Adding support for hmc8553l compass

README.md

@@ -275,6 +275,7 @@ drivers provided using the `gobot/drivers/i2c` package:
 	- GrovePi Expansion Board
 	- Grove RGB LCD
 	- HMC6352 Compass
+	- HMC8553L 3-Axis Digital Compass
 	- INA3221 Voltage Monitor
 	- JHD1313M1 LCD Display w/RGB Backlight
 	- L3GD20H 3-Axis Gyroscope

ROADMAP.md

@@ -36,7 +36,6 @@ https://github.com/hybridgroup/gobot/issues
 
 - ensure that SMBUS operations are working as expected.
 - add support for the following i2c devices:
-   - HMC5883L
    - LSM303DLHC
    - MAG3110
    - MMA8452

drivers/i2c/README.md

@@ -27,6 +27,7 @@ Gobot has a extensible system for connecting to hardware devices. The following
 - GrovePi Expansion Board
 - Grove RGB LCD
 - HMC6352 Compass
+- HMC8553L 3-Axis Digital Compass
 - INA3221 Voltage Monitor
 - JHD1313M1 LCD Display w/RGB Backlight
 - L3GD20H 3-Axis Gyroscope

drivers/i2c/hmc8553l_driver.go

@@ -0,0 +1,120 @@
+package i2c
+
+import (
+	"math"
+
+	"gobot.io/x/gobot"
+)
+
+const (
+	defaultAddress = 0x1e // default I2C Address
+	registerA      = 0x0  // Address of Configuration register A
+	registerB      = 0x01 // Address of Configuration register B
+	registerMode   = 0x02 // Address of node register
+	xAxisH         = 0x03 // Address of X-axis MSB data register
+	zAxisH         = 0x05 // Address of Z-axis MSB data register
+	yAxisH         = 0x07 // Address of Y-axis MSB data register
+)
+
+// HMC8553LDriver is a Driver for a HMC6352 digital compass
+type HMC8553LDriver struct {
+	name       string
+	connector  Connector
+	connection Connection
+	Config
+}
+
+// NewHMC8553LDriver creates a new driver with specified i2c interface
+// Params:
+//		conn Connector - the Adaptor to use with this Driver
+//
+// Optional params:
+//		i2c.WithBus(int):	bus to use with this driver
+//		i2c.WithAddress(int):	address to use with this driver
+//
+func NewHMC8553LDriver(a Connector, options ...func(Config)) *HMC8553LDriver {
+	hmc := &HMC8553LDriver{
+		name:      gobot.DefaultName("HMC8553L"),
+		connector: a,
+		Config:    NewConfig(),
+	}
+
+	for _, option := range options {
+		option(hmc)
+	}
+
+	return hmc
+}
+
+// Name returns the name for this Driver
+func (h *HMC8553LDriver) Name() string { return h.name }
+
+// SetName sets the name for this Driver
+func (h *HMC8553LDriver) SetName(n string) { h.name = n }
+
+// Connection returns the connection for this Driver
+func (h *HMC8553LDriver) Connection() gobot.Connection { return h.connector.(gobot.Connection) }
+
+// Start initializes the HMC8553L
+func (h *HMC8553LDriver) Start() (err error) {
+	bus := h.GetBusOrDefault(h.connector.GetDefaultBus())
+	address := h.GetAddressOrDefault(defaultAddress)
+	h.connection, err = h.connector.GetConnection(address, bus)
+	if err != nil {
+		return err
+	}
+	if err := h.connection.WriteByteData(registerA, 0x70); err != nil {
+		return err
+	}
+	if err := h.connection.WriteByteData(registerB, 0xa0); err != nil {
+		return err
+	}
+	if err := h.connection.WriteByteData(registerMode, 0); err != nil {
+		return err
+	}
+	return
+}
+
+// Halt returns true if devices is halted successfully
+func (h *HMC8553LDriver) Halt() (err error) { return }
+
+// ReadRawData reads the raw values from the X, Y, and Z registers
+func (h *HMC8553LDriver) ReadRawData() (x int16, y int16, z int16, err error) {
+	unsignedX, err := h.connection.ReadWordData(xAxisH)
+	if err != nil {
+		return
+	}
+	unsignedY, err := h.connection.ReadWordData(yAxisH)
+	if err != nil {
+		return
+	}
+	unsignedZ, err := h.connection.ReadWordData(zAxisH)
+	if err != nil {
+		return
+	}
+	return unsignedToSigned(unsignedX), unsignedToSigned(unsignedY), unsignedToSigned(unsignedZ), nil
+}
+
+// Heading returns the current heading in radians
+func (h *HMC8553LDriver) Heading() (heading float64, err error) {
+	var x, y int16
+	x, y, _, err = h.ReadRawData()
+	if err != nil {
+		return
+	}
+	heading = math.Atan2(float64(y), float64(x))
+	if heading > 2*math.Pi {
+		heading -= 2 * math.Pi
+	}
+	if heading < 0 {
+		heading += 2 * math.Pi
+	}
+	return
+}
+
+func unsignedToSigned(unsignedValue uint16) int16 {
+	if unsignedValue > 32768 {
+		return int16(unsignedValue) - ^int16(0) - ^int16(0) - 2
+	}
+	return int16(unsignedValue)
+}

