Add support for isl29125 RGB light sensor

samples/isl29125.go

@@ -7,9 +7,8 @@ import (
 	"time"
 
 	"github.com/kidoman/embd"
-	"github.com/kidoman/embd/sensor/isl29125"
-
 	_ "github.com/kidoman/embd/host/all"
+	"github.com/kidoman/embd/sensor/isl29125"
 )
 
 func main() {
@@ -23,6 +22,7 @@ func main() {
 
 	isl := isl29125.New(isl29125.DefaultConfig, bus)
 	defer isl.Close()
+	isl.Init()
 
 	for {
 		r, err := isl.Reading()

sensor/isl29125/isl29125.go

@@ -5,12 +5,15 @@ package isl29125
 /*
 
    TODO:
-       - improve constructor
-       - add support for config register 2 and 3
-       - add support for lux calculation
+       - add support for the following:
+           - config register 2 and 3
+           - lux calculation
+           - powerdown / power up
+           - interupt config / monitor
 */
 
 import (
+	"fmt"
 	"time"
 
 	"github.com/golang/glog"
@@ -18,13 +21,7 @@ import (
 )
 
 const (
-	sensorI2cAddr = 0x44
-
 	pollDelay = 250
-
-	deviceRegisterAddr = 0x00
-	conf1RegisterAddr  = 0x01
-	flagRegisterAdr    = 0x08
 )
 
 const (
@@ -43,6 +40,12 @@ const (
 	LuxRange10k = 0x08
 )
 
+const (
+	IRAdjustLow  = 0x00
+	IRAdjustMed  = 0x20
+	IRAdjustHigh = 0x3f
+)
+
 const (
 	Resolution16Bit = 0x00
 	Resolution12Bit = 0x10
@@ -54,6 +57,11 @@ const (
 )
 
 const (
+	RegisterDeviceID  = 0x00
+	RegisterConfig1   = 0x01
+	RegisterConfig2   = 0x02
+	RegisterConfig3   = 0x03
+	RegisterFlags     = 0x08
 	RegisterGreenLow  = 0x09
 	RegisterGreenHigh = 0x0a
 	RegisterRedLow    = 0x0b
@@ -63,6 +71,7 @@ const (
 )
 
 const (
+	FlagReady               = 0x00
 	FlagInterrupt           = 0x01
 	FlagConversion          = 0x02
 	FlagPowerDownOrBrownOut = 0x04
@@ -72,11 +81,17 @@ const (
 )
 
 const (
-	DefaultConfig = ModePowerDown | LuxRange375 | Resolution16Bit | SyncStartOnWrite
+	DefaultConfig = ModeRGB | LuxRange375 | Resolution16Bit | SyncStartOnWrite
 )
 
 const (
-	DeviceID = 0x7d
+	SensorAddr = 0x44
+	DeviceID   = 0x7d
+)
+
+const (
+	CmdGetStatus = 0x08
+	CmdReset     = 0x46
 )
 
 // Reading represents a single reading from an RGB light sensor
@@ -97,30 +112,82 @@ type ISL29125 struct {
 	readings chan *Reading
 	quit     chan bool
 
-	mode       int
-	luxRange   int
-	resolution int
-	syncStart  int
+	mode uint8
 }
 
 // New returns an ISL29125 for a given config
-func New(config int, bus embd.I2CBus) *ISL29125 {
+func New(config uint8, bus embd.I2CBus) *ISL29125 {
 	glog.Info("Creating new ISL29125")
-	return &ISL29125{Bus: bus, Poll: pollDelay}
+	return &ISL29125{Bus: bus, Poll: pollDelay, mode: config}
+}
+
+func (i *ISL29125) Init() error {
+
+	// verify that i2c device is reachable on specified bus and that it reports back the correct ID
+	id, err := i.Bus.ReadByteFromReg(SensorAddr, RegisterDeviceID)
+	if err != nil {
+		return err
+	}
+	if DeviceID != id {
+		return fmt.Errorf("Invalid device id. Expected [%x] but device reports [%x]", DeviceID, id)
+	}
+
+	// power down device ( don't know current state; assume it's running )
+	err = i.Bus.WriteByteToReg(SensorAddr, RegisterConfig1, ModePowerDown)
+	if err != nil {
+		return err
+	}
+	time.Sleep(100 * time.Millisecond)
+
+	// reset device
+	err = i.Bus.WriteByteToReg(SensorAddr, DeviceID, CmdReset)
+	if err != nil {
+		return err
+	}
+	time.Sleep(100 * time.Millisecond)
+
+	// verify status after reset is ready
+	status, err := i.Bus.ReadByteFromReg(SensorAddr, CmdGetStatus)
+	if err != nil {
+		return err
+	}
+	if status != FlagReady {
+		return fmt.Errorf("Invalid device status. Expected [%x] but device reports [%x]", FlagReady, status)
+	}
+
+	// set config 1 to user specified mode
+	err = i.Bus.WriteByteToReg(SensorAddr, RegisterConfig1, i.mode)
+	if err != nil {
+		return err
+	}
+	// set config 2 to fixed value
+	err = i.Bus.WriteByteToReg(SensorAddr, RegisterConfig2, IRAdjustHigh)
+	if err != nil {
+		return err
+	}
+
+	// set config 3 to fixed value
+	err = i.Bus.WriteByteToReg(SensorAddr, RegisterConfig3, 0x0)
+	if err != nil {
+		return err
+	}
+
+	return nil
+
 }
 
 func (i *ISL29125) getReading() (*Reading, error) {
 
 	glog.Info("Getting reading")
-	red, err := i.Bus.ReadWordFromReg(sensorI2cAddr, RegisterRedLow)
+	red, err := i.Bus.ReadWordFromReg(SensorAddr, RegisterRedLow)
 	if err != nil {
 		return nil, err
 	}
-	green, err := i.Bus.ReadWordFromReg(sensorI2cAddr, RegisterGreenLow)
+	green, err := i.Bus.ReadWordFromReg(SensorAddr, RegisterGreenLow)
 	if err != nil {
 		return nil, err
 	}
-	blue, err := i.Bus.ReadWordFromReg(sensorI2cAddr, RegisterBlueLow)
+	blue, err := i.Bus.ReadWordFromReg(SensorAddr, RegisterBlueLow)
 	if err != nil {
 		return nil, err
 	}