Decorator for ble service added

workers/scaleworker.go

@@ -0,0 +1,142 @@
+package workers
+
+import (
+	"fmt"
+	"log"
+	"math"
+	"strings"
+	"time"
+
+	"github.com/currantlabs/gatt"
+)
+
+type Weight struct {
+	Time   time.Time
+	Weight float64
+}
+
+type Scale struct {
+	Worker
+}
+
+var WEIGHT_MEASUREMENT_SERVICE = gatt.MustParseUUID("181d")
+var WEIGHT_MEASUREMENT_HISTORY_CHARACTERISTIC = gatt.MustParseUUID("00002a2f-0000-3512-2118-0009af100700")
+var WEIGHT_MEASUREMENT_TIME_CHARACTERISTIC = gatt.MustParseUUID("2a2b")
+var WEIGHT_MEASUREMENT_CONFIG = gatt.MustParseUUID("2902")
+
+func (s Scale) OnDiscovery(p gatt.Peripheral, a *gatt.Advertisement, rssi int) bool {
+	ID := p.ID()
+	if !strings.HasPrefix(ID, "88:0F:10") {
+		return false
+	}
+
+	return true
+}
+
+func (s Scale) OnConnect(p gatt.Peripheral, err error) error {
+	ID := p.ID()
+	//not our device
+	if !strings.HasPrefix(ID, "88:0F:10") {
+		return nil
+	}
+
+	fmt.Println("Connected")
+	defer p.Device().CancelConnection(p)
+
+	if err := p.SetMTU(500); err != nil {
+		fmt.Printf("Failed to set MTU, err: %s\n", err)
+	}
+	fmt.Printf("Set mtu done.\n")
+
+	// Discovery services
+	services, err := p.DiscoverServices(nil)
+	fmt.Printf("Services: %v+", services)
+	if err != nil {
+		fmt.Printf("Failed to discover services, err: %s\n", err)
+		return nil
+	}
+
+	service := getServiceByUUID(WEIGHT_MEASUREMENT_SERVICE, services)
+	fmt.Printf("Service Found %s\n", service.Name())
+	chars, _ := p.DiscoverCharacteristics(nil, service)
+
+	char := getCharByUUID(WEIGHT_MEASUREMENT_TIME_CHARACTERISTIC, chars)
+	b, err := p.ReadCharacteristic(char)
+	if err != nil {
+		fmt.Printf("Failed to read characteristic, err: %s\n", err)
+		return nil
+	}
+	fmt.Printf("    value         %x | %q\n", b, b)
+
+	histChar := getCharByUUID(WEIGHT_MEASUREMENT_HISTORY_CHARACTERISTIC, chars)
+	descriptors, _ := p.DiscoverDescriptors(nil, histChar)
+	descriptor := getDescriptorByUUID(WEIGHT_MEASUREMENT_CONFIG, descriptors)
+	p.WriteDescriptor(descriptor, []byte{0x02, 0x00})
+
+	p.SetNotifyValue(histChar, func(c *gatt.Characteristic, b []byte, e error) {
+		log.Printf("Got back from %s: %#x\n", c.UUID(), b)
+		//weight :=
+		if len(b) == 20 {
+			first := b[0:10]
+			parseData(first)
+			second := b[10:20]
+			parseData(second)
+		} else if len(b) == 10 {
+			parseData(b)
+		}
+	})
+	p.WriteCharacteristic(histChar, []byte{0x02}, true)
+
+	fmt.Printf("Waiting for 5 seconds to get some notifiations, if any.\n")
+	time.Sleep(10 * time.Second)
+
+	return nil
+}
+
+func parseData(weightBytes []byte) *Weight {
+	ctrlByte := weightBytes[0]
+
+	isWeightRemoved := isBitSet(ctrlByte, 7)
+	isStabilized := isBitSet(ctrlByte, 5)
+	isLBSUnit := isBitSet(ctrlByte, 0)
+	isCattyUnit := isBitSet(ctrlByte, 4)
+
+	// Only if the value is stabilized and the weight is *not* removed, the date is valid
+	if isStabilized && !isWeightRemoved {
+		wb4 := int(weightBytes[4])
+		wb3 := int(weightBytes[3])
+		year := (wb4<<8 | wb3)
+		month := int(weightBytes[5])
+		day := int(weightBytes[6])
+		hours := int(weightBytes[7])
+		min := int(weightBytes[8])
+		sec := int(weightBytes[9])
+
+		// Is the year plausible? Check if the year is in the range of 20 years...
+		now := time.Now()
+		if math.Abs(float64(now.Year()-year)) > 20 || year > now.Year() {
+			return nil
+		}
+
+		wb1 := int(weightBytes[1])
+		wb2 := int(weightBytes[2])
+		weightVal := 0.0
+		if isLBSUnit || isCattyUnit {
+			weightVal = float64(((wb2)<<8)|(wb1)) / 100.0
+		} else {
+			weightVal = float64(((wb2)<<8)|(wb1)) / 200.0
+		}
+
+		t := time.Date(year, time.Month(month), day, hours, min, sec, 0, time.Local)
+		weight := &Weight{Weight: weightVal, Time: t}
+
+		// fmt.Printf("Payload is: %#x\n", weightBytes)
+		fmt.Printf("[+] Year: %v, Month: %v, day: %v, hr: %v, min: %v, sec: %v = %v \n", year, month, day, hours, min, sec, weightVal)
+		return weight
+	}
+	return nil
+}
+
+func isBitSet(value byte, bit uint) bool {
+	return (value & (1 << bit)) != 0
+}