make the framework easier to begin with

driver/linux/gpio/digitalpin.go

@@ -17,24 +17,27 @@ type digitalPin struct {
 	edge      *os.File
 }
 
-func newDigitalPin(n int) (p *digitalPin, err error) {
+func newDigitalPin(n int) (*digitalPin, error) {
 	p = &digitalPin{n: n}
-	err = p.init()
-	return
+	if err := p.init(); err != nil {
+		return nil, err
+	}
+	return p, nil
 }
 
-func (p *digitalPin) init() (err error) {
+func (p *digitalPin) init() error {
+	var err error
 	if p.dir, err = p.directionFile(); err != nil {
-		return
+		return err
 	}
 	if p.val, err = p.valueFile(); err != nil {
-		return
+		return err
 	}
 	if p.activeLow, err = p.activeLowFile(); err != nil {
-		return
+		return err
 	}
 
-	return
+	return nil
 }
 
 func (p *digitalPin) basePath() string {
@@ -57,43 +60,43 @@ func (p *digitalPin) activeLowFile() (*os.File, error) {
 	return p.openFile(path.Join(p.basePath(), "active_low"))
 }
 
-func (p *digitalPin) SetDir(dir gpio.Direction) (err error) {
+func (p *digitalPin) SetDirection(dir gpio.Direction) error {
 	str := "in"
 	if dir == gpio.Out {
 		str = "out"
 	}
-	_, err = p.dir.WriteString(str)
+	_, err := p.dir.WriteString(str)
 	return
 }
 
-func (p *digitalPin) Read() (val int, err error) {
+func (p *digitalPin) Read() (int, error) {
 	buf := make([]byte, 1)
-	if _, err = p.val.Read(buf); err != nil {
-		return
+	if _, err := p.val.Read(buf); err != nil {
+		return 0, err
 	}
-	val = 0
+	var val int
 	if buf[0] == '1' {
 		val = 1
 	}
-	return
+	return val, nil
 }
 
-func (p *digitalPin) Write(val int) (err error) {
+func (p *digitalPin) Write(val int) error {
 	str := "0"
 	if val == gpio.High {
 		str = "1"
 	}
-	_, err = p.val.WriteString(str)
-	return
+	_, err := p.val.WriteString(str)
+	return err
 }
 
-func (p *digitalPin) ActiveLow(b bool) (err error) {
+func (p *digitalPin) ActiveLow(b bool) error {
 	str := "0"
 	if b {
 		str = "1"
 	}
-	_, err = p.activeLow.WriteString(str)
-	return
+	_, err := p.activeLow.WriteString(str)
+	return err
 }
 
 func (p *digitalPin) Close() error {

driver/linux/gpio/gpio.go

@@ -64,38 +64,39 @@ func New(pinMap PinMap) *GPIO {
 	}
 }
 
-func (io *GPIO) init() (err error) {
+func (io *GPIO) init() error {
 	if io.initialized {
-		return
+		return nil
 	}
 
+	var err error
 	if io.exporter, err = os.OpenFile("/sys/class/gpio/export", os.O_WRONLY, os.ModeExclusive); err != nil {
-		return
+		return err
 	}
 	if io.unexporter, err = os.OpenFile("/sys/class/gpio/unexport", os.O_WRONLY, os.ModeExclusive); err != nil {
-		return
+		return err
 	}
 
 	io.initialized = true
 
-	return
+	return nil
 }
 
 func (io *GPIO) lookupKey(key interface{}) (*PinDesc, bool) {
 	return io.pinMap.Lookup(key)
 }
 
-func (io *GPIO) export(n int) (err error) {
-	_, err = io.exporter.WriteString(strconv.Itoa(n))
-	return
+func (io *GPIO) export(n int) error {
+	_, err := io.exporter.WriteString(strconv.Itoa(n))
+	return err
 }
 
-func (io *GPIO) unexport(n int) (err error) {
-	_, err = io.unexporter.WriteString(strconv.Itoa(n))
-	return
+func (io *GPIO) unexport(n int) error {
+	_, err := io.unexporter.WriteString(strconv.Itoa(n))
+	return err
 }
 
-func (io *GPIO) digitalPin(key interface{}) (p *digitalPin, err error) {
+func (io *GPIO) digitalPin(key interface{}) (*digitalPin, error) {
 	pd, found := io.lookupKey(key)
 	if !found {
 		err = fmt.Errorf("gpio: could not find pin matching %q", key)
@@ -104,8 +105,8 @@ func (io *GPIO) digitalPin(key interface{}) (p *digitalPin, err error) {
 
 	n := pd.N
 
-	var ok bool
-	if p, ok = io.initializedPins[n]; ok {
+	p, ok := io.initializedPins[n]
+	if ok {
 		return
 	}
 
