step guidance, you only need motor and wheel assembled to the chassis:

3. After the basic car build, follow the circuit diagram below for wiring and connections.
4. Once you have assembled the robotic car chassis and mounted the motors to the chassis.
5. Connect motors to the MX1508/MX1616 motor driver
6. Mount the XIAO ESP32C6 board on the chassis
7. Connect the LiPo battery
8. Wire everything according to the circuit diagram

Skin Preparation

For optimal signal quality:

1. Apply Nuprep Gel to each electrode placement site
2. Gently rub to remove dead skin cells and oils
3. Clean with alcohol swabs

This preparation significantly improves signal acquisition quality.

Electrode Placement Guide

Placement Tips

• EEG: Place A0P on forehead for optimal focus detection
• EMG: Position on forearms where muscle contractions are felt
• Reference: Place REF behind left ear for stability
• Press firmly for good gel contact
• Stay still during calibration

Step 2: Arduino IDE Configuration

Install ESP32 Package

1. Go to Tools → Board → Board Manager
2. Search for: esp32 by Espressif Systems
3. Select version 3.2.0 (important)
4. Click Install

Note: Do not install the Arduino ESP32 boards package from Arduino.

Install Required Library

1. Go to Sketch → Include Library → Manage Libraries
2. Search for: Adafruit NeoPixel by Adafruit
3. Click Install

Select Board for NPG Lite

• Go to Tools → Board → esp32
• Select: ESP32C6 Dev Module

Enable CDC on Boot

• Go to Tools
• Set CDC On Boot → Enabled

Firmware Setup

Step 1: Flash NPG Lite

1. Connect NPG Lite via USB-C
2. Open Arduino IDE
3. Select ESP32C6 Dev Module board
4. Flash the BLE-BCI-Car-Remote firmware
5. Open Serial Monitor (disconnect charger and avoid AC appliances)
6. Observe beta-wave % while focusing
7. Note your relaxed state %
8. Set threshold slightly above relaxed (default: 2%)
9. Reflash firmware with new threshold
10. Disconnect USB-C (runs wirelessly from here)

Step 2: Flash Car Receiver

1. Connect XIAO ESP32C6 via USB-C
2. Select XIAO ESP32C6 board
3. Flash the BLE-BCI-Car firmware
4. Disconnect USB

Control Commands

Operation Guide

Getting Started

1. Power on NPG Lite (ensure electrodes placed)
2. Power on the robotic car
3. Wait for Bluetooth connection

Controls

• Focus/Concentrate → Forward
• Flex left arm → Turn Left
• Flex right arm → Turn Right
• Flex right and left arm together → Reverse
• Relax → Stop/Idle

Performance Tips

• Stay 5m away from AC appliances
• Maintain good electrode contact
• Practice focusing for better control
• Use deliberate muscle contractions

Troubleshooting

Poor Signal Quality

• Clean & reapply electrodes
• Check all connections
• Minimize movement
• Ensure skin prep
• Move away from interference

Connection Issues

• Verify Bluetooth enabled
• Check batteries
• Ensure correct firmware
• Reset and reconnect
• Stay within 10m range

Car Not Responding

• Check motor wiring & battery
• Verify XIAO ESP32C6 receiving commands
• Test motors individually
• Adjust threshold calibration

Calibration Problems

• Disconnect laptop charger
• Avoid AC appliances
• Practice consistent focus states
• Adjust threshold as needed

Technical Details

Signal Processing

• EEG Focus Detection → Beta-wave thresholding
• EMG Detection → Amplitude-based contractions
• Wireless → BLE communication
• Response → Sub-second latency

Hardware Specs

• NPG Lite → 3-channel BioAmp, wireless
• XIAO ESP32C6 → Dual-core, BLE
• Motor Control → PWM speed + direction
• Power → Rechargeable LiPo

Applications & Use Cases

• Neurotechnology Research (BCI interface development)
• Accessibility Technology (assistive devices)
• STEM Education (learning + demos)
• Human-Computer Interaction (novel interfaces)
• Rehabilitation (motor skill training)

Future Enhancements

• Speed modulation (signal strength)
• Obstacle avoidance (sensors)
• Multi-user collaboration
• Machine learning adaptive recognition

Learn More

Resources

• GitHub Repository (code + docs)
• Get NPG Lite on Crowd Supply

Documentation

• Official Docs
• Signal Troubleshooting Guide

Community

• Discord
• GitHub

Support

Need help?

• Contact Us
• Report bugs on GitHub
• Contribute PRs