[ble] Able to connect and retrieve battery notifications

examples/ble_minidrone.go

@@ -1,8 +1,6 @@
 package main
 
 import (
-	"fmt"
-	"time"
 	"os"
 
 	"github.com/hybridgroup/gobot"
@@ -16,7 +14,7 @@ func main() {
 	drone := ble.NewBLEMinidroneDriver(bleAdaptor, "drone")
 
 	work := func() {
-		battery.Init()
+		drone.Init()
 	}
 
 	robot := gobot.NewRobot("bleBot",

platforms/ble/ble_adaptor.go

@@ -108,7 +108,8 @@ func (b *BLEAdaptor) WriteCharacteristic(sUUID string, cUUID string, data []byte
 	}
 
 	characteristic := b.services[sUUID].characteristics[cUUID]
-	err = b.peripheral.WriteCharacteristic(characteristic, data, false)
+
+	err = b.peripheral.WriteCharacteristic(characteristic, data, true)
 	if err != nil {
 		fmt.Printf("Failed to write characteristic, err: %s\n", err)
 		return err
@@ -117,6 +118,29 @@ func (b *BLEAdaptor) WriteCharacteristic(sUUID string, cUUID string, data []byte
 	return
 }
 
+// SubscribeNotify subscribes to the BLE device for the
+// requested service and characteristic
+func (b *BLEAdaptor) SubscribeNotify(sUUID string, cUUID string, f func([]byte, error)) (err error) {
+	if !b.connected {
+		log.Fatalf("Cannot subscribe to BLE device until connected")
+		return
+	}
+
+	characteristic := b.services[sUUID].characteristics[cUUID]
+
+	fn := func(c *gatt.Characteristic, b []byte, err error) {
+		f(b, err)
+	}
+
+	err = b.peripheral.SetNotifyValue(characteristic, fn)
+	if err != nil {
+		fmt.Printf("Failed to subscribe to characteristic, err: %s\n", err)
+		return err
+	}
+
+	return
+}
+
 func (b *BLEAdaptor) StateChangeHandler(d gatt.Device, s gatt.State) {
 	fmt.Println("State:", s)
 	switch s {

platforms/ble/minidrone.go

@@ -1,7 +1,7 @@
 package ble
 
 import (
-	//"bytes"
+	"fmt"
 
 	"github.com/hybridgroup/gobot"
 )
@@ -46,6 +46,12 @@ func (b *BLEMinidroneDriver) Halt() (errs []error) { return }
 func (b *BLEMinidroneDriver) Init() (err error) {
 	b.stepsfa0b++
 	buf := []byte{0x04, byte(b.stepsfa0b), 0x00, 0x04, 0x01, 0x00, 0x32, 0x30, 0x31, 0x34, 0x2D, 0x31, 0x30, 0x2D, 0x32, 0x38, 0x00}
-	err = b.adaptor().WriteCharacteristic("fa00", "fa0b", buf)
+	err = b.adaptor().WriteCharacteristic("9a66fa000800919111e4012d1540cb8e", "9a66fa0b0800919111e4012d1540cb8e", buf)
+
+	f := func(b []byte, e error) {
+			fmt.Printf("battery: %d\n", b[len(b)-1])
+	}
+
+	b.adaptor().SubscribeNotify("9a66fb000800919111e4012d1540cb8e", "9a66fb0f0800919111e4012d1540cb8e", f)
 	return err
 }