Merge branch 'master' of https://github.com/kid0m4n/go-rpi

README.md

@@ -31,3 +31,9 @@ Use various sensors on the RaspberryPi with Golang (like a ninja!)
   Ultrasonic proximity sensor
 
   [Documentation](http://godoc.org/github.com/kid0m4n/go-rpi/sensor/us020) [Product Page](http://www.digibay.in/sensor/object-detection-and-proximity?product_id=239)
+
+### BH1750FVI
+
+  Luminosity sensor
+
+  [Documentation](http://godoc.org/github.com/kid0m4n/go-rpi/sensor/us020) [Datasheet](http://www.elechouse.com/elechouse/images/product/Digital%20light%20Sensor/bh1750fvi-e.pdf)

samples/bh1750fvi.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"log"
+	"time"
+
+	"github.com/kid0m4n/go-rpi/i2c"
+	"github.com/kid0m4n/go-rpi/sensor/bh1750fvi"
+)
+
+func main() {
+	bus, err := i2c.NewBus(1)
+	if err != nil {
+		log.Panic(err)
+	}
+
+	lightingSensor := bh1750fvi.New(bh1750fvi.High, bus)
+	defer lightingSensor.Close()
+
+	for {
+		lighting, err := lightingSensor.Lighting()
+		if err != nil {
+			log.Panic(err)
+		}
+		log.Printf("Lighting is %v lx", lighting)
+
+		time.Sleep(500 * time.Millisecond)
+	}
+}

sensor/bh1750fvi/bh1750fvi.go

@@ -0,0 +1,171 @@
+// Package BH1750FVI allows interfacing with the BH1750FVI ambient light sensor through I2C protocol.
+package bh1750fvi
+
+import (
+	"log"
+	"sync"
+	"time"
+
+	"github.com/kid0m4n/go-rpi/i2c"
+)
+
+//accuracy = sensorValue/actualValue] (min = 0.96, typ = 1.2, max = 1.44
+const (
+	High  = "H"
+	High2 = "H2"
+
+	measurementAcuuracy = 1.2
+	defReadReg          = 0x00
+
+	sensorI2cAddr = 0x23
+
+	highResOpCode      = 0x10
+	highResMode2OpCode = 0x11
+
+	pollDelay = 150
+)
+
+// A BH1750FVI interface implements access to the sensor.
+type BH1750FVI interface {
+	// Run starts continuous sensor data acquisition loop.
+	Run() error
+
+	// Lighting returns the ambient lighting in lx.
+	Lighting() (lighting float64, err error)
+
+	// Close.
+	Close()
+
+	// SetPollDelay sets the delay between run of data acquisition loop.
+	SetPollDelay(delay int)
+}
+
+type bh1750fvi struct {
+	bus i2c.Bus
+	mu  *sync.RWMutex
+
+	lightingReadings chan float64
+	quit             chan bool
+
+	i2cAddr       byte
+	operationCode byte
+
+	poll int
+}
+
+// Default instance for BH1750FVI sensor
+var Default = New(High, i2c.Default)
+
+// Supports three modes:
+// "H" -> High resolution mode (1lx), takes 120ms (recommended).
+// "H2" -> High resolution mode 2 (0.5lx), takes 120ms (only use for low light).
+
+// New creates a new BH1750FVI interface according to the mode passed.
+func New(mode string, bus i2c.Bus) BH1750FVI {
+	switch mode {
+	case High:
+		return &bh1750fvi{bus: bus, i2cAddr: sensorI2cAddr, operationCode: highResOpCode, mu: new(sync.RWMutex)}
+	case High2:
+		return &bh1750fvi{bus: bus, i2cAddr: sensorI2cAddr, operationCode: highResMode2OpCode, mu: new(sync.RWMutex)}
+	default:
+		return &bh1750fvi{bus: bus, i2cAddr: sensorI2cAddr, operationCode: highResOpCode, mu: new(sync.RWMutex)}
+	}
+}
+
+// NewHighMode returns a BH1750FVI inteface on high resolution mode (1lx resolution)
+func NewHighMode(bus i2c.Bus) BH1750FVI {
+	return New(High, bus)
+}
+
+// NewHighMode returns a BH1750FVI inteface on high resolution mode2 (0.5lx resolution)
+func NewHigh2Mode(bus i2c.Bus) BH1750FVI {
+	return New(High2, bus)
+}
+
+func (d *bh1750fvi) measureLighting() (lighting float64, err error) {
+	err = d.bus.WriteByte(d.i2cAddr, d.operationCode)
+	if err != nil {
+		log.Print("bh1750fvi: Failed to initialize sensor")
+		return
+	}
+	time.Sleep(180 * time.Millisecond)
+
+	var sensorReading int
+	if sensorReading, err = d.bus.ReadInt(d.i2cAddr, defReadReg); err != nil {
+		return
+	}
+
+	lighting = float64(sensorReading) / measurementAcuuracy
+	return
+}
+
+// Lighting returns the ambient lighting in lx.
+func (d *bh1750fvi) Lighting() (lighting float64, err error) {
+	select {
+	case lighting = <-d.lightingReadings:
+		return
+	default:
+		return d.measureLighting()
+	}
+}
+
+// Run starts continuous sensor data acquisition loop.
+func (d *bh1750fvi) Run() (err error) {
+	go func() {
+		d.quit = make(chan bool)
+
+		timer := time.Tick(time.Duration(d.poll) * time.Millisecond)
+
+		var lighting float64
+
+		for {
+			select {
+			case d.lightingReadings <- lighting:
+			case <-timer:
+				if l, err := d.measureLighting(); err == nil {
+					lighting = l
+				}
+				if err == nil && d.lightingReadings == nil {
+					d.lightingReadings = make(chan float64)
+				}
+			case <-d.quit:
+				d.lightingReadings = nil
+				return
+			}
+		}
+	}()
+	return
+}
+
+// Close.
+func (d *bh1750fvi) Close() {
+	if d.quit != nil {
+		d.quit <- true
+	}
+	return
+}
+
+// SetPollDelay sets the delay between run of data acquisition loop.
+func (d *bh1750fvi) SetPollDelay(delay int) {
+	d.poll = delay
+}
+
+// SetPollDelay sets the delay between run of data acquisition loop.
+func SetPollDelay(delay int) {
+	Default.SetPollDelay(delay)
+}
+
+// Lighting returns the ambient lighting in lx.
+func Lighting() (lighting float64, err error) {
+	return Default.Lighting()
+}
+
+// Run starts continuous sensor data acquisition loop.
+func Run() (err error) {
+	return Default.Run()
+}
+
+// Close.
+func Close() {
+	Default.Close()
+}