BNO085 9 Axis IMU Breakout Board

Product Description

Experiment with sensor fusion IMUs with the BNO085 Breakout Board.

• Sensor-Enabled: 9-axis accelerometer, gyro, and magnetometer provides precise motion tracking.
• Ready for Prototype: Common reports (e.g. Rotation Vectors) native to the BNO085 firmware coupled with STRDC’s library makes startup easy.
• Reliable: Dynamic calibration adjusts for changes over time and temperature.
• Application Ready: The BNO085 generates activity tracking reports for quick bring-up of step-counting and heart-rate monitoring.
• Power Conscious: Power management features like sleep and wake-on-motion maximize application requirements.
• Universal: Interface with I²C (QWIIC/Stemma Compatible), SPI, or UART. Includes a 5V to 3.3V level shifter and 5V to 3.3V power regulator.
• Lead-free

Features

• BNO085 9-Axis IMU (Accelerometer, Gyroscope, Magnetometer), separate I²C bus for environmental sensors
• Pre-installed sensor-fusion applications for Rotation Vectors, AR/VR Stabilization, Step-Counting, etc…
• Communicate over I²C, SPI, UART, or UART-RVC
• STRDC library for quick setup
• Compatible with 5V and 3.3V
• 3.3V power regulator
• Onboard LED to indicates power is applied
• Lead-Free

Pinout

Pin	I/O	Description
VDC	I	5V or 3.3V supply voltage matching communication logic level.
3V3	O	3.3V output from 5V to 3.3V power regulator (100mA max).
GND	-	Ground
SCL	I/O	I²C: SCL. SPI: SCK. UART: BNO085 TX. UART-RVC: NC.
SDA	I/O	I²C: SDA. SPI: MISO. UART: BNO085 RX. UART-RVC: BNO085 RX.
INT	I	Interrupt from BNO085 (active low).
CS	I	SPI: Chip Select.
DI	I/O	I²C: Lower bit of address. SPI: MOSI.
RST	I	BNO085 Reset (active low), connected to VDC with 10kΩ pullup.
P1	I	BNO085 PS1 pin for communication configuration. I²C: LOW. SPI: HIGH. UART: HIGH. UART-RVC: LOW.
P0	I	BNO085 PS0/Wake pin for communication configuration. I²C: LOW. SPI: HIGH. UART: LOW. UART-RVC: HIGH.
BT	I	BNO085 Bootloader Mode Select at power-up. Normal: HIGH. Bootloader: LOW.
ESCL	-	Environmental Sensor I²C SCL.
ESDA	-	Environmental Sensor I²C SDA.

Voltage Compatibility

The BNO085 Breakout Board can operate with both a 3.3V or a 5V supply on pin VDC. Logic levels should match supply voltage for proper operation.

Communication Interfaces

I²C

• I²C Address: The LSb of the address can be selected using the DI pin (LOW: 0x4A, HIGH: 0x4B), implement the intended configuration before power-on.
• Clock Speed: Up to 400 kHz
• Pull-up Resistors: Onboard 10kΩ pull-ups included
• Connector: 4-pin 1mm pitch JST QWIIC/Stemma Compatible connector

SPI

• Clock Speed: Up to 3 MHz
• SPI Mode: SPI Mode 3 (CPOL = 1, CPHA = 1)

UART

• Operating Baud Rate: 3Mbaud
• Data Format: 8 data bits, no parity, 1 stop bit
• Protocol: CEVA SHTP

UART-RVC

• Operating Frequency: 100 Hz

Interrupt Functionality

The BNO085 asserts the INT pin when it needs attention from the host (has data to send, needs to report an error, etc…). The pin will be asserted until the I²C address has been received on the bus or the SPI CS pin is asserted.

Note

The interrupt feature is only available in I²C and SPI modes.

Environmental Sensors

The BNO085 can communicate with external sensors on a separate I²C bus (broken out by ESCL and ESDA) and report them similar to its internal sensors. Review the BNO08x datasheet for more details and a complete list:

• Bosch Sensortec BME280 pressure/humidity/temperature sensor
• Bosch Sensortec BMP280 pressure/humidity/temperature sensor
• Capella Microsystems CM36686 proximity and ambient light sensor

Note

Both the BME280 and BMP280 cannot be connected simultaneously.

