ble-sensors/lib/cleargrass/sensor.go

package cleargrass

import (
	"encoding/binary"
	"encoding/hex"
	"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"
)

// https://github.com/alexvenom/XiaomiCleargrassInkDislpay/blob/master/XiaomiClearGrassInk.js

// CleargrassUUID is the Bluetooth UUID for Cleargrass BLE sensor data
var CleargrassUUID ble.UUID = []byte{0xcd, 0xfd}

// ParseCleargrassSensorData .
func ParseCleargrassSensorData(writeAPI *influxdb2_api.WriteAPI, logger *zap.Logger, timestamp time.Time, detector string, description string, advertisement ble.Advertisement, index int, sd ble.ServiceData) {
	logger.Debug("cleargrass", zap.String("event_data", hex.Dump(sd.Data)),
		zap.Int("length", len(sd.Data)))
	for eventOffset := 8; eventOffset < len(sd.Data)-2; {
		eventType := sd.Data[eventOffset]
		eventLength := int(sd.Data[eventOffset+1])
		if eventOffset+eventLength > len(sd.Data) {
			logger.Warn("event length exceeds data length")
			return
		}
		eventData := sd.Data[eventOffset+2 : eventOffset+2+eventLength]
		eventOffset = eventOffset + 2 + eventLength

		switch eventType {
		case 0x01:
			if eventLength != 4 {
				logger.Warn("temperature/humidity event length should be 4",
					zap.String("event_data", hex.Dump(eventData)))
				continue
			}

			temperature := float64(binary.LittleEndian.Uint16(eventData[0:2])) / 10

			point := influxdb2.NewPointWithMeasurement("temperature")
			point.SetTime(timestamp)
			if detector != "" {
				point.AddTag("detector", detector)
			}
			point.AddTag("address", advertisement.Addr().String())
			if description != "" {
				point.AddTag("description", description)
			}
			point.AddTag("unit", "°C")
			point.AddField("value", temperature)
			(*writeAPI).WritePoint(point)

			logger.Debug("sending sensor reading",
				zap.String("source", advertisement.Addr().String()),
				zap.String("description", description),
				zap.String("measurement", "temperature"),
				zap.String("measurement_unit", "°C"),
				zap.Float64("value", temperature))

			humidity := float64(binary.LittleEndian.Uint16(eventData[2:4])) / 10

			point = influxdb2.NewPointWithMeasurement("humidity")
			point.SetTime(timestamp)
			if detector != "" {
				point.AddTag("detector", detector)
			}
			point.AddTag("address", advertisement.Addr().String())
			if description != "" {
				point.AddTag("description", description)
			}
			point.AddTag("unit", "%")
			point.AddField("value", humidity)
			(*writeAPI).WritePoint(point)

			logger.Debug("sending sensor reading",
				zap.String("source", advertisement.Addr().String()),
				zap.String("description", description),
				zap.String("measurement", "humidity"),
				zap.String("measurement_unit", "%"),
				zap.Float64("value", humidity))

		case 0x02:
			if eventLength != 1 {
				logger.Warn("battery event length should be 1")
				continue
			}

			battery := int(eventData[0])

			point := influxdb2.NewPointWithMeasurement("battery")
			point.SetTime(timestamp)
			if detector != "" {
				point.AddTag("detector", detector)
			}
			point.AddTag("address", advertisement.Addr().String())
			if description != "" {
				point.AddTag("description", description)
			}
			point.AddTag("unit", "%")
			point.AddField("value", battery)
			(*writeAPI).WritePoint(point)

			logger.Debug("sending sensor reading",
				zap.String("source", advertisement.Addr().String()),
				zap.String("description", description),
				zap.String("measurement", "battery"),
				zap.String("measurement_unit", "%"),
				zap.Int("value", battery))

		default:
			logger.Warn("unknown event type",
				zap.Uint8("event_type", eventType),
				zap.String("event_data", hex.Dump(eventData)))
		}
	}

}