Cerelog BCI/EEG Board User Guide

Welcome! This guide will walk you through setting up and using your Cerelog 8-channel Brain Computer Interface board.

Table of Contents

1. Safety & Legal Notices

⚠️ ELECTRICAL SHOCK HAZARD - READ IMMEDIATELY

This product does not have mains isolation circuitry. To prevent risk of serious injury or death from electrical shock, you MUST adhere to the following rules:

  • NEVER use this device on a human subject while it is connected to a desktop computer plugged into a wall outlet.
  • NEVER use this device on a human subject with a laptop computer that is actively charging from a wall outlet.
  • ALWAYS operate this device for human data collection using a laptop running on its own battery power, or by connecting the board to a LIPO battery for power.

Evaluation Board/Kit Important Notice

Cerelog, Inc. provides the enclosed product(s) under the following conditions: This evaluation board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES ONLY and is not considered by Cerelog, Inc. to be a finished end-product fit for general consumer use. Persons handling the product(s) must have electronics training and observe good engineering practice standards. As such, the goods being provided are not intended to be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including product safety and environmental measures typically found in end products that incorporate such semiconductor components or circuit boards. This evaluation board/kit does not fall within the scope of the European Union directives regarding electromagnetic compatibility, restricted substances (RoHS), recycling (WEEE), FCC, CE or UL, and therefore may not meet the technical requirements of these directives or other related directives.

2. Visual Demonstrations

Product Demo Video

[PLACEHOLDER FOR YOUTUBE PRODUCT DEMO]

Bias Probe Test

This video shows the bias probe in action, demonstrating its ability to reduce common-mode noise by simply touching a finger to the probe input.

[PLACEHOLDER FOR BIAS PROBE DEMO VIDEO]

3. What You'll Need

Required Third-Party Accessories:

IMPORTANT: Adapters & Default Setup

  • The board's default firmware is for **Sequential Montage**. To use all 8 channels, you must purchase **TWO (2) Adapters**.
  • To use the board with only **ONE (1) adapter**, you must switch to **Referential Montage** by modifying the firmware (See Section 8).
  • Power Source: For current USB-C data transfer, no battery is needed. A 3.7V LIPO battery is **required for portable use and for future Wi-Fi/Bluetooth features.**
  • Data Cable: A high-quality USB-C data cable.
  • Electrodes & Adapter(s): An EEG electrode cap and the appropriate adapter(s).
  • Electrode Gel/Paste: Conductive gel for good electrode contact.

4. Hardware Overview

[PLACEHOLDER FOR LABELED PCB DIAGRAM]

  • USB-C Port: For data, power, and charging.
  • JST-PH Battery Connector: For an optional 3.7V LIPO battery.
  • GPIO17 Status LED: This green LED provides crucial status information.
    • LED ON: The board is powered, registers are set, and it is actively transmitting data.
    • LED OFF: The board is not transmitting. This usually means the battery is low. The main power LED will turn off shortly after.

Connecting the Battery

Align the plug so the RED wire goes to 'RED' and BLACK goes to 'BLK'. To remove, do not pull the wires; squeeze the plastic connector and wiggle it out.

5. Software and Driver Setup

The board sends data to your computer over a virtual COM port via USB. Both visualization methods below require installing a driver first.

Step 1: Install Drivers

[User Action]: Please specify which USB-to-Serial driver is needed (e.g., CP210x or CH340) and provide a link. "Our board uses the CP210x driver. Download it from Silicon Labs."

After installation, connect the board. It should now appear as a COM port (e.g., `COM3` on Windows, `/dev/cu.usbserial-XXXX` on Mac/Linux).

Step 2: Choose Your Visualization Software

Method A: Python Web Plotter (Recommended)

This method uses a Python script to serve a real-time data plot to your web browser. Follow these steps carefully:

  1. Download Software & Configure COM Port:

    [PLACEHOLDER FOR GITHUB REPO LINK]

    Download or clone the software from the link above. Open the main Python file in an editor and change the COM port number to match the one your board is using.
  2. Install Dependencies: Make sure you have Python installed. Open a terminal or command prompt and run the following command to install the required libraries:
    pip install pyserial plotly
  3. Run the Script: In your terminal, navigate to the folder containing the script (`cd path/to/folder`) and run it:
    python your_script_name.py
  4. Windows PATH Troubleshooting: If you get an error that a command or module is not found, you may need to add Python's script directory to your system's PATH.
    • Search "Edit the system environment variables" in the Windows search bar and open it.
    • Click the "Environment Variables..." button.
    • Under "System variables", find and select the "Path" variable, then click "Edit...".
    • Click "New" and paste in the full path to your Python Scripts folder (e.g., `C:\Users\YourUser\AppData\Local\Programs\Python\Python39\Scripts`).
    • Click OK to save, then restart your terminal or code editor.
  5. View Data: Once the script is running, it will print a URL in the terminal (e.g., `http://127.0.0.1:8050/`). Click this link or copy-paste it into your web browser to see the live data plot.
  6. Performance Tuning: If the data plot is slow or laggy on your computer, open the Python script and find the browser refresh rate variable. Increase the time delay (e.g., from `100` to `500` milliseconds) and re-run the script.

