ble-sensors/lib/xiaomi/scale/scale_v2.go

package scale

import (
	"bytes"
	"encoding/binary"
	"log"
	"time"

	"github.com/go-ble/ble"
	influxdb2 "github.com/influxdata/influxdb-client-go"
	influxdb2_api "github.com/influxdata/influxdb-client-go/api"
	"go.uber.org/zap"
)

// XiaomiScaleV2UUID is BLE UUID for Xiaomi Scale V2
var XiaomiScaleV2UUID ble.UUID = []byte{0x1b, 0x18}

// ParseXiaomiScaleV2 parses V2 scale service data
func ParseXiaomiScaleV2(writeAPI *influxdb2_api.WriteAPI, logger *zap.Logger, timestamp time.Time, detector string, description string, advertisement ble.Advertisement, index int, sd ble.ServiceData) {

	var scaleData struct {
		RawUnit     uint8
		ControlByte uint8
		Year        uint16
		Month       uint8
		Day         uint8
		Hour        uint8
		Minute      uint8
		Second      uint8
		Impedance   uint16
		RawWeight   uint16
	}
	err := binary.Read(bytes.NewBuffer(sd.Data), binary.LittleEndian, &scaleData)
	if err != nil {
		panic(err)
	}

	isStabilized := (scaleData.ControlByte & (1 << 5)) != 0
	hasImpedance := (scaleData.ControlByte & (1 << 1)) != 0

	var originalUnit string
	var weight float64

	switch scaleData.RawUnit {
	case 3:
		originalUnit = "lbs"
		weight = float64(scaleData.RawWeight) / 100.0 * 0.453592

	case 2:
		originalUnit = "kg"
		weight = float64(scaleData.RawWeight) / 200.0

	default:
		originalUnit = "unknown"
		weight = float64(scaleData.RawWeight)
	}

	if isStabilized {
		loc, err := time.LoadLocation("Local")
		if err != nil {
			log.Fatal(err)
		}
		scaleTimestamp := time.Date(
			int(scaleData.Year),
			time.Month(scaleData.Month),
			int(scaleData.Day),
			int(scaleData.Hour),
			int(scaleData.Minute),
			int(scaleData.Second),
			0,
			loc)
		difference := timestamp.Sub(scaleTimestamp)

		point := influxdb2.NewPointWithMeasurement("weight")
		point.SetTime(scaleTimestamp)
		if detector != "" {
			point.AddTag("detector", detector)
		}
		point.AddTag("address", advertisement.Addr().String())
		if description != "" {
			point.AddTag("description", description)
		}
		point.AddTag("unit", "kg")
		point.AddTag("original_unit", originalUnit)
		point.AddField("time_difference", difference.Seconds())
		point.AddField("value", weight)
		if hasImpedance {
			point.AddField("impedance", scaleData.Impedance)
		}
		(*writeAPI).WritePoint(point)

		logger.Debug("xiaomi v2 scale",
			zap.String("name", advertisement.LocalName()),
			zap.String("source", advertisement.Addr().String()),
			zap.String("description", description),
			zap.Bool("is_stabilized", isStabilized),
			zap.Bool("has_impedance", hasImpedance),
			zap.Float64("weight", weight))

	}

}