@@ -118,18 +119,19 @@ func (io *GPIO) digitalPin(key interface{}) (p *digitalPin, err error) {
 		glog.Infof("gpio: pin %q is not a dedicated GPIO pin. please refer to the system reference manual for more details", key)
 	}
 
-	if err = io.export(n); err != nil {
-		return
+	if err := io.export(n); err != nil {
+		return nil, err
 	}
 
-	if p, err = newDigitalPin(n); err != nil {
+	p, err := newDigitalPin(n)
+	if err != nil {
 		io.unexport(n)
-		return
+		return nil, err
 	}
 
 	io.initializedPins[n] = p
 
-	return
+	return p, nil
 }
 
 func (io *GPIO) DigitalPin(key interface{}) (gpio.DigitalPin, error) {

gpio/gpio.go

@@ -1,5 +1,7 @@
 package gpio
 
+import "github.com/kidoman/embd/host"
+
 type Direction int
 
 const (
@@ -16,14 +18,71 @@ type DigitalPin interface {
 	Write(val int) error
 	Read() (int, error)
 
-	SetDir(dir Direction) error
+	SetDirection(dir Direction) error
 	ActiveLow(b bool) error
 
 	Close() error
 }
 
-type GPIO interface {
+type gpio interface {
 	DigitalPin(key interface{}) (DigitalPin, error)
 
 	Close() error
 }
+
+var instance gpio
+
+func Open() error {
+	desc, err := host.Describe()
+	if err != nil {
+		return err
+	}
+
+	instance = desc.GPIO().(gpio)
+
+	return nil
+}
+
+func Close() error {
+	return instance.Close()
+}
+
+func NewDigitalPin(key interface{}) (DigitalPin, error) {
+	return instance.DigitalPin(key)
+}
+
+func DigitalWrite(key interface{}, val int) error {
+	pin, err := NewDigitalPin(key)
+	if err != nil {
+		return err
+	}
+
+	return pin.Write(val)
+}
+
+func DigitalRead(key interface{}) (int, error) {
+	pin, err := NewDigitalPin(key)
+	if err != nil {
+		return 0, err
+	}
+
+	return pin.Read()
+}
+
+func SetDirection(key interface{}, dir Direction) error {
+	pin, err := NewDigitalPin(key)
+	if err != nil {
+		return err
+	}
+
+	return pin.SetDirection(dir)
+}
+
+func ActiveLow(key interface{}, b bool) error {
+	pin, err := NewDigitalPin(key)
+	if err != nil {
+		return err
+	}
+
+	return pin.ActiveLow(b)
+}

hal.go

@@ -1,35 +0,0 @@
-package embd
-
-import (
-	"github.com/kidoman/embd/gpio"
-	"github.com/kidoman/embd/host"
-	"github.com/kidoman/embd/i2c"
-)
-
-const (
-	In  = gpio.In
-	Out = gpio.Out
-)
-
-const (
-	Low  = gpio.Low
-	High = gpio.High
-)
-
-func NewGPIO() (gpio.GPIO, error) {
-	desc, err := host.Describe()
-	if err != nil {
-		return nil, err
-	}
-
-	return desc.GPIO(), nil
-}
-
-func NewI2C() (i2c.I2C, error) {
-	desc, err := host.Describe()
-	if err != nil {
-		return nil, err
-	}
-
-	return desc.I2C(), nil
-}

host/bbb/descriptor.go

@@ -3,7 +3,6 @@ package bbb
 import (
 	lgpio "github.com/kidoman/embd/driver/linux/gpio"
 	li2c "github.com/kidoman/embd/driver/linux/i2c"
-	"github.com/kidoman/embd/gpio"
 	"github.com/kidoman/embd/host"
 )
 
