Add grove temperature sensor driver

platforms/gpio/grove_temperature_sensor_driver.go

@@ -0,0 +1,107 @@
+package gpio
+
+import (
+	"math"
+	"time"
+
+	"github.com/hybridgroup/gobot"
+)
+
+var _ gobot.Driver = (*GroveTemperatureSensorDriver)(nil)
+
+// GroveTemperatureSensorDriver represents a Temperature Sensor
+type GroveTemperatureSensorDriver struct {
+	name        string
+	pin         string
+	halt        chan bool
+	temperature float64
+	interval    time.Duration
+	connection  AnalogReader
+	gobot.Eventer
+}
+
+// NewGroveTemperatureSensorDriver returns a new GroveTemperatureSensorDriver with a polling interval of
+// 10 Milliseconds given an AnalogReader, name and pin.
+//
+// Optinally accepts:
+// 	time.Duration: Interval at which the TemperatureSensor is polled for new information
+//
+// Adds the following API Commands:
+// 	"Read" - See AnalogSensor.Read
+func NewGroveTemperatureSensorDriver(a AnalogReader, name string, pin string, v ...time.Duration) *GroveTemperatureSensorDriver {
+	d := &GroveTemperatureSensorDriver{
+		name:       name,
+		connection: a,
+		pin:        pin,
+		Eventer:    gobot.NewEventer(),
+		interval:   10 * time.Millisecond,
+		halt:       make(chan bool),
+	}
+
+	if len(v) > 0 {
+		d.interval = v[0]
+	}
+
+	d.AddEvent(Data)
+	d.AddEvent(Error)
+
+	return d
+}
+
+// Start starts the GroveTemperatureSensorDriver and reads the Sensor at the given interval.
+// Emits the Events:
+//	Data int - Event is emitted on change and represents the current temperature in celsius from the sensor.
+//	Error error - Event is emitted on error reading from the sensor.
+func (a *GroveTemperatureSensorDriver) Start() (errs []error) {
+	thermistor := 3975.0
+	a.temperature = 0
+
+	go func() {
+		for {
+			rawValue, err := a.Read()
+
+			resistance := float64(1023.0-rawValue) * 10000 / float64(rawValue)
+			newValue := 1/(math.Log(resistance/10000.0)/thermistor+1/298.15) - 273.15
+
+			if err != nil {
+				gobot.Publish(a.Event(Error), err)
+			} else if newValue != a.temperature && newValue != -1 {
+				a.temperature = newValue
+				gobot.Publish(a.Event(Data), a.temperature)
+			}
+			select {
+			case <-time.After(a.interval):
+			case <-a.halt:
+				return
+			}
+		}
+	}()
+	return
+}
+
+// Halt stops polling the analog sensor for new information
+func (a *GroveTemperatureSensorDriver) Halt() (errs []error) {
+	a.halt <- true
+	return
+}
+
+// Name returns the GroveTemperatureSensorDrivers name
+func (a *GroveTemperatureSensorDriver) Name() string { return a.name }
+
+// Pin returns the GroveTemperatureSensorDrivers pin
+func (a *GroveTemperatureSensorDriver) Pin() string { return a.pin }
+
+// Connection returns the GroveTemperatureSensorDrivers Connection
+func (a *GroveTemperatureSensorDriver) Connection() gobot.Connection {
+	return a.connection.(gobot.Connection)
+}
+
+// Read returns the current Temperature from the Sensor
+func (a *GroveTemperatureSensorDriver) Temperature() (val float64) {
+	return a.temperature
+}
+
+// Read returns the raw reading from the Sensor
+func (a *GroveTemperatureSensorDriver) Read() (val int, err error) {
+	return a.connection.AnalogRead(a.Pin())
+}