Software Library and Examples

To expedite prototyping, STRDC has created a BNO08x library included in our STRDC SDK. The library includes many examples that may be used to start prototyping or explore the full functionality of the BNO085. In addition to the library, the SDK also includes a HAL for the Teensy4.1 (Teensyduino) and common drivers for everything needed to communicate with the BNO085.

Examples on ArduinoIDE

To get started with the ArduinoIDE examples, ensure that the HAL, Drivers, and BNO08x Module are in the local Arduino libraries location. From there, compile and upload the example sketch.

Examples on PlatformIO

To get started with PlatformIO examples,

1. Create a new PlatformIO project selecting the target device and framework (Teensy4.1 and Arduino if using the HAL included in the SDK).

2. Update the platformio.ini file to include necessary dependencies (lib_deps)

3. Add additional necessary dependencies to the lib directory of the project (the HAL (if using Teensyduino) and Drivers in the SDK).

4. Add the desired example program main.cpp to the src directory of the project.

5. Compile and upload.

Connections

The device used to communicate with the breakout board will be referred to as “host”.

I²C

Connect the host to the breakout board as shown (VDC and GND connection are omitted).

Note

The BNO085 requires that the host support clock stretching.

Caution

P0 does not need to be connected to a host GPIO, but not doing so will prevent the host from waking or communicating with the BNO085 during sleep mode.
Connect P0 LOW if not connected to the host.

SPI

Connect the host to the breakout board as shown (VDC and GND connection are omitted).

Note

The BNO085 uses full-duplex communication for SPI. To prepare its buffers, the BNO085 needs the host to send a Wake signal when the host wants to communicate. P0 should be connected to the BNO_PIN_WAKE as selected in your program to ensure proper SPI communication.

Caution

P0 can be connected HIGH instead of a GPIO if desired, however this comes with some caveats:

1. The host will be unable to wake the BNO085 from sleep mode.
2. The host will only be able to send information to the BNO085 when the BNO085 prompts the host for a read (through the interrupt pin). E.g. If sensor reports are not enabled at startup, writes to the BNO085 may become impossible.
3. The STRDC BNO08x library was built for reliable SPI communication using the Wake signal. Modification may be required.

UART

Connect the host to the breakout board as shown (VDC and GND connection are omitted). RX and TX are the Host RX and TX.

Note

UART communication with the BNO085 uses control messages to establish when it is safe for host writes. The interrupt pin is used by the BNO085 to indicate it is about to send data. The interrupt pin may be left NC by the host if desired, however communication will only be possible through polling.

Caution

P0 does not need to be connected to a host GPIO, but not doing so will prevent the host from waking or communicating with the BNO085 during sleep mode.
Connect P0 LOW if not connected to the host.

UART-RVC

Connect the host to the breakout board as shown (VDC and GND connection are omitted). RX and TX are the Host RX and TX.

Note

The host does not transmit any data to the BNO085 in the UART-RVC configuration. The BNO085 transmits heading and sensor information at 100Hz on its TX pin. This is the only configuration available in this mode.

Use the specific UART_RVC example in the STRDC BNO08x library for this configuration.

Datasheets, Schematics, and More

STRDC BNO08x Library:

• STRDC SDK

Schematic:

• BNO085 Breakout Board Schematic

Chip Info and Product Datasheets:

• CEVA BNO085 Product Page
• CEVA BNO08X Datasheet
• CEVA SH-2 Reference Manual
• CEVA Sensor Hub Transport Protocol

Store Page:

• BNO085 9-axis IMU Breakout Board

FAQ

Q: Can I use multiple BNO085 IMUs on the same I²C bus?

A: Yes, the STRDC SDK includes an example for using multiple BNO085s (SPI and I²C). This example can be modified to be used with two BNO085s configured in I²C mode on the same bus, provided their addresses are configured differently.