How to Use BNO055: Examples, Pinouts, and Specs

The BNO055 is a 9-axis absolute orientation sensor developed by Bosch and distributed by Adafruit. It integrates a 3-axis accelerometer, a 3-axis gyroscope, and a 3-axis magnetometer, along with an onboard microcontroller that fuses the sensor data to provide accurate orientation information. Unlike traditional sensors, the BNO055 eliminates the need for complex sensor fusion algorithms, making it an ideal choice for applications requiring precise motion tracking and orientation.

• Robotics for navigation and control
• Drones for stabilization and orientation
• Virtual reality (VR) and augmented reality (AR) systems
• Wearable devices for motion tracking
• Industrial automation and control systems

The BNO055 is a highly versatile sensor with the following key specifications:

The BNO055 breakout board from Adafruit has the following pin layout:

The BNO055 can be easily interfaced with an Arduino UNO using the I²C protocol. Follow these steps to connect the sensor:

1. Wiring:

   • Connect the VIN pin of the BNO055 to the 5V pin on the Arduino.
   • Connect the GND pin of the BNO055 to the GND pin on the Arduino.
   • Connect the SDA pin of the BNO055 to the A4 pin on the Arduino.
   • Connect the SCL pin of the BNO055 to the A5 pin on the Arduino.

2. Install the Adafruit BNO055 Library:

   • Open the Arduino IDE.
   • Go to Sketch > Include Library > Manage Libraries.
   • Search for "Adafruit BNO055" and install the library.

3. Example Code: Use the following example code to read orientation data from the BNO055:

   #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 the BNO055 sensor
     if (!bno.begin()) {
       Serial.println("Error: BNO055 not detected. Check wiring or I2C address.");
       while (1);
     }
     Serial.println("BNO055 initialized successfully!");
     bno.setExtCrystalUse(true); // Use external crystal for better accuracy
   }
   
   void loop() {
     // Get the Euler angles (heading, roll, pitch)
     sensors_event_t event;
     bno.getEvent(&event);
   
     // Print orientation data to the Serial Monitor
     Serial.print("Heading: ");
     Serial.print(event.orientation.x);
     Serial.print("°, Roll: ");
     Serial.print(event.orientation.y);
     Serial.print("°, Pitch: ");
     Serial.print(event.orientation.z);
     Serial.println("°");
   
     delay(500); // Delay for readability
   }
   

• Power Supply: Ensure the sensor is powered within its operating voltage range (3.3V to 5V).
• I²C Pull-Up Resistors: The BNO055 breakout board includes onboard pull-up resistors for the I²C lines. Avoid adding external pull-ups unless necessary.
• External Crystal: For improved accuracy, the BNO055 can use an external crystal oscillator. This is enabled by default on the Adafruit breakout board.
• Mounting Orientation: The sensor's orientation affects its readings. Ensure it is mounted securely and aligned with your system's coordinate axes.

1. Sensor Not Detected:

   • Cause: Incorrect wiring or I²C address mismatch.
   • Solution: Double-check the connections and ensure the I²C address is set to 0x28 (default).

2. Inaccurate Readings:

   • Cause: Magnetic interference or improper calibration.
   • Solution: Perform a full calibration using the Adafruit library's calibration example.

3. No Output on Serial Monitor:

   • Cause: Incorrect baud rate or missing Serial.begin() in the code.
   • Solution: Ensure the baud rate in the code matches the Serial Monitor's setting.

1. Can the BNO055 be used with a 3.3V microcontroller?

   • Yes, the BNO055 operates at 3.3V and is compatible with 3.3V logic levels.

2. How do I switch between I²C and UART modes?

   • Use the PS0 and PS1 pins to configure the communication protocol:
     • I²C mode: PS0 = 0, PS1 = 0 (default)
     • UART mode: PS0 = 1, PS1 = 0

3. What is the maximum cable length for I²C communication?

   • The maximum length depends on the pull-up resistor values and the I²C clock speed. For reliable communication, keep the cable length under 1 meter.

By following this documentation, you can effectively integrate the BNO055 into your projects and leverage its powerful orientation sensing capabilities.