How to Use BNO055: Examples, Pinouts, and Specs

The BNO055 is a 9-axis absolute orientation sensor that integrates a 3-axis accelerometer, a 3-axis gyroscope, and a 3-axis magnetometer into a single package. Unlike traditional sensors, the BNO055 features an onboard microcontroller that fuses raw sensor data to provide accurate orientation information in the form of Euler angles (pitch, roll, yaw) or quaternions. This eliminates the need for complex sensor fusion algorithms on the host microcontroller.

• Robotics for precise motion tracking and navigation
• Drones for stable flight control and orientation sensing
• Virtual reality (VR) and augmented reality (AR) systems
• Wearable devices for activity tracking
• Industrial automation and human-machine interfaces

1. Power Supply: Connect the VIN pin to a 3.3V or 5V power source and the GND pin to ground.
2. Communication Interface:
   • For I²C, connect the SDA and SCL pins to the corresponding pins on your microcontroller. Pull-up resistors (typically 4.7kΩ) are required on these lines.
   • For UART, connect the TX and RX pins to the UART pins on your microcontroller.
   • For SPI, configure the PS0 and PS1 pins accordingly and connect the SPI lines (MISO, MOSI, SCK, CS).
3. Protocol Selection: Use the PS0 and PS1 pins to select the desired communication protocol:
   • I²C: PS0 = 0, PS1 = 1
   • UART: PS0 = 1, PS1 = 0
   • SPI: PS0 = 1, PS1 = 1
4. Reset: Optionally, connect the RST pin to a GPIO pin on your microcontroller for manual reset functionality.

• Ensure proper decoupling capacitors are placed near the VIN pin to stabilize the power supply.
• The BNO055 requires a stable clock signal for accurate measurements. Avoid noisy power sources.
• Use level shifters if interfacing with a 5V microcontroller to prevent damage to the sensor.

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BNO055.h>

// Create an instance of the BNO055 sensor
Adafruit_BNO055 bno = Adafruit_BNO055(55);

void setup() {
  Serial.begin(9600); // Initialize serial communication
  while (!Serial) {
    delay(10); // Wait for the serial port to be ready
  }

  // Initialize the BNO055 sensor
  if (!bno.begin()) {
    Serial.println("BNO055 not detected. Check connections.");
    while (1); // Halt execution if the sensor is not found
  }

  bno.setExtCrystalUse(true); // Use external crystal for better accuracy
  Serial.println("BNO055 initialized successfully.");
}

void loop() {
  // Get orientation data (Euler angles)
  sensors_event_t event;
  bno.getEvent(&event);

  // Print pitch, roll, and yaw to the serial monitor
  Serial.print("Pitch: ");
  Serial.print(event.orientation.x);
  Serial.print(" Roll: ");
  Serial.print(event.orientation.y);
  Serial.print(" Yaw: ");
  Serial.println(event.orientation.z);

  delay(100); // Delay to avoid flooding the serial monitor
}

1. Sensor Not Detected:

   • Ensure the correct I²C address (default: 0x28) is being used.
   • Check the wiring and ensure pull-up resistors are present on the SDA and SCL lines.
   • Verify that the PS0 and PS1 pins are configured for I²C mode.

2. Incorrect Orientation Data:

   • Ensure the sensor is mounted correctly and aligned with the desired axes.
   • Calibrate the sensor using the built-in calibration routines.

3. No Data Output:

   • Verify that the communication interface (I²C, UART, or SPI) is correctly configured.
   • Check the power supply voltage and ensure it is within the specified range.

• Use a logic analyzer or oscilloscope to verify communication signals.
• Test the sensor with a known working library, such as the Adafruit BNO055 library.
• If using I²C, scan for devices on the bus to confirm the sensor's address.

By following this documentation, you should be able to successfully integrate and use the BNO055 sensor in your projects.