How to Use GY 91: Examples, Pinouts, and Specs

The GY-91 is a compact and versatile sensor module that integrates multiple sensors into a single board. It features a 3-axis accelerometer, a 3-axis gyroscope, and a 3-axis magnetometer, making it ideal for applications requiring motion tracking, orientation sensing, and environmental awareness. The module is based on the MPU-9250 (IMU) and BMP280 (barometric pressure sensor) chips, providing high precision and reliability.

• Robotics and autonomous vehicles
• Drones and UAVs for stabilization and navigation
• Mobile devices for motion detection and orientation
• Wearable devices for fitness tracking
• Gaming controllers and virtual reality systems

1. Power Supply: Connect the VCC pin to a 3.3V or 5V power source and the GND pin to ground.
2. Communication Interface:
   • For I2C: Connect the SCL and SDA pins to the corresponding I2C pins on your microcontroller.
   • For SPI: Connect the CS, SDO, and SCL pins to the SPI interface of your microcontroller.
3. Pull-Up Resistors: If using I2C, ensure pull-up resistors (typically 4.7kΩ) are connected to the SCL and SDA lines.
4. Interrupt Pin: Optionally, connect the INT pin to a GPIO pin on your microcontroller to handle interrupts.

• Ensure the operating voltage matches the microcontroller's logic level (3.3V or 5V).
• Use proper decoupling capacitors near the power supply pins to reduce noise.
• Avoid placing the module near strong magnetic fields or vibrations to maintain accuracy.

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_MPU6050.h>
#include <Adafruit_BMP280.h>

// Create instances for MPU6050 (IMU) and BMP280 (barometric sensor)
Adafruit_MPU6050 mpu;
Adafruit_BMP280 bmp;

void setup() {
  Serial.begin(115200);
  while (!Serial); // Wait for Serial Monitor to open

  // Initialize MPU6050
  if (!mpu.begin()) {
    Serial.println("Failed to find MPU6050 chip!");
    while (1);
  }
  Serial.println("MPU6050 initialized successfully!");

  // Initialize BMP280
  if (!bmp.begin(0x76)) { // Default I2C address for BMP280
    Serial.println("Failed to find BMP280 sensor!");
    while (1);
  }
  Serial.println("BMP280 initialized successfully!");
}

void loop() {
  // Read accelerometer and gyroscope data
  sensors_event_t a, g, temp;
  mpu.getEvent(&a, &g, &temp);

  // Print accelerometer data
  Serial.print("Accel X: "); Serial.print(a.acceleration.x); Serial.print(" m/s^2, ");
  Serial.print("Y: "); Serial.print(a.acceleration.y); Serial.print(" m/s^2, ");
  Serial.print("Z: "); Serial.print(a.acceleration.z); Serial.println(" m/s^2");

  // Print gyroscope data
  Serial.print("Gyro X: "); Serial.print(g.gyro.x); Serial.print(" rad/s, ");
  Serial.print("Y: "); Serial.print(g.gyro.y); Serial.print(" rad/s, ");
  Serial.print("Z: "); Serial.print(g.gyro.z); Serial.println(" rad/s");

  // Read and print barometric pressure
  Serial.print("Pressure: "); Serial.print(bmp.readPressure()); Serial.println(" Pa");

  // Delay for readability
  delay(1000);
}

1. No Data from the Sensor:

   • Ensure the wiring is correct and matches the selected communication protocol (I2C or SPI).
   • Verify that the I2C address (default: 0x68 for MPU9250, 0x76 for BMP280) is correct in your code.
   • Check for loose connections or damaged wires.

2. Inaccurate Readings:

   • Calibrate the accelerometer, gyroscope, and magnetometer before use.
   • Avoid placing the module near sources of electromagnetic interference.

3. Module Not Detected:

   • Ensure pull-up resistors are present on the I2C lines.
   • Confirm that the power supply voltage is within the specified range.

• Use an I2C scanner sketch to detect the module's address.
• Test the module with a different microcontroller to rule out hardware issues.
• Check the datasheets for MPU-9250 and BMP280 for advanced configuration options.

By following this documentation, you can effectively integrate the GY-91 sensor module into your projects and troubleshoot common issues with ease.