PKGBUILD/pkg/sensor/ds18b20.go

package sensor

import (
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"sync"

	"git.cryptic.systems/volker.raschek/flucky/pkg/internal/format"
	"git.cryptic.systems/volker.raschek/flucky/pkg/types"
	uuid "github.com/satori/go.uuid"
)

// DS18B20 is a sensor to measure humidity and temperature.
type DS18B20 struct {
	*types.Sensor
	mutex *sync.Mutex
}

// Read measured values
func (ds18b20 *DS18B20) Read() ([]*types.MeasuredValue, error) {

	// Lock multiple access
	ds18b20.mutex.Lock()
	defer ds18b20.mutex.Unlock()

	if ds18b20.WireID == nil {
		return nil, fmt.Errorf("WireID is not specified")
	}

	socketPath := filepath.Join("/sys/bus/w1/devices", *ds18b20.WireID, "/w1_slave")
	if _, err := os.Stat(socketPath); os.IsNotExist(err) {
		return nil, fmt.Errorf("Socket path not found: %v", socketPath)
	}

	data, err := ioutil.ReadFile(socketPath)
	if err != nil {
		return nil, fmt.Errorf("Can not read data from sensor %v", ds18b20.Name)
	}

	raw := string(data)

	i := strings.LastIndex(raw, "t=")
	if i == -1 {
		return nil, errorReadData
	}

	c, err := strconv.ParseFloat(raw[i+2:len(raw)-1], 64)
	if err != nil {
		return nil, errorParseData
	}

	temperatureValue := c / 1000

	measuredValues := []*types.MeasuredValue{
		{
			ID:        uuid.NewV4().String(),
			Value:     float64(temperatureValue),
			ValueType: types.Temperature,
			Date:      format.FormatedTime(),
			SensorID:  ds18b20.ID,
		},
	}

	return measuredValues, nil
}