Add initial support for isl29125 rgb sensor

samples/.gitignore

@@ -8,6 +8,7 @@ gpio
 gpiodetect
 gpiodirect
 gpioshort
+isl29125
 l3gd20
 led
 ledshort

samples/isl29125.go

@@ -0,0 +1,36 @@
+// +build ignore
+
+package main
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/kidoman/embd"
+	"github.com/kidoman/embd/sensor/isl29125"
+
+	_ "github.com/kidoman/embd/host/all"
+)
+
+func main() {
+
+	if err := embd.InitI2C(); err != nil {
+		panic(err)
+	}
+	defer embd.CloseI2C()
+
+	bus := embd.NewI2CBus(1)
+
+	isl := isl29125.New(isl29125.DefaultConfig, bus)
+	defer isl.Close()
+
+	for {
+		r, err := isl.Reading()
+		if err != nil {
+			panic(err)
+		}
+		fmt.Printf("%v", r)
+
+		time.Sleep(500 * time.Millisecond)
+	}
+}

sensor/isl29125/isl29125.go

@@ -0,0 +1,175 @@
+// Package isl29125 allows interfacing with the ISL29125 RGB light sensor
+// Datasheet: http://www.intersil.com/content/dam/Intersil/documents/isl2/isl29125.pdf
+package isl29125
+
+/*
+
+   TODO:
+       - improve constructor
+       - add support for config register 2 and 3
+       - add support for lux calculation
+*/
+
+import (
+	"time"
+
+	"github.com/golang/glog"
+	"github.com/kidoman/embd"
+)
+
+const (
+	sensorI2cAddr = 0x44
+
+	pollDelay = 250
+
+	deviceRegisterAddr = 0x00
+	conf1RegisterAddr  = 0x01
+	flagRegisterAdr    = 0x08
+)
+
+const (
+	ModePowerDown = 0x00
+	ModeGreenOnly = 0x01
+	ModeRedOnly   = 0x02
+	ModeBlueOnly  = 0x03
+	ModeStandBy   = 0x04
+	ModeRGB       = 0x05
+	ModeRG        = 0x06
+	ModeGB        = 0x07
+)
+
+const (
+	LuxRange375 = 0x00
+	LuxRange10k = 0x08
+)
+
+const (
+	Resolution16Bit = 0x00
+	Resolution12Bit = 0x10
+)
+
+const (
+	SyncStartOnWrite = 0x00
+	SyncStartOnInt   = 0x20
+)
+
+const (
+	RegisterGreenLow  = 0x09
+	RegisterGreenHigh = 0x0a
+	RegisterRedLow    = 0x0b
+	RegisterRedHigh   = 0x0c
+	RegisterBlueLow   = 0x0d
+	RegisterBlueHigh  = 0x0e
+)
+
+const (
+	FlagInterrupt           = 0x01
+	FlagConversion          = 0x02
+	FlagPowerDownOrBrownOut = 0x04
+	FlagGreenConverting     = 0x10
+	FlagRedConverting       = 0x20
+	FlagBlueConverting      = 0x30
+)
+
+const (
+	DefaultConfig = ModePowerDown | LuxRange375 | Resolution16Bit | SyncStartOnWrite
+)
+
+const (
+	DeviceID = 0x7d
+)
+
+// Reading represents a single reading from an RGB light sensor
+type Reading struct {
+	Red        uint16
+	Green      uint16
+	Blue       uint16
+	Lux        uint16
+	LuxRange   int
+	Resolution int
+}
+
+// ISL29125 represents an RGB light sensor
+type ISL29125 struct {
+	Bus  embd.I2CBus
+	Poll int
+
+	readings chan *Reading
+	quit     chan bool
+
+	mode       int
+	luxRange   int
+	resolution int
+	syncStart  int
+}
+
+// New returns an ISL29125 for a given config
+func New(config int, bus embd.I2CBus) *ISL29125 {
+	glog.Info("Creating new ISL29125")
+	return &ISL29125{Bus: bus, Poll: pollDelay}
+}
+
+func (i *ISL29125) getReading() (*Reading, error) {
+
+	glog.Info("Getting reading")
+	red, err := i.Bus.ReadWordFromReg(sensorI2cAddr, RegisterRedLow)
+	if err != nil {
+		return nil, err
+	}
+	green, err := i.Bus.ReadWordFromReg(sensorI2cAddr, RegisterGreenLow)
+	if err != nil {
+		return nil, err
+	}
+	blue, err := i.Bus.ReadWordFromReg(sensorI2cAddr, RegisterBlueLow)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Reading{Red: red, Green: green, Blue: blue}, nil
+}
+
+// Reading returns a single sensor reading
+func (i *ISL29125) Reading() (*Reading, error) {
+	select {
+	case r := <-i.readings:
+		return r, nil
+	default:
+		return i.getReading()
+	}
+}
+
+// Run starts continuous sensor data acquisition loop.
+func (i *ISL29125) Run() {
+	glog.Info("Running sensor")
+	go func() {
+		i.quit = make(chan bool)
+		i.readings = make(chan *Reading)
+		timer := time.Tick(time.Duration(i.Poll) * time.Millisecond)
+
+		var reading *Reading
+
+		for {
+			select {
+			case i.readings <- reading:
+			case <-timer:
+				r, err := i.getReading()
+				if err == nil {
+					reading = r
+				}
+			case <-i.quit:
+				i.readings = nil
+				return
+			}
+		}
+	}()
+	return
+}
+
+// Close down sensor
+func (i *ISL29125) Close() {
+	glog.Info("Closing sensor")
+	if i.quit != nil {
+		i.quit <- true
+	}
+	return
+}