BNO055 STM32 library

This project demonstrates how to use the STM32 NUCLEO-H7A3ZI-Q to read data from a BNO055 IMU sensor via I2C and transmit the data to a PC over UART. The code is based on the bno055_stm32 repository.

This repository now serves as documentation of how I configured the IMU sensor with the microcontroller. I hope it can help others who are starting with IMU sensors and STM32 development.

Hardware and Software Configuration

Step 1: Open the .ioc File in STM32CubeIDE

• Launch STM32CubeIDE and open the .ioc file for the project.

Step 2: Enable and Configure I2C1

1. Navigate to Pinout & Configuration.
2. Under the peripherals list (A → Z), search for I2C1.
3. Enable I2C1 and configure it in GPIO Settings as shown in the image below.

Note:

The default pins for I2C1 were PB6 (I2C1_SCL) and PB7 (I2C1_SDA), but these pins did not work in my setup.
So I changed the pins to:

• PB8 (I2C1_SCL)
• PB9 (I2C1_SDA)

Step 3: Adjust Code Generation Settings

1. Go to Project Manager → Code Generator.
2. Uncheck the box for Generate peripheral initialization as a pair of .c/.h files per peripheral.

Step 4: Save the Configuration

• Press Ctrl + S to save the .ioc file, which will regenerate the code with the updated configuration.

Step 5: Add Flags for Float Support in printf and scanf

To enable floating-point support in printf and scanf, follow these steps:

1. Go to Project → Properties in STM32CubeIDE.
2. Navigate to C/C++ Build → Settings.
3. Under the Tool Settings tab, find Miscellaneous (under MCU GCC Linker).
4. In the Other Flags field, add the following flags:
   • -u _printf_float
   • -u _scanf_float
5. Click Apply and Close to save the changes.

This step ensures that floating-point values can be properly handled in formatted input/output functions like printf and scanf.

Step 6: Add the Required Files to Your Project

Add these files to your project:

• Place bno055.c in the Core/Src folder.
• Place bno055.h and bno055_stm32.h in the Core/Inc folder.

Step 7: Import the Library in main.c

1. Open main.c in STM32CubeIDE.
2. Add the following includes inside the /* USER CODE BEGIN Includes */ section:

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <stdio.h>
#include "string.h"
#include "bno055_stm32.h"
/* USER CODE END Includes */

Step 8: Add IMU Setup Code

• In the /_ USER CODE BEGIN 2 _/ section of main.c, add the following setup code to initialize the BNO055 IMU sensor:

/* USER CODE BEGIN 2 */
bno055_assignI2C(&hi2c1);
bno055_setup();
bno055_setOperationModeNDOF();
/* USER CODE END 2 */

Step 9: Write a Function to Fetch and Transmit IMU Data

1. Inside the /_ USER CODE BEGIN 0 _/ section of main.c, add the following function:

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
void send_imu_data() {
    char buffer[100];

    // Get Orientation and Linear Acceleration data
    bno055_vector_t orient = bno055_getVectorEuler();
    bno055_vector_t linear = bno055_getVectorLinearAccel();

    // IMU data
    snprintf(buffer, sizeof(buffer),
            "[IMU Data] Orient: x= %.2f, y= %.2f, z= %.2f ; Linear: x= %.2f, y= %.2f, z= %.2f\r\n",
            orient.x, orient.y, orient.z, linear.x, linear.y, linear.z);

    HAL_UART_Transmit(&huart3, (uint8_t*) buffer, strlen(buffer), HAL_MAX_DELAY);
    HAL_Delay(100); // 10 Hz
}
/* USER CODE END 0 */

2. Call the function inside the main loop to continuously fetch and transmit data:

/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
    /* USER CODE END WHILE */
    send_imu_data();
    /* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */

Step 10: Circuit Connections

To connect the BNO055 IMU sensor to the STM32 NUCLEO-H7A3ZI-Q, use the following wiring:

BNO055 Pin	NUCLEO Pin
Vin	3V3
GND	GND
SDA	SDA (PB9)
SCL	SCL (PB8)

Ensure the connections are secure to avoid communication issues. The image below illustrates the wiring:

For more detailed information about the external header connections of the NUCLEO-H7A3ZI-Q, refer to the image below:

Tools

• IDE: STM32CubeIDE (1.16.1)
• Microcontroller: STM32 NUCLEO-H7A3ZI-Q
• IMU Sensor: Adafruit 9-DOF Absolute Orientation IMU Fusion Breakout - BNO055

Third-Party Code

This project uses code from the bno055_stm32 repository, licensed under the MIT License. The original copyright belongs to Ivy Knob and contributors.