module: setup project structure, document and add utilities

common/common.go

@@ -0,0 +1,125 @@
+package common
+
+import (
+	"encoding/binary"
+	"errors"
+	"math"
+	"strconv"
+	"strings"
+
+	"github.com/currantlabs/gatt"
+)
+
+type VersionBatteryResponse struct {
+	FirmwareVersion string // as "x.y.z"
+	BatteryLevel    uint8  // in percent 0-100
+}
+
+type SensorDataResponse struct {
+	Temperature  float64 // in degree C
+	Brightness   uint32  // in lux
+	Moisture     uint8   // in percent 0-100
+	Conductivity uint16  // in µS/cm
+}
+
+func MifloraGetModeChangeData() []byte {
+	return []byte{0xa0, 0x1f}
+}
+
+var MifloraServiceUUID = gatt.MustParseUUID("00001204-0000-1000-8000-00805f9b34fb")
+var MifloraCharModeChangeUUID = gatt.MustParseUUID("00001a00-0000-1000-8000-00805f9b34fb")
+var MifloraCharReadSensorDataUUID = gatt.MustParseUUID("00001a01-0000-1000-8000-00805f9b34fb")
+var MifloraCharVersionBatteryUUID = gatt.MustParseUUID("00001a02-0000-1000-8000-00805f9b34fb")
+
+func FindServiceByUUID(services []*gatt.Service, u gatt.UUID) *gatt.Service {
+	for _, service := range services {
+		if service.UUID().Equal(u) {
+			return service
+		}
+	}
+	return nil
+}
+
+func FindCharacteristicByUUID(characteristics []*gatt.Characteristic, u gatt.UUID) *gatt.Characteristic {
+	for _, characteristic := range characteristics {
+		if characteristic.UUID().Equal(u) {
+			return characteristic
+		}
+	}
+	return nil
+}
+
+func MifloraRequestVersionBattery(p gatt.Peripheral) (VersionBatteryResponse, error) {
+	mifloraService := FindServiceByUUID(p.Services(), MifloraServiceUUID)
+	if mifloraService == nil {
+		return VersionBatteryResponse{}, errors.New("Failed to get the miflora service")
+	}
+
+	mifloraVersionBatteryChar := FindCharacteristicByUUID(mifloraService.Characteristics(), MifloraCharVersionBatteryUUID)
+	if mifloraVersionBatteryChar == nil {
+		return VersionBatteryResponse{}, errors.New("Failed to get the version battery characteristic")
+	}
+
+	bytes, err := p.ReadCharacteristic(mifloraVersionBatteryChar)
+	if err != nil {
+		return VersionBatteryResponse{}, err
+	}
+
+	return VersionBatteryResponse{string(bytes[2:]), uint8(bytes[0])}, nil
+}
+
+func MifloraRequestModeChange(p gatt.Peripheral) error {
+	mifloraService := FindServiceByUUID(p.Services(), MifloraServiceUUID)
+	if mifloraService == nil {
+		return errors.New("Failed to get the miflora service")
+	}
+
+	mifloraModeChangeChar := FindCharacteristicByUUID(mifloraService.Characteristics(), MifloraCharModeChangeUUID)
+	if mifloraModeChangeChar == nil {
+		return errors.New("Failed to discover the mode change characteristic")
+	}
+
+	err := p.WriteCharacteristic(mifloraModeChangeChar, MifloraGetModeChangeData(), false)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func MifloraRequstSensorData(p gatt.Peripheral) (SensorDataResponse, error) {
+	mifloraService := FindServiceByUUID(p.Services(), MifloraServiceUUID)
+	if mifloraService == nil {
+		return SensorDataResponse{}, errors.New("Failed to get the miflora service")
+	}
+
+	mifloraSensorDataChar := FindCharacteristicByUUID(mifloraService.Characteristics(), MifloraCharReadSensorDataUUID)
+	if mifloraSensorDataChar == nil {
+		return SensorDataResponse{}, errors.New("Failed to discover the sensor data characteristic")
+	}
+
+	bytes, err := p.ReadCharacteristic(mifloraSensorDataChar)
+	if err != nil {
+		return SensorDataResponse{}, err
+	}
+
+	return SensorDataResponse{
+		Temperature:  float64(binary.LittleEndian.Uint16(bytes[0:2])) / 10.0,
+		Brightness:   binary.LittleEndian.Uint32(bytes[3:7]),
+		Moisture:     uint8(bytes[7]),
+		Conductivity: binary.LittleEndian.Uint16(bytes[8:10]),
+	}, nil
+}
+
+func (res VersionBatteryResponse) NumericFirmwareVersion() int {
+	// turns "2.3.4" into 20304
+	version := 0
+	parts := strings.Split(res.FirmwareVersion, ".")
+	for i, part := range parts {
+		partNumber, err := strconv.Atoi(part)
+		if err != nil {
+			version += int(math.Pow10((len(parts)-(i+1))*2)) * partNumber
+		}
+	}
+	return version
+}