PKGBUILD/pkg/sensor/ds18b20.go

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package sensor
import (
"context"
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"fmt"
"io/ioutil"
"path/filepath"
"strconv"
"strings"
"sync"
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"time"
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"github.com/go-flucky/flucky/pkg/types"
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uuid "github.com/satori/go.uuid"
)
// DS18B20 is a sensor to measure humidity and temperature.
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type DS18B20 struct {
*types.Sensor
}
// GetSensorModel returns the sensor model
func (s *DS18B20) GetSensorModel() types.SensorModel {
return s.Sensor.SensorModel
}
// Read measured values
func (s *DS18B20) Read() ([]*types.MeasuredValue, error) {
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if s.WireID == nil {
return nil, fmt.Errorf("WireID is not specified for sensor %v", s.Name())
}
data, err := ioutil.ReadFile(filepath.Join("/sys/bus/w1/devices", *s.WireID, "/w1_slave"))
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if err != nil {
return nil, fmt.Errorf("Can not read data from sensor %v", s.SensorName)
}
raw := string(data)
i := strings.LastIndex(raw, "t=")
if i == -1 {
return nil, ErrReadSensor
}
c, err := strconv.ParseFloat(raw[i+2:len(raw)-1], 64)
if err != nil {
return nil, ErrParseData
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}
temperatureValue := c / 1000
measuredValues := []*types.MeasuredValue{
&types.MeasuredValue{
ID: uuid.NewV4().String(),
Value: float64(temperatureValue),
ValueType: types.MeasuredValueTypeTemperature,
FromDate: time.Now(),
TillDate: time.Now(),
SensorID: s.SensorID,
},
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}
return measuredValues, nil
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}
// ReadChannel reads the measured values from the sensor and writes them to a
// channel.
func (s *DS18B20) ReadChannel(measuredValuesChannel chan<- []*types.MeasuredValue, errorChannel chan<- error, wg *sync.WaitGroup) {
if wg != nil {
defer wg.Done()
}
measuredValues, err := s.Read()
if err != nil {
errorChannel <- err
return
}
measuredValuesChannel <- measuredValues
}
// ReadContinously reads the measured values continously from the sensor and
// writes them to a channel.
func (s *DS18B20) ReadContinously(ctx context.Context, measuredValuesChannel chan<- []*types.MeasuredValue, errorChannel chan<- error) {
for {
select {
case <-ctx.Done():
errorChannel <- fmt.Errorf("%v: Context closed: %v", s.SensorName, ctx.Err())
return
default:
s.ReadChannel(measuredValuesChannel, errorChannel, nil)
}
}
}