microbit: add accelerometer implementation

Signed-off-by: deadprogram <ron@hybridgroup.com>

examples/microbit_accelerometer.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"gobot.io/x/gobot"
+	"gobot.io/x/gobot/platforms/ble"
+	"gobot.io/x/gobot/platforms/microbit"
+)
+
+func main() {
+	bleAdaptor := ble.NewClientAdaptor(os.Args[1])
+	ubit := microbit.NewAccelerometerDriver(bleAdaptor)
+
+	work := func() {
+		ubit.On(microbit.Accelerometer, func(data interface{}) {
+			fmt.Println("Accelerometer", data)
+		})
+	}
+
+	robot := gobot.NewRobot("buttonBot",
+		[]gobot.Connection{bleAdaptor},
+		[]gobot.Device{ubit},
+		work,
+	)
+
+	robot.Start()
+}

examples/microbit_buttons_leds.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"fmt"
 	"os"
 
 	"gobot.io/x/gobot"
@@ -16,7 +15,6 @@ func main() {
 
 	work := func() {
 		buttons.On(microbit.ButtonA, func(data interface{}) {
-			fmt.Println("a", data)
 			if data.([]byte)[0] == 1 {
 				leds.UpLeftArrow()
 				return
@@ -26,7 +24,6 @@ func main() {
 		})
 
 		buttons.On(microbit.ButtonB, func(data interface{}) {
-			fmt.Println("b", data)
 			if data.([]byte)[0] == 1 {
 				leds.UpRightArrow()
 				return

platforms/microbit/accelerometer_driver.go

@@ -0,0 +1,92 @@
+package microbit
+
+import (
+	"bytes"
+	"encoding/binary"
+
+	"gobot.io/x/gobot"
+	"gobot.io/x/gobot/platforms/ble"
+)
+
+// AccelerometerDriver is the Gobot driver for the Microbit's built-in accelerometer
+type AccelerometerDriver struct {
+	name       string
+	connection gobot.Connection
+	gobot.Eventer
+}
+
+type RawAccelerometerData struct {
+	X int16
+	Y int16
+	Z int16
+}
+
+type AccelerometerData struct {
+	X float32
+	Y float32
+	Z float32
+}
+
+const (
+	// BLE services
+	accelerometerService = "e95d0753251d470aa062fa1922dfa9a8"
+
+	// BLE characteristics
+	accelerometerCharacteristic = "e95dca4b251d470aa062fa1922dfa9a8"
+
+	// Accelerometer event
+	Accelerometer = "accelerometer"
+)
+
+// NewAccelerometerDriver creates a Microbit AccelerometerDriver
+func NewAccelerometerDriver(a *ble.ClientAdaptor) *AccelerometerDriver {
+	n := &AccelerometerDriver{
+		name:       gobot.DefaultName("Microbit Accelerometer"),
+		connection: a,
+		Eventer:    gobot.NewEventer(),
+	}
+
+	n.AddEvent(Accelerometer)
+
+	return n
+}
+
+// Connection returns the BLE connection
+func (b *AccelerometerDriver) Connection() gobot.Connection { return b.connection }
+
+// Name returns the Driver Name
+func (b *AccelerometerDriver) Name() string { return b.name }
+
+// SetName sets the Driver Name
+func (b *AccelerometerDriver) SetName(n string) { b.name = n }
+
+// adaptor returns BLE adaptor
+func (b *AccelerometerDriver) adaptor() *ble.ClientAdaptor {
+	return b.Connection().(*ble.ClientAdaptor)
+}
+
+// Start tells driver to get ready to do work
+func (b *AccelerometerDriver) Start() (err error) {
+	// subscribe to button A notifications
+	b.adaptor().Subscribe(accelerometerCharacteristic, func(data []byte, e error) {
+		a := &RawAccelerometerData{X: 0, Y: 0, Z: 0}
+
+		buf := bytes.NewBuffer(data)
+		binary.Read(buf, binary.LittleEndian, &a.X)
+		binary.Read(buf, binary.LittleEndian, &a.Y)
+		binary.Read(buf, binary.LittleEndian, &a.Z)
+
+		result := &AccelerometerData{X: float32(a.X) / 1000.0,
+			Y: float32(a.Y) / 1000.0,
+			Z: float32(a.Z) / 1000.0}
+
+		b.Publish(b.Event(Accelerometer), result)
+	})
+
+	return
+}
+
+// Halt stops LED driver (void)
+func (b *AccelerometerDriver) Halt() (err error) {
+	return
+}

platforms/microbit/accelerometer_driver_test.go

@@ -0,0 +1,23 @@
+package microbit
+
+import (
+	"strings"
+	"testing"
+
+	"gobot.io/x/gobot"
+	"gobot.io/x/gobot/gobottest"
+
+	"gobot.io/x/gobot/platforms/ble"
+)
+
+var _ gobot.Driver = (*AccelerometerDriver)(nil)
+
+func initTestAccelerometerDriver() *AccelerometerDriver {
+	d := NewAccelerometerDriver(ble.NewClientAdaptor("D7:99:5A:26:EC:38"))
+	return d
+}
+
+func TestAccelerometerDriver(t *testing.T) {
+	d := initTestAccelerometerDriver()
+	gobottest.Assert(t, strings.HasPrefix(d.Name(), "Microbit Accelerometer"), true)
+}