BNO055

A userspace I²C driver for the Bosch BNO055 9-axis Absolute Orientation Sensor.

Install

Use go get to install the latest version of the library:

go get github.com/kpeu3i/bno055@v1.0.0

Next, include bno055 in your application:

import "github.com/kpeu3i/bno055"

Usage

First, connect the sensor via I²C interface.

package main

import (
	"fmt"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/kpeu3i/bno055"
)

func main() {
	sensor, err := bno055.NewSensor(0x28, 1)
	if err != nil {
		panic(err)
	}

	err = sensor.UseExternalCrystal(true)
	if err != nil {
		panic(err)
	}

	status, err := sensor.Status()
	if err != nil {
		panic(err)
	}

	fmt.Printf("*** Status: system=%v, system_error=%v, self_test=%v\n", status.System, status.SystemError, status.SelfTest)

	revision, err := sensor.Revision()
	if err != nil {
		panic(err)
	}

	fmt.Printf(
		"*** Revision: software=%v, bootloader=%v, accelerometer=%v, gyroscope=%v, magnetometer=%v\n",
		revision.Software,
		revision.Bootloader,
		revision.Accelerometer,
		revision.Gyroscope,
		revision.Magnetometer,
	)

	axisConfig, err := sensor.AxisConfig()
	if err != nil {
		panic(err)
	}

	fmt.Printf(
		"*** Axis: x=%v, y=%v, z=%v, sign_x=%v, sign_y=%v, sign_z=%v\n",
		axisConfig.X,
		axisConfig.Y,
		axisConfig.Z,
		axisConfig.SignX,
		axisConfig.SignY,
		axisConfig.SignZ,
	)

	temperature, err := sensor.Temperature()
	if err != nil {
		panic(err)
	}

	fmt.Printf("*** Temperature: t=%v\n", temperature)

	signals := make(chan os.Signal, 1)
	signal.Notify(signals, syscall.SIGINT, syscall.SIGTERM)

	for {
		select {
		case <-signals:
			err := sensor.Close()
			if err != nil {
				panic(err)
			}
		default:
			vector, err := sensor.Euler()
			if err != nil {
				panic(err)
			}

			fmt.Printf("\r*** Euler angles: x=%5.3f, y=%5.3f, z=%5.3f", vector.X, vector.Y, vector.Z)
		}

		time.Sleep(100 * time.Millisecond)
	}

	// Output:
	// *** Status: system=133, system_error=0, self_test=15
	// *** Revision: software=785, bootloader=21, accelerometer=251, gyroscope=15, magnetometer=50
	// *** Axis: x=0, y=1, z=2, sign_x=0, sign_y=0, sign_z=0
	// *** Temperature: t=27
	// *** Euler angles: x=2.312, y=2.000, z=91.688
}

Troubleshooting

How to enable I²C bus on RPi device?

If you employ RaspberryPI, use raspi-config utility to activate i2c-bus on the OS level. Go to "Interfacing Options" menu, to active I²C bus. Probably you will need to reboot to load I²C kernel module. Finally you should have device like /dev/i2c-1 present in the system.

How to find I²C bus allocation and device address?

Use i2cdetect utility in format "i2cdetect -y X", where X may vary from 0 to 5 or more, to discover address occupied by peripheral device. To install utility you should run apt install i2c-tools on debian-kind system. i2cdetect -y 1 sample output:

         0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
    00:          -- -- -- -- -- -- -- -- -- -- -- -- --
    10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    20: -- -- -- -- -- -- -- -- 28 -- -- -- -- -- -- --
    30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    70: -- -- -- -- -- -- -- --

Workaround for I²C clock stretching

It seems all versions of Raspberry Pi have an I²C bus hardware problem preventing them from working correctly with Bosch BNO055. The problem has been variously diagnosed as being due to the Pi’s inability to handle clock stretching in arbitrary parts of the I²C transaction and the BNO055 chip’s exquisite sensitivity to I²C bus levels.

Solutions:

1. Configuring software I²C driver

   Raspbian has a software I²C driver that can be enabled by adding the following line to /boot/config.txt:

   dtoverlay=i2c-gpio,bus=3
   

   This will create an I²C bus called /dev/i2c-3. SDA will be on GPIO23 and SCL will be on GPIO24 which are pins 16 and 18 on the GPIO header respectively.

2. Slowing the I²C bus transactions

   The solution require slowing the I²C bus transactions to 25 kb/s, by inserting a line in the /boot/config.txt file:

   dtparam=i2c_arm_baudrate=25000
   

TODO

• Docs
• Tests