Method B: Custom BrainFlow GUI (Advanced)

[PLACEHOLDER FOR CUSTOM BRAINFLOW GITHUB LINK AND USAGE INFO]

6. Running Your First EEG Session

  1. Hardware Assembly: Connect your EEG cap's cable to the required adapter(s). **Note:** Default Sequential Montage requires **two adapters**.
  2. Prepare Subject: Place cap, apply gel.
  3. Connect Reference/Bias: Attach REF and BIAS electrodes.
  4. Connect & Stream: Launch software, connect to COM port, start stream.
  5. Check Signal Quality: Fix noisy channels by adjusting position or adding gel.

7. Applications & Possibilities

This board is a versatile tool for developers and researchers. With custom software, you can explore a wide range of applications.

  • Signal Acquisition: Capture data for EEG, EMG (muscle), ECG (heart), and EOG (eye movement).
  • Neuroscience Paradigms: Design experiments based on P300, Event-Related Potentials (ERP), and SSVEP.
  • BCI & Control Systems: Develop systems to quantify emotional states or control robotics.

8. Advanced Usage: Firmware & Customization

Firmware Access is Restricted

To receive the firmware source code, email support@cerelog.com with your proof of purchase.

Modifying the firmware with the Arduino IDE (a non-affiliated tool) is necessary to:

  • Change Montage: Switch from sequential to referential mode to use a single 10-pin adapter.
  • Adjust Gain: Set the Programmable Gain to 1, 2, 4, 6, 8, 12, or 24.
  • Control Motor & LEDs: Implement your own code to use the haptic motor and debug LEDs.
  • Change Sample Rate/Resolution: This is a highly advanced change. Modifying these parameters will alter the data stream format and will likely require you to make significant changes to the Python/GUI software to parse the data correctly.

Procedure After Flashing Firmware

  1. After a successful flash, **unplug and plug back in the USB-C cable** to power cycle the board.
  2. Your computer may assign a new COM port number.
  3. You must edit your Python script again to select the correct new COM port.

⚠️ Motor Usage Advisory

Activating the motor will introduce noise into the EEG readings.

9. Troubleshooting

Problem: Board not detected (no COM port).
- Check driver installation. Use a known-good data cable. Try a new USB port.
Problem: Data is extremely noisy.
- The REF and BIAS connections are critical. Check them first. Re-apply gel.

10. Appendix: Pinout & Technical Details

Electrode Header Pinout

[PLACEHOLDER FOR ELECTRODE HEADER PINOUT DIAGRAM]

Technical Specifications

  • Input Channels: 8 differential, high gain, low noise input channels
  • ADC Resolution: 24-bit (see performance notes below)
  • Sample Rate: 500 SPS (default, firmware configurable)
  • Programmable Gain: 1, 2, 4, 6, 8, 12, 24 (firmware configurable)
  • Operating Voltage: 3.3V digital, +/-2.5V analog
  • Electrode Compatibility: Active and passive electrodes

Signal Characteristics & Performance Notes

The core of this board is the Texas Instruments ADS1299 chip. While the chip has exceptional performance, real-world board performance will differ.

  • Input Signal Range: The ADS1299 is designed for signals as low as ~10µV peak-to-peak.
  • Filtering: The board's input filtering is optimized for 1-50Hz. Signals up to 100Hz are usable but may show some attenuation.
  • System Noise: The overall system noise of the board will be higher than the theoretical minimum of the ADS1299 chip itself.
  • Datasheet: For complete details, see the official TI ADS1299 Datasheet. (Note: Third-party link).

Understanding Electrode Montages

  • Sequential / Bipolar Montage: (Default). Each channel measures the difference between a positive (INxP) and negative (INxN) input. Requires **two 10-pin adapters**.
  • Referential Montage: Each channel is measured relative to a common reference (REF). Requires firmware modification and a **single 10-pin adapter**.