@@ -13,7 +12,7 @@ func init() {
 
 func describer(rev int) *host.Descriptor {
 	return &host.Descriptor{
-		GPIO: func() gpio.GPIO {
+		GPIO: func() interface{} {
 			return lgpio.New(pins)
 		},
 		I2C: li2c.New,

host/descriptor.go

@@ -1,15 +1,10 @@
 package host
 
-import (
-	"errors"
-
-	"github.com/kidoman/embd/gpio"
-	"github.com/kidoman/embd/i2c"
-)
+import "errors"
 
 type Descriptor struct {
-	GPIO func() gpio.GPIO
-	I2C  func() i2c.I2C
+	GPIO func() interface{}
+	I2C  func() interface{}
 }
 
 type Describer func(rev int) *Descriptor

host/rpi/descriptor.go

@@ -3,8 +3,7 @@ package rpi
 import (
 	lgpio "github.com/kidoman/embd/driver/linux/gpio"
 	li2c "github.com/kidoman/embd/driver/linux/i2c"
-	"github.com/kidoman/embd/gpio"
-	"github.com/kidoman/embd/i2c"
+	"github.com/kidoman/embd/host"
 )
 
 func init() {
@@ -18,7 +17,7 @@ func describer(rev int) *host.Descriptor {
 	}
 
 	return &host.Descriptor{
-		GPIO: func() gpio.GPIO {
+		GPIO: func() interface{} {
 			return lgpio.New(pins)
 		},
 		I2C: li2c.New,

i2c/i2c.go

@@ -1,6 +1,8 @@
 // Package i2c enables gophers i2c speaking ability.
 package i2c
 
+import "github.com/kidoman/embd/host"
+
 type Bus interface {
 	// ReadByte reads a byte from the given address.
 	ReadByte(addr byte) (value byte, err error)
@@ -29,3 +31,24 @@ type I2C interface {
 
 	Close() error
 }
+
+var instance I2C
+
+func Open() error {
+	desc, err := host.Describe()
+	if err != nil {
+		return err
+	}
+
+	instance = desc.I2C().(I2C)
+
+	return nil
+}
+
+func Close() error {
+	return instance.Close()
+}
+
+func NewBus(l byte) Bus {
+	return instance.Bus(l)
+}

samples/.gitignore

@@ -3,13 +3,14 @@ bmp085
 bmp180
 gpio
 gpiodetect
+gpiodirect
+gpioshort
 l3gd20
 lsm303
 mcp4725
 pca9685
 servo
 servoblaster
-spi
 tmp006
 us020
 watersensor

samples/Makefile

@@ -0,0 +1,2 @@
+build: *.go
+	echo $^ | xargs -n1 -I {} go build {}

samples/bh1750fvi.go

@@ -3,17 +3,18 @@ package main
 import (
 	"log"
 	"time"
-	"github.com/kidoman/embd"
+
+	"github.com/kidoman/embd/i2c"
 	"github.com/kidoman/embd/sensor/bh1750fvi"
 )
 
 func main() {
-	i2c, err := embd.NewI2C()
-	if err != nil {
+	if err := i2c.Open(); err != nil {
 		panic(err)
 	}
+	defer i2c.Close()
 
-	bus := i2c.Bus(1)
+	bus := i2c.NewBus(1)
 
 	sensor := bh1750fvi.New(bh1750fvi.High, bus)
 	defer sensor.Close()

samples/bmp085.go

@@ -3,17 +3,18 @@ package main
 import (
 	"log"
 	"time"
-	"github.com/kidoman/embd"
+
+	"github.com/kidoman/embd/i2c"
 	"github.com/kidoman/embd/sensor/bmp085"
 )
 
 func main() {
-	i2c, err := embd.NewI2C()
-	if err != nil {
+	if err := i2c.Open(); err != nil {
 		panic(err)
 	}
+	defer i2c.Close()
 
-	bus := i2c.Bus(1)
+	bus := i2c.NewBus(1)
 
 	baro := bmp085.New(bus)
 	defer baro.Close()

samples/bmp180.go

@@ -3,17 +3,18 @@ package main
 import (
 	"log"
 	"time"
-	"github.com/kidoman/embd"
+
+	"github.com/kidoman/embd/i2c"
 	"github.com/kidoman/embd/sensor/bmp180"
 )
 
 func main() {
-	i2c, err := embd.NewI2C()
-	if err != nil {
+	if err := i2c.Open(); err != nil {
 		panic(err)
 	}
+	defer i2c.Close()
 
-	bus := i2c.Bus(1)
+	bus := i2c.NewBus(1)
 
 	baro := bmp180.New(bus)
 	defer baro.Close()

samples/gpio.go

@@ -3,31 +3,30 @@ package main
 import (
 	"time"
 
-	"github.com/kidoman/embd"
+	"github.com/kidoman/embd/gpio"
 )
 
 func main() {
-	gpio, err := embd.NewGPIO()
-	if err != nil {
+	if err := gpio.Open(); err != nil {
 		panic(err)
 	}
 	defer gpio.Close()
 
-	led, err := gpio.DigitalPin(10)
+	led, err := gpio.NewDigitalPin(10)
 	if err != nil {
 		panic(err)
 	}
 
-	if err := led.SetDir(embd.Out); err != nil {
+	if err := led.SetDirection(gpio.Out); err != nil {
 		panic(err)
 	}
-	if err := led.Write(embd.High); err != nil {
+	if err := led.Write(gpio.High); err != nil {
 		panic(err)
 	}
 
 	time.Sleep(1 * time.Second)
 
-	if err := led.SetDir(embd.In); err != nil {
+	if err := led.SetDirection(gpio.In); err != nil {
 		panic(err)
 	}
 }

samples/gpiodetect.go

@@ -3,7 +3,7 @@ package main
 import (
 	"time"
 
-	"github.com/kidoman/embd"
+	"github.com/kidoman/embd/gpio"
 	"github.com/kidoman/embd/host"
 )
 
@@ -24,28 +24,27 @@ func main() {
 		panic("host not supported (yet :P)")
 	}
 
-	gpio, err := embd.NewGPIO()
-	if err != nil {
+	if err := gpio.Open(); err != nil {
 		panic(err)
 	}
 	defer gpio.Close()
 
-	led, err := gpio.DigitalPin(pinNo)
+	led, err := gpio.NewDigitalPin(pinNo)
 	if err != nil {
 		panic(err)
 	}
 	defer led.Close()
 
-	if err := led.SetDir(embd.Out); err != nil {
+	if err := led.SetDirection(gpio.Out); err != nil {
 		panic(err)
 	}
-	if err := led.Write(embd.High); err != nil {
+	if err := led.Write(gpio.High); err != nil {
 		panic(err)
 	}
 
 	time.Sleep(1 * time.Second)
 
-	if err := led.SetDir(embd.In); err != nil {
+	if err := led.SetDirection(gpio.In); err != nil {
 		panic(err)
 	}
 }

samples/gpiodirect.go

@@ -0,0 +1,27 @@
+package main
+
+import (
+	"time"
+
+	"github.com/kidoman/embd/gpio"
+)
+
+func main() {
+	if err := gpio.Open(); err != nil {
+		panic(err)
+	}
+	defer gpio.Close()
+
+	if err := gpio.SetDirection(10, gpio.Out); err != nil {
+		panic(err)
+	}
+	if err := gpio.DigitalWrite(10, gpio.High); err != nil {
+		panic(err)
+	}
+
+	time.Sleep(1 * time.Second)
+
+	if err := gpio.SetDirection(10, gpio.In); err != nil {
+		panic(err)
+	}
+}

samples/gpioshort.go

@@ -0,0 +1,11 @@
+package main
+
+import "github.com/kidoman/embd/gpio"
+
+func main() {
+	gpio.Open()
+	defer gpio.Close()
+
+	gpio.SetDirection(10, gpio.Out)
+	gpio.DigitalWrite(10, gpio.High)
+}

samples/l3gd20.go

@@ -5,17 +5,18 @@ import (
 	"os"
 	"os/signal"
 	"time"
-	"github.com/kidoman/embd"
+
+	"github.com/kidoman/embd/i2c"
 	"github.com/kidoman/embd/sensor/l3gd20"
 )
 
 func main() {
-	i2c, err := embd.NewI2C()
-	if err != nil {
+	if err := i2c.Open(); err != nil {
 		panic(err)
 	}
+	defer i2c.Close()
 
-	bus := i2c.Bus(1)
+	bus := i2c.NewBus(1)
 
 	gyro := l3gd20.New(bus, l3gd20.R250DPS)
 	gyro.Debug = true

samples/lsm303.go

@@ -4,18 +4,17 @@ import (
 	"log"
 	"time"
 
-	"github.com/kidoman/embd"
+	"github.com/kidoman/embd/i2c"
 	"github.com/kidoman/embd/sensor/lsm303"
 )
 
 func main() {
-	i2c, err := embd.NewI2C()
-	if err != nil {
+	if err := i2c.Open(); err != nil {
 		panic(err)
 	}
 	defer i2c.Close()
 
-	bus := i2c.Bus(1)
+	bus := i2c.NewBus(1)
 
 	mems := lsm303.New(bus)
 	defer mems.Close()

samples/mcp4725.go

@@ -6,17 +6,17 @@ import (
 	"os"
 	"os/signal"
 
-	"github.com/kidoman/embd"
 	"github.com/kidoman/embd/controller/mcp4725"
+	"github.com/kidoman/embd/i2c"
 )
 
 func main() {
-	i2c, err := embd.NewI2C()
-	if err != nil {
+	if err := i2c.Open(); err != nil {
 		panic(err)
 	}
+	defer i2c.Close()
 
-	bus := i2c.Bus(1)
+	bus := i2c.NewBus(1)
 
 	dac := mcp4725.New(bus, 0x62)
 	defer dac.Close()

samples/pca9685.go

@@ -6,17 +6,17 @@ import (
 	"os/signal"
 	"time"
 
-	"github.com/kidoman/embd"
 	"github.com/kidoman/embd/controller/pca9685"
+	"github.com/kidoman/embd/i2c"
 )
 
 func main() {
-	i2c, err := embd.NewI2C()
-	if err != nil {
+	if err := i2c.Open(); err != nil {
 		panic(err)
 	}
+	defer i2c.Close()
 
-	bus := i2c.Bus(1)
+	bus := i2c.NewBus(1)
 
 	pca9685 := pca9685.New(bus, 0x41)
 	pca9685.Freq = 1000

samples/servo.go

@@ -5,18 +5,18 @@ import (
 	"os/signal"
 	"time"
 
-	"github.com/kidoman/embd"
 	"github.com/kidoman/embd/controller/pca9685"
+	"github.com/kidoman/embd/i2c"
 	"github.com/kidoman/embd/motion/servo"
 )
 
 func main() {
-	i2c, err := embd.NewI2C()
-	if err != nil {
+	if err := i2c.Open(); err != nil {
 		panic(err)
 	}
+	defer i2c.Close()
 
-	bus := i2c.Bus(1)
+	bus := i2c.NewBus(1)
 
 	pwm := pca9685.New(bus, 0x41)
 	pwm.Freq = 50

samples/spi.go

@@ -1,18 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"github.com/kidoman/embd/spi"
-)
-
-func main() {
-	var rx_data uint8
-
-	fmt.Println("Hello")
-
-	bus, _ := spi.NewSpiBus()
-
-	rx_data, _ = bus.TransferAndRecieveByteData(8`	)
-
-	fmt.Printf("Received %v \n", rx_data)
-}

samples/tmp006.go

@@ -5,17 +5,17 @@ import (
 	"os"
 	"os/signal"
 
-	"github.com/kidoman/embd"
+	"github.com/kidoman/embd/i2c"
 	"github.com/kidoman/embd/sensor/tmp006"
 )
 
 func main() {
-	i2c, err := embd.NewI2C()
-	if err != nil {
+	if err := i2c.Open(); err != nil {
 		panic(err)
 	}
+	defer i2c.Close()
 
-	bus := i2c.Bus(1)
+	bus := i2c.NewBus(1)
 
 	sensor := tmp006.New(bus, 0x40)
 	if status, err := sensor.Present(); err != nil || !status {

samples/us020.go

@@ -4,22 +4,21 @@ import (
 	"log"
 	"time"
 
-	"github.com/kidoman/embd"
+	"github.com/kidoman/embd/gpio"
 	"github.com/kidoman/embd/sensor/us020"
 )
 
 func main() {
-	gpio, err := embd.NewGPIO()
-	if err != nil {
+	if err := gpio.Open(); err != nil {
 		panic(err)
 	}
 	defer gpio.Close()
 
-	echoPin, err := gpio.DigitalPin(10)
+	echoPin, err := gpio.NewDigitalPin(10)
 	if err != nil {
 		panic(err)
 	}
-	triggerPin, err := gpio.DigitalPin(9)
+	triggerPin, err := gpio.NewDigitalPin(9)
 	if err != nil {
 		panic(err)
 	}

sensor/us020/us020.go

@@ -6,7 +6,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/kidoman/embd"
 	"github.com/kidoman/embd/gpio"
 )
 
@@ -59,8 +58,8 @@ func (d *US020) setup() (err error) {
 	d.mu.Lock()
 	defer d.mu.Unlock()
 
-	d.TriggerPin.SetDir(embd.Out)
-	d.EchoPin.SetDir(embd.In)
+	d.TriggerPin.SetDirection(gpio.Out)
+	d.EchoPin.SetDirection(gpio.In)
 
 	if d.Thermometer == nil {
 		d.Thermometer = NullThermometer
@@ -107,7 +106,7 @@ func (d *US020) Distance() (distance float64, err error) {
 			return 0, err
 		}
 
-		if v != embd.Low {
+		if v != gpio.Low {
 			break
 		}
 	}
@@ -125,7 +124,7 @@ func (d *US020) Distance() (distance float64, err error) {
 			return 0, err
 		}
 
-		if v != embd.High {
+		if v != gpio.High {
 			break
 		}
 	}
@@ -140,5 +139,5 @@ func (d *US020) Distance() (distance float64, err error) