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lsm9ds1: minimal implementation
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‎examples/lsm9ds1/main.go‎

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// LSM9DS1, 9 axis Inertial Measurement Unit (IMU)
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package main
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import (
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"fmt"
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"machine"
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"time"
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"tinygo.org/x/drivers/lsm9ds1"
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)
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const (
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PLOTTER = false
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SHOW_ACCELERATION = true
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SHOW_ROTATION = true
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SHOW_MAGNETIC_FIELD = true
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SHOW_TEMPERATURE = true
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)
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func main() {
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// I2C configure
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machine.I2C0.Configure(machine.I2CConfig{})
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// LSM9DS1 setup
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device := lsm9ds1.New(machine.I2C0)
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err := device.Configure(lsm9ds1.Configuration{
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AccelRange: lsm9ds1.ACCEL_2G,
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AccelSampleRate: lsm9ds1.ACCEL_SR_119,
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GyroRange: lsm9ds1.GYRO_250DPS,
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GyroSampleRate: lsm9ds1.GYRO_SR_119,
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MagRange: lsm9ds1.MAG_4G,
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MagSampleRate: lsm9ds1.MAG_SR_40,
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})
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if err != nil {
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for {
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println("Failed to configure", err.Error())
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time.Sleep(time.Second)
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}
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}
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for {
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if con, err := device.Connected(); !con || err != nil {
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println("LSM9DS1 not connected")
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time.Sleep(time.Second)
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continue
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}
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ax, ay, az, _ := device.ReadAcceleration()
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gx, gy, gz, _ := device.ReadRotation()
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mx, my, mz, _ := device.ReadMagneticField()
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t, _ := device.ReadTemperature()
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if PLOTTER {
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printPlotter(ax, ay, az, gx, gy, gz, mx, my, mz, t)
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time.Sleep(time.Millisecond * 100)
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} else {
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printMonitor(ax, ay, az, gx, gy, gz, mx, my, mz, t)
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time.Sleep(time.Millisecond * 1000)
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}
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}
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}
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// Arduino IDE's Serial Plotter
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func printPlotter(ax, ay, az, gx, gy, gz, mx, my, mz, t int32) {
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if SHOW_ACCELERATION {
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fmt.Printf("AX:%f, AY:%f, AZ:%f,", axis(ax), axis(ay), axis(az))
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}
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if SHOW_ROTATION {
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fmt.Printf("GX:%f, GY:%f, GZ:%f,", axis(gx), axis(gy), axis(gz))
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}
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if SHOW_MAGNETIC_FIELD {
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fmt.Printf("MX:%d, MY:%d, MZ:%d,", mx, my, mz)
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}
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if SHOW_TEMPERATURE {
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fmt.Printf("T:%f", float32(t)/1000)
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}
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println()
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}
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// Any Serial Monitor
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func printMonitor(ax, ay, az, gx, gy, gz, mx, my, mz, t int32) {
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if SHOW_ACCELERATION {
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fmt.Printf("Acceleration (g): %f, %f, %f\r\n", axis(ax), axis(ay), axis(az))
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}
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if SHOW_ROTATION {
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fmt.Printf("Rotation (dps): %f, %f, %f\r\n", axis(gx), axis(gy), axis(gz))
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}
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if SHOW_MAGNETIC_FIELD {
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fmt.Printf("Magnetic field (nT): %d, %d, %d\r\n", mx, my, mz)
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}
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if SHOW_TEMPERATURE {
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fmt.Printf("Temperature C: %f\r\n", float32(t)/1000)
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}
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println()
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}
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func axis(raw int32) float32 {
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return float32(raw) / 1000000
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}

‎lsm9ds1/lsm9ds1.go‎

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// LSM9DS1, 9 axis Inertial Measurement Unit (IMU)
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//
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// Datasheet: https://www.st.com/resource/en/datasheet/lsm6ds3.pdf
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//
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package lsm9ds1 // import "tinygo.org/x/drivers/lsm9ds1"
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import (
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"errors"
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"tinygo.org/x/drivers"
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)
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type AccelRange uint8
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type AccelSampleRate uint8
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type AccelBandwidth uint8
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type GyroRange uint8
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type GyroSampleRate uint8
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type MagRange uint8
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type MagSampleRate uint8
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// Device wraps connection to a LSM9DS1 device.
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type Device struct {
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bus drivers.I2C
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AccelAddress uint8
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MagAddress uint8
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accelMultiplier int32
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gyroMultiplier int32
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magMultiplier int32
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dataBufferSix []uint8
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dataBufferTwo []uint8
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}
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// Configuration for LSM9DS1 device.
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type Configuration struct {
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AccelRange AccelRange
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AccelSampleRate AccelSampleRate
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AccelBandWidth AccelBandwidth
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GyroRange GyroRange
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GyroSampleRate GyroSampleRate
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MagRange MagRange
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MagSampleRate MagSampleRate
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}
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var errNotConnected = errors.New("lsm9ds1: failed to communicate with either acel/gyro or magnet sensor")
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// New creates a new LSM9DS1 connection. The I2C bus must already be configured.
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//
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// This function only creates the Device object, it does not touch the device.
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func New(bus drivers.I2C) *Device {
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return &Device{
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bus: bus,
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AccelAddress: ACCEL_ADDRESS,
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MagAddress: MAG_ADDRESS,
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dataBufferSix: make([]uint8, 6),
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dataBufferTwo: make([]uint8, 2),
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}
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}
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// Connected returns whether both sensor on LSM9DS1 has been found.
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// It does two "who am I" requests and checks the responses.
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// In a rare case of an I2C bus issue, it can also return an error.
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// Case of boolean false and error nil means I2C is up,
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// but "who am I" responses have unexpected values.
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func (d *Device) Connected() (connected bool, err error) {
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data1, data2 := []byte{0}, []byte{0}
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err = d.bus.ReadRegister(d.AccelAddress, WHO_AM_I, data1)
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if err != nil {
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return false, err
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}
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err = d.bus.ReadRegister(d.MagAddress, WHO_AM_I_M, data2)
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if err != nil {
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return false, err
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}
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return data1[0] == 0x68 && data2[0] == 0x3D, nil
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}
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// ReadAcceleration reads the current acceleration from the device and returns
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// it in µg (micro-gravity). When one of the axes is pointing straight to Earth
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// and the sensor is not moving the returned value will be around 1000000 or
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// -1000000.
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func (d *Device) ReadAcceleration() (x, y, z int32, err error) {
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err = d.bus.ReadRegister(uint8(d.AccelAddress), OUT_X_L_XL, d.dataBufferSix)
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if err != nil {
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return
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}
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x = int32(int16((uint16(d.dataBufferSix[1])<<8)|uint16(d.dataBufferSix[0]))) * d.accelMultiplier
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y = int32(int16((uint16(d.dataBufferSix[3])<<8)|uint16(d.dataBufferSix[2]))) * d.accelMultiplier
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z = int32(int16((uint16(d.dataBufferSix[5])<<8)|uint16(d.dataBufferSix[4]))) * d.accelMultiplier
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return
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}
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// ReadRotation reads the current rotation from the device and returns it in
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// µ°/s (micro-degrees/sec). This means that if you were to do a complete
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// rotation along one axis and while doing so integrate all values over time,
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// you would get a value close to 360000000.
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func (d *Device) ReadRotation() (x, y, z int32, err error) {
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err = d.bus.ReadRegister(uint8(d.AccelAddress), OUT_X_L_G, d.dataBufferSix)
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if err != nil {
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return
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}
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x = int32(int16((uint16(d.dataBufferSix[1])<<8)|uint16(d.dataBufferSix[0]))) * d.gyroMultiplier
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y = int32(int16((uint16(d.dataBufferSix[3])<<8)|uint16(d.dataBufferSix[2]))) * d.gyroMultiplier
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z = int32(int16((uint16(d.dataBufferSix[5])<<8)|uint16(d.dataBufferSix[4]))) * d.gyroMultiplier
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return
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}
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// ReadMagneticField reads the current magnetic field from the device and returns
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// it in nT (nanotesla). 1 G (gauss) = 100_000 nT (nanotesla).
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func (d *Device) ReadMagneticField() (x, y, z int32, err error) {
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err = d.bus.ReadRegister(uint8(d.MagAddress), OUT_X_L_M, d.dataBufferSix)
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if err != nil {
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return
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}
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x = int32(int16((int16(d.dataBufferSix[1])<<8)|int16(d.dataBufferSix[0]))) * d.magMultiplier
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y = int32(int16((int16(d.dataBufferSix[3])<<8)|int16(d.dataBufferSix[2]))) * d.magMultiplier
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z = int32(int16((int16(d.dataBufferSix[5])<<8)|int16(d.dataBufferSix[4]))) * d.magMultiplier
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return
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}
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// ReadTemperature returns the temperature in Celsius milli degrees (°C/1000)
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func (d *Device) ReadTemperature() (t int32, err error) {
