How to Use Adafruit EYESPI BFF: Examples, Pinouts, and Specs

The Adafruit EYESPI BFF (Manufacturer Part ID: 5772) is a compact breakout board designed to simplify the integration of eye-tracking sensors with microcontrollers. It leverages the SPI (Serial Peripheral Interface) protocol for fast and efficient communication, making it ideal for projects that require precise and responsive eye-tracking capabilities. This board is part of Adafruit's "BFF" (Best Friend Forever) series, designed to complement microcontroller boards like the QT Py and Feather.

• Eye-tracking systems for assistive technologies
• Gaming and virtual reality (VR) applications
• Human-computer interaction (HCI) projects
• Robotics and automation requiring gaze detection
• Research and development in cognitive science and psychology

The Adafruit EYESPI BFF is designed to provide a seamless connection between eye-tracking sensors and microcontrollers. Below are its key technical details:

The EYESPI BFF features an 18-pin FPC connector for interfacing with eye-tracking sensors. Below is the pinout description:

The Adafruit EYESPI BFF is designed for easy integration with microcontrollers. Follow the steps below to use it in your project:

1. Soldering: Solder the EYESPI BFF to your Adafruit QT Py or Feather board. Ensure proper alignment of the pins.
2. Sensor Connection: Attach the eye-tracking sensor to the 18-pin FPC connector on the EYESPI BFF using a compatible flat ribbon cable.
3. Power Supply: Ensure your microcontroller is powered with 3.3V, as the EYESPI BFF operates at this voltage level.
4. SPI Configuration: Connect the SPI pins (SCK, MISO, MOSI, CS) to the corresponding pins on your microcontroller.

Below is an example of how to configure and communicate with the EYESPI BFF using an Arduino-compatible board:

#include <SPI.h>

// Define SPI pins
#define CS_PIN 10  // Chip Select pin
#define INT_PIN 2  // Interrupt pin

void setup() {
  // Initialize Serial Monitor
  Serial.begin(9600);
  while (!Serial);

  // Configure SPI settings
  SPI.begin();
  pinMode(CS_PIN, OUTPUT);
  pinMode(INT_PIN, INPUT);

  // Set Chip Select pin to HIGH (inactive)
  digitalWrite(CS_PIN, HIGH);

  Serial.println("EYESPI BFF Initialized");
}

void loop() {
  // Example: Send a command to the sensor
  digitalWrite(CS_PIN, LOW); // Activate Chip Select
  SPI.transfer(0x01);        // Send a dummy command
  digitalWrite(CS_PIN, HIGH); // Deactivate Chip Select

  // Check for interrupt signal
  if (digitalRead(INT_PIN) == HIGH) {
    Serial.println("Sensor interrupt detected!");
  }

  delay(1000); // Wait for 1 second
}

• Voltage Compatibility: Ensure your microcontroller operates at 3.3V logic levels to avoid damaging the EYESPI BFF.
• Cable Handling: Use a high-quality flat ribbon cable to connect the sensor to the FPC connector for reliable communication.
• Interrupt Handling: If your sensor uses the INT pin, configure your microcontroller to handle interrupts efficiently.
• Firmware Updates: Check Adafruit's website for any firmware updates or additional libraries for your specific sensor.

1. No Communication with Sensor

   • Cause: Incorrect SPI wiring or configuration.
   • Solution: Double-check the SPI connections (SCK, MISO, MOSI, CS) and ensure the SPI settings in your code match the sensor's requirements.

2. Sensor Not Detected

   • Cause: Loose or improper connection to the FPC connector.
   • Solution: Ensure the flat ribbon cable is securely connected to the FPC connector.

3. Interrupts Not Triggering

   • Cause: INT pin not configured correctly in the code.
   • Solution: Verify the INT pin is set as an input and check the sensor's datasheet for interrupt behavior.

4. Overheating

   • Cause: Incorrect voltage supply.
   • Solution: Ensure the EYESPI BFF is powered with 3.3V only.

Q: Can I use the EYESPI BFF with 5V microcontrollers?
A: No, the EYESPI BFF is designed for 3.3V logic levels. Using it with 5V microcontrollers may damage the board.

Q: What sensors are compatible with the EYESPI BFF?
A: The EYESPI BFF is compatible with a variety of eye-tracking sensors that use SPI communication. Refer to Adafruit's product page for a list of supported sensors.

Q: Can I use multiple EYESPI BFF boards in a single project?
A: Yes, but you must assign unique Chip Select (CS) pins for each board to avoid communication conflicts.

Q: Where can I find additional resources?
A: Visit the Adafruit EYESPI BFF product page for detailed documentation, tutorials, and support.

By following this documentation, you can effectively integrate the Adafruit EYESPI BFF into your projects and unlock the potential of eye-tracking technology!