drivers/i2c/hmc8553l_driver_test.go

@@ -0,0 +1,72 @@
+package i2c
+
+import (
+	"errors"
+	"testing"
+
+	"gobot.io/x/gobot"
+	"gobot.io/x/gobot/gobottest"
+)
+
+var _ gobot.Driver = (*HMC8553LDriver)(nil)
+
+// --------- HELPERS
+func initTestHMC8553LDriver() (driver *HMC8553LDriver) {
+	driver, _ = initTestHMC8553LDriverWithStubbedAdaptor()
+	return
+}
+
+func initTestHMC8553LDriverWithStubbedAdaptor() (*HMC8553LDriver, *i2cTestAdaptor) {
+	adaptor := newI2cTestAdaptor()
+	return NewHMC8553LDriver(adaptor), adaptor
+}
+
+// --------- TESTS
+
+func TestNewHMC8553LDriver(t *testing.T) {
+	// Does it return a pointer to an instance of HMC8553LDriver?
+	var bm interface{} = NewHMC8553LDriver(newI2cTestAdaptor())
+	_, ok := bm.(*HMC8553LDriver)
+	if !ok {
+		t.Errorf("NewHMC8553LDriver() should have returned a *HMC8553LDriver")
+	}
+
+	b := NewHMC8553LDriver(newI2cTestAdaptor())
+	gobottest.Refute(t, b.Connection(), nil)
+}
+
+// Methods
+func TestHMC8553LDriverStart(t *testing.T) {
+	hmc, adaptor := initTestHMC8553LDriverWithStubbedAdaptor()
+
+	gobottest.Assert(t, hmc.Start(), nil)
+
+	adaptor.i2cWriteImpl = func([]byte) (int, error) {
+		return 0, errors.New("write error")
+	}
+	err := hmc.Start()
+	gobottest.Assert(t, err, errors.New("write error"))
+}
+
+func Test8553LStartConnectError(t *testing.T) {
+	d, adaptor := initTestHMC8553LDriverWithStubbedAdaptor()
+	adaptor.Testi2cConnectErr(true)
+	gobottest.Assert(t, d.Start(), errors.New("Invalid i2c connection"))
+}
+
+func TestHMC8553LDriverHalt(t *testing.T) {
+	hmc := initTestHMC8553LDriver()
+
+	gobottest.Assert(t, hmc.Halt(), nil)
+}
+
+func TestHMC8553LDriverSetName(t *testing.T) {
+	d := initTestHMC8553LDriver()
+	d.SetName("TESTME")
+	gobottest.Assert(t, d.Name(), "TESTME")
+}
+
+func TestHMC8553LDriverOptions(t *testing.T) {
+	d := NewHMC8553LDriver(newI2cTestAdaptor(), WithBus(2))
+	gobottest.Assert(t, d.GetBusOrDefault(1), 2)
+}

examples/raspi_hmc8553l.go

@@ -0,0 +1,46 @@
+// +build example
+//
+// Do not build by default.
+
+/*
+ How to run
+
+	go run examples/firmata_hmc8553l.go
+*/
+
+package main
+
+import (
+	"fmt"
+	"time"
+
+	"gobot.io/x/gobot"
+	"gobot.io/x/gobot/drivers/i2c"
+	"gobot.io/x/gobot/platforms/raspi"
+)
+
+func main() {
+	raspi := raspi.NewAdaptor()
+	hmc8553l := i2c.NewHMC8553LDriver(raspi)
+
+	work := func() {
+		gobot.Every(200*time.Millisecond, func() {
+
+			// get heading in radians, to convert to degrees multiply by 180/math.Pi
+			heading, _ := hmc8553l.Heading()
+			fmt.Println("Heading", heading)
+
+			// read the raw data from the device, this is useful for calibration
+			x, y, z, _ := hmc8553l.ReadRawData()
+			fmt.Println(x, y, z)
+		})
+	}
+
+	robot := gobot.NewRobot("hmc8553LBot",
+		[]gobot.Connection{raspi},
+		[]gobot.Device{hmc8553l},
+		work,
+	)
+
+	robot.Start()
+}