bmi270: add driver for BMI270 6-axis IMU

bmi270/bmi270.go

@@ -0,0 +1,238 @@
+// Package bmi270 provides a driver for the BMI270 6-axis inertial measurement unit.
+//
+// Datasheet: https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bmi270-ds000.pdf
+package bmi270
+
+import (
+	_ "embed"
+	"errors"
+	"time"
+
+	"tinygo.org/x/drivers"
+)
+
+// BMI270 configuration file (firmware blob) provided by Bosch Sensortec.
+// Source: https://github.com/boschsensortec/BMI270_SensorAPI
+// License: BSD 3-Clause "New" or "Revised" License
+// Copyright (c) Bosch Sensortec GmbH. All rights reserved.
+//
+//go:embed bmi270-config.bin
+var bmi270ConfigData string
+
+const Address = 0x68
+
+type AccelRange uint8
+
+const (
+	Accel2G  AccelRange = 0x00
+	Accel4G  AccelRange = 0x01
+	Accel8G  AccelRange = 0x02
+	Accel16G AccelRange = 0x03
+)
+
+type GyroRange uint8
+
+const (
+	Gyro2000DPS GyroRange = 0x00
+	Gyro1000DPS GyroRange = 0x01
+	Gyro500DPS  GyroRange = 0x02
+	Gyro250DPS  GyroRange = 0x03
+	Gyro125DPS  GyroRange = 0x04
+)
+
+type Device struct {
+	bus        drivers.I2C
+	address    uint8
+	accelRange AccelRange
+	gyroRange  GyroRange
+	wbuf       [17]byte
+	rbuf       [6]byte
+}
+
+type Config struct {
+	AccelRange AccelRange
+	GyroRange  GyroRange
+}
+
+func DefaultConfig() Config {
+	return Config{
+		AccelRange: Accel2G,
+		GyroRange:  Gyro2000DPS,
+	}
+}
+
+var (
+	errNotConnected = errors.New("bmi270: not connected")
+	errInitFailed   = errors.New("bmi270: initialization failed")
+)
+
+func NewI2C(bus drivers.I2C, address uint8) *Device {
+	return &Device{
+		bus:     bus,
+		address: address,
+	}
+}
+
+func (d *Device) Connected() bool {
+	val, err := d.read1(reg_CHIP_ID)
+	return err == nil && val == chipIDBMI270
+}
+
+func (d *Device) Configure(config Config) error {
+	d.accelRange = config.AccelRange
+	d.gyroRange = config.GyroRange
+
+	if !d.Connected() {
+		return errNotConnected
+	}
+
+	if err := d.write1(reg_CMD, 0xB6); err != nil {
+		return err
+	}
+	time.Sleep(200 * time.Millisecond)
+
+	if err := d.write1(reg_PWR_CONF, 0x00); err != nil {
+		return err
+	}
+	time.Sleep(1 * time.Millisecond)
+
+	if err := d.write1(reg_INIT_CTRL, 0x00); err != nil {
+		return err
+	}
+	time.Sleep(1 * time.Millisecond)
+
+	chunkSize := 16
+	for i := 0; i < len(bmi270ConfigData); i += chunkSize {
+		end := i + chunkSize
+		if end > len(bmi270ConfigData) {
+			end = len(bmi270ConfigData)
+		}
+
+		wordAddr := uint16(i / 2)
+		addrLow := byte(wordAddr & 0x0F)
+		addrHigh := byte(wordAddr >> 4)
+		d.wbuf[0] = reg_INIT_ADDR_0
+		d.wbuf[1] = addrLow
+		d.wbuf[2] = addrHigh
+		if err := d.bus.Tx(uint16(d.address), d.wbuf[:3], nil); err != nil {
+			return err
+		}
+
+		n := copy(d.wbuf[1:], bmi270ConfigData[i:end])
+		d.wbuf[0] = reg_INIT_DATA
+		if err := d.bus.Tx(uint16(d.address), d.wbuf[:1+n], nil); err != nil {
+			return err
+		}
+	}
+
+	if err := d.write1(reg_INIT_CTRL, 0x01); err != nil {
+		return err
+	}
+	time.Sleep(200 * time.Millisecond)
+
+	start := time.Now()
+	for {
+		status, err := d.read1(reg_INTERNAL_STATUS)
+		if err != nil {
+			return err
+		}
+		if status&0x07 == 0x01 {
+			break
+		}
+		if time.Since(start) >= 500*time.Millisecond {
+			return errInitFailed
+		}
+		time.Sleep(50 * time.Millisecond)
+	}
+
+	if err := d.write1(reg_ACC_CONF, 0xA8); err != nil {
+		return err
+	}
+
+	if err := d.write1(reg_ACC_RANGE, byte(d.accelRange)); err != nil {
+		return err
+	}
+
+	if err := d.write1(reg_GYR_CONF, 0xA8); err != nil {
+		return err
+	}
+
+	if err := d.write1(reg_GYR_RANGE, byte(d.gyroRange)); err != nil {
+		return err
+	}
+
+	if err := d.write1(reg_PWR_CTRL, 0x06); err != nil {
+		return err
+	}
+	time.Sleep(50 * time.Millisecond)
+
+	return nil
+}
+
+// ReadAcceleration returns the acceleration in µg (micro-gravity).
+// When one of the axes is pointing straight down and the sensor
+// is not moving, the returned value will be around 1000000.
+func (d *Device) ReadAcceleration() (x, y, z int32, err error) {
+	if err = d.bus.Tx(uint16(d.address), []byte{reg_ACC_DATA}, d.rbuf[:6]); err != nil {
+		return 0, 0, 0, err
+	}
+
+	rawX := int16(uint16(d.rbuf[1])<<8 | uint16(d.rbuf[0]))
+	rawY := int16(uint16(d.rbuf[3])<<8 | uint16(d.rbuf[2]))
+	rawZ := int16(uint16(d.rbuf[5])<<8 | uint16(d.rbuf[4]))
+
+	k := int32(61)
+	switch d.accelRange {
+	case Accel4G:
+		k = 122
+	case Accel8G:
+		k = 244
+	case Accel16G:
+		k = 488
+	}
+
+	x = int32(rawX) * k
+	y = int32(rawY) * k
+	z = int32(rawZ) * k
+	return
+}
+
+// ReadRotation returns the angular velocity in µdps (micro-degrees/second).
+func (d *Device) ReadRotation() (x, y, z int32, err error) {
+	if err = d.bus.Tx(uint16(d.address), []byte{reg_GYR_DATA}, d.rbuf[:6]); err != nil {
+		return 0, 0, 0, err
+	}
+
+	rawX := int16(uint16(d.rbuf[1])<<8 | uint16(d.rbuf[0]))
+	rawY := int16(uint16(d.rbuf[3])<<8 | uint16(d.rbuf[2]))
+	rawZ := int16(uint16(d.rbuf[5])<<8 | uint16(d.rbuf[4]))
+
+	k := int32(60976)
+	switch d.gyroRange {
+	case Gyro1000DPS:
+		k = 30488
+	case Gyro500DPS:
+		k = 15244
+	case Gyro250DPS:
+		k = 7622
+	case Gyro125DPS:
+		k = 3811
+	}
+
+	x = int32(rawX) * k
+	y = int32(rawY) * k
+	z = int32(rawZ) * k
+	return
+}
+
+func (d *Device) read1(register uint8) (uint8, error) {
+	d.wbuf[0] = register
+	err := d.bus.Tx(uint16(d.address), d.wbuf[:1], d.rbuf[:1])
+	return d.rbuf[0], err
+}
+
+func (d *Device) write1(register, val uint8) error {
+	d.wbuf[0] = register
+	d.wbuf[1] = val
+	return d.bus.Tx(uint16(d.address), d.wbuf[:2], nil)
+}