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err = d.bus.ReadRegister(uint8(d.AccelAddress), OUT_TEMP_L, d.dataBufferTwo)
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if err != nil {
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return
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}
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// From "Table 5. Temperature sensor characteristics"
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// temp = value/16 + 25
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t = 25000 + (int32(int16((int16(d.dataBufferTwo[1])<<8)|int16(d.dataBufferTwo[0])))*125)/2
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return
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}
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// --- end of public methods --------------------------------------------------
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// doConfigure is called by public Configure methods after all
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// necessary board-specific initialisations are taken care of
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func (d *Device) doConfigure(cfg Configuration) (err error) {
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// Verify unit communication
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if con, err := d.Connected(); !con || err != nil {
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return errNotConnected
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}
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// Multipliers come from "Table 3. Sensor characteristics" of the datasheet * 1000
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switch cfg.AccelRange {
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case ACCEL_2G:
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d.accelMultiplier = 61
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case ACCEL_4G:
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d.accelMultiplier = 122
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case ACCEL_8G:
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d.accelMultiplier = 244
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case ACCEL_16G:
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d.accelMultiplier = 732
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}
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switch cfg.GyroRange {
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case GYRO_250DPS:
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d.gyroMultiplier = 8750
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case GYRO_500DPS:
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d.gyroMultiplier = 17500
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case GYRO_2000DPS:
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d.gyroMultiplier = 70000
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}
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switch cfg.MagRange {
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case MAG_4G:
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d.magMultiplier = 14
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case MAG_8G:
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d.magMultiplier = 29
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case MAG_12G:
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d.magMultiplier = 43
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case MAG_16G:
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d.magMultiplier = 58
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}
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data := make([]byte, 1)
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// Configure accelerometer
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// Sample rate & measurement range
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data[0] = uint8(cfg.AccelSampleRate)<<5 | uint8(cfg.AccelRange)<<3
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err = d.bus.WriteRegister(d.AccelAddress, CTRL_REG6_XL, data)
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if err != nil {
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return
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}
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// Configure gyroscope
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// Sample rate & measurement range
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data[0] = uint8(cfg.GyroSampleRate)<<5 | uint8(cfg.GyroRange)<<3
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err = d.bus.WriteRegister(d.AccelAddress, CTRL_REG1_G, data)
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if err != nil {
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return
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}
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// Configure magnetometer
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// Temperature compensation enabled
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// High-performance mode XY axis
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// Sample rate
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data[0] = 0b10000000 | 0b01000000 | uint8(cfg.MagSampleRate)<<2
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err = d.bus.WriteRegister(d.MagAddress, CTRL_REG1_M, data)
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if err != nil {
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return
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}
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// Measurement range
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data[0] = uint8(cfg.MagRange) << 5
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err = d.bus.WriteRegister(d.MagAddress, CTRL_REG2_M, data)
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if err != nil {
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return
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}
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// Continuous-conversion mode
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// https://electronics.stackexchange.com/questions/237397/continuous-conversion-vs-single-conversion-mode
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data[0] = 0b00000000
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err = d.bus.WriteRegister(d.MagAddress, CTRL_REG3_M, data)
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if err != nil {
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return
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}
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// High-performance mode Z axis
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data[0] = 0b00001000
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err = d.bus.WriteRegister(d.MagAddress, CTRL_REG4_M, data)
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if err != nil {
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return
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}
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return nil
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}

‎lsm9ds1/lsm9ds1_generic.go‎

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//go:build !nano_33_ble
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// +build !nano_33_ble
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package lsm9ds1
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// Configure sets up the device for communication.
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func (d *Device) Configure(cfg Configuration) error {
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return d.doConfigure(cfg)
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}

‎lsm9ds1/lsm9ds1_nano_33_ble.go‎

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//go:build nano_33_ble
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// +build nano_33_ble
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// Nano 33 BLE [Sense] has LSM9DS1 unit on-board.
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// This custom Configure function powers unit up
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// and enables I2C, so unit can can be accessed.
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package lsm9ds1
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import (
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"machine"
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"time"
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)
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// Configure sets up the device for communication.
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func (d *Device) Configure(cfg Configuration) error {
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// Following lines are Nano 33 BLE specific, they have nothing to do with sensor per se
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machine.LSM_PWR.Configure(machine.PinConfig{Mode: machine.PinOutput})
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machine.LSM_PWR.High()
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machine.I2C_PULLUP.Configure(machine.PinConfig{Mode: machine.PinOutput})
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machine.I2C_PULLUP.High()
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// Wait a moment
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time.Sleep(10 * time.Millisecond)
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// Common initialisation code
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return d.doConfigure(cfg)
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}

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