EEG Hardware Setup Guide

This guide provides step-by-step instructions for assembling the EEG signal acquisition system. The setup includes an Arduino Uno, an AD620 instrumentation amplifier, EEG electrodes, and the necessary wiring for signal processing and transmission.

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Hardware Components

1. Microcontroller

• Arduino Uno – Used to process EEG signals and communicate with a computer.

2. EEG Electrodes

• Dry or wet electrodes (minimum of three: signal, reference, and ground).
• Alligator clips for secure electrode connections.

3. Amplifier Circuit

• AD620 Instrumentation Amplifier – Used for signal amplification.

4. Resistor

A single resistor placed on the breadboard for signal stabilization.

5. Wiring Components

• Jumper wires – For connecting the amplifier, electrodes, and Arduino.
• Breadboard – Used for assembling the AD620 circuit.

6. Power Supply

• 5V from Arduino Uno – Powers the amplifier and EEG circuit.

  

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Wiring Diagram & Connections

AD620 Placement on Breadboard

• Placed on E6, E7, E8, E9 (left side) and F6, F7, F8, F9 (right side).

Resistor Placement

• D6 to G6 on the breadboard.

###Connections to Arduino Uno

Breadboard Pin	Arduino Uno Pin
D7	5V (Analog)
D8	A0 (Analog Input)
D9	Negative Bus strip
GND(Arduino)	Negative Bus strip

Electrode Connections

Breadboard Pin	Electrode Connection
G7	Signal Electrode (Alligator Clip)
G8	Signal Electrode (Alligator Clip)
G9	Negative Bus strip

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Arduino Code

Upload the following code to the Arduino Uno to read and transmit EEG signals:

const int SIGNAL_PIN = A0;  // Pin connected to the EEG signal
const int SAMPLING_RATE = 100;  // Sampling rate in Hz (matches Python code)
const int SAMPLING_INTERVAL = 1000 / SAMPLING_RATE;  // Interval in milliseconds

void setup() {
  Serial.begin(9600);  // Start serial communication at 9600 baud rate
}

void loop() {
  // Read the raw EEG signal
  int rawValue = analogRead(SIGNAL_PIN);

  // Convert the raw value to voltage (assuming 5V reference and 10-bit ADC)
  float voltage = rawValue * (5.0 / 1023.0);

  // Send the voltage value to the Python script
  Serial.print("Voltage: ");
  Serial.println(voltage, 4);  // Send voltage with 4 decimal places

  // Wait for the next sample
  delay(SAMPLING_INTERVAL);
}

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Setup Instructions

1. Connect the Electrodes

• Attach the signal electrode to the scalp (e.g., forehead).
• Attach the reference electrode to a neutral location (e.g., earlobe).
• Attach the ground electrode to a location with minimal electrical activity (e.g., another earlobe).

2. Power Up the System

• Connect the Arduino Uno to your computer via USB.
• Ensure the AD620 amplifier receives power from the Arduino (5V).

3. Upload the Code

• Open the Arduino IDE.
• Copy and paste the provided code into a new sketch.
• Select the correct board (Arduino Uno) and port.
• Upload the code.

4. Test the Setup

• Open the Serial Monitor in the Arduino IDE (set baud rate to 9600).

• Observe the EEG signal values being printed.

• Ensure the values change when focusing or relaxing.

  

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Troubleshooting

No Signal Detected

• Check all electrode connections and ensure they are properly attached to the skin.
• Verify that the AD620 amplifier is powered and correctly wired.

Noisy or Unstable Signal

• Ensure the ground electrode is properly attached.
• Keep wiring away from power cables or other sources of electrical interference.

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References

AD620 Datasheet Arduino Documentation ESP32 Documentation