bmi270/registers.go

@@ -0,0 +1,21 @@
+package bmi270
+
+const (
+	reg_CHIP_ID         = 0x00
+	reg_ACC_DATA        = 0x0C
+	reg_GYR_DATA        = 0x12
+	reg_INTERNAL_STATUS = 0x21
+	reg_ACC_CONF        = 0x40
+	reg_ACC_RANGE       = 0x41
+	reg_GYR_CONF        = 0x42
+	reg_GYR_RANGE       = 0x43
+	reg_INIT_CTRL       = 0x59
+	reg_INIT_ADDR_0     = 0x5B
+	reg_INIT_ADDR_1     = 0x5C // automatically updated when writing 2 bytes to INIT_ADDR_0
+	reg_INIT_DATA       = 0x5E
+	reg_PWR_CONF        = 0x7C
+	reg_PWR_CTRL        = 0x7D
+	reg_CMD             = 0x7E
+
+	chipIDBMI270 = 0x24
+)

examples/bmi270/main.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/bmi270"
+)
+
+func main() {
+	time.Sleep(5 * time.Second)
+
+	machine.I2C0.Configure(machine.I2CConfig{
+		SCL: machine.SCL0_PIN,
+		SDA: machine.SDA0_PIN,
+	})
+
+	sensor := bmi270.NewI2C(machine.I2C0, bmi270.Address)
+	if !sensor.Connected() {
+		println("BMI270 not connected")
+		return
+	}
+
+	cfg := bmi270.DefaultConfig()
+	if err := sensor.Configure(cfg); err != nil {
+		println("BMI270 configuration failed:", err.Error())
+		return
+	}
+
+	for {
+		time.Sleep(time.Second)
+
+		accelX, accelY, accelZ, err := sensor.ReadAcceleration()
+		if err != nil {
+			println("Error reading acceleration:", err.Error())
+			continue
+		}
+		println("acc (mg):", accelX/1000, accelY/1000, accelZ/1000)
+
+		gyroX, gyroY, gyroZ, err := sensor.ReadRotation()
+		if err != nil {
+			println("Error reading rotation:", err.Error())
+			continue
+		}
+		println("gyr (mdps):", gyroX/1000, gyroY/1000, gyroZ/1000)
+	}
+}

smoketest.sh

@@ -17,6 +17,7 @@ tinygo build -size short -o ./build/test.hex -target=itsybitsy-m0 ./examples/bh1
 tinygo build -size short -o ./build/test.hex -target=itsybitsy-m0 ./examples/blinkm/main.go
 tinygo build -size short -o ./build/test.hex -target=pinetime     ./examples/bma42x/main.go
 tinygo build -size short -o ./build/test.hex -target=itsybitsy-m0 ./examples/bmi160/main.go
+tinygo build -size short -o ./build/test.elf -target=m5stack-core2 ./examples/bmi270/main.go
 tinygo build -size short -o ./build/test.hex -target=itsybitsy-m0 ./examples/bmp180/main.go
 tinygo build -size short -o ./build/test.hex -target=itsybitsy-m0 ./examples/bmp280/main.go
 tinygo build -size short -o ./build/test.hex -target=trinket-m0 ./examples/bmp388/main.go