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

package scale

import (
	"bytes"
	"encoding/binary"
	"fmt"
	"log"
	"os"
	"sync"
	"time"

	"github.com/currantlabs/ble"
	influxdb2 "github.com/influxdata/influxdb-client-go"
	influxdb2_api "github.com/influxdata/influxdb-client-go/api"
)

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

// ParseXiaomiScaleV2 parses V2 scale service data
func ParseXiaomiScaleV2(mux *sync.Mutex, writeAPI *influxdb2_api.WriteAPI, advertisement ble.Advertisement, index int, sd ble.ServiceData) {
	timestamp := time.Now()

	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("sensor")
		point.SetTime(scaleTimestamp)
		hostname, _ := os.Hostname()
		if hostname != "" {
			point.AddTag("detector", hostname)
		}
		point.AddTag("address", advertisement.Address().String())
		point.AddTag("weight_unit", "kg")
		point.AddTag("original_weight_unit", originalUnit)
		point.AddField("rssi", advertisement.RSSI())
		point.AddField("weight", weight)
		if hasImpedance {
			point.AddField("impedance", scaleData.Impedance)
		}
		(*writeAPI).WritePoint(point)

		mux.Lock()
		fmt.Printf("*******************************************\n")
		fmt.Printf("Xiaomi V2 Scale\n")
		fmt.Printf("[%s] %3d:\n", advertisement.Address(), advertisement.RSSI())
		if len(advertisement.LocalName()) > 0 {
			fmt.Printf(" Name: %s\n", advertisement.LocalName())
		}
		if len(advertisement.Services()) > 0 {
			fmt.Printf(" Svcs: %v\n", advertisement.Services())
		}
		if len(advertisement.ManufacturerData()) > 0 {
			fmt.Printf(" MD: %v\n", advertisement.ManufacturerData())
		}
		fmt.Printf(" rawUnit: %d\n", scaleData.RawUnit)
		fmt.Printf(" Control byte: %d %b\n", scaleData.ControlByte, scaleData.ControlByte)
		fmt.Printf(" Control byte X: %d\n", scaleData.ControlByte&^(1<<5)&^(1<<1))
		fmt.Printf(" Is stabilized:  %v\n", isStabilized)
		fmt.Printf(" Has impedance: %v\n", hasImpedance)
		fmt.Printf(" Year: %d\n", scaleData.Year)
		fmt.Printf(" Month: %d\n", scaleData.Month)
		fmt.Printf(" Day: %v\n", scaleData.Day)
		fmt.Printf(" Hour: %d\n", scaleData.Hour)
		fmt.Printf(" Minute: %d\n", scaleData.Minute)
		fmt.Printf(" Second: %d\n", scaleData.Second)
		fmt.Printf(" Measurement taken %s ago\n", difference)
		fmt.Printf(" Impedance: %d\n", scaleData.Impedance)
		fmt.Printf(" Raw weight: %d\n", scaleData.RawWeight)
		fmt.Printf(" Weight: %f %s\n", weight, originalUnit)
		fmt.Printf("*******************************************\n")
		mux.Unlock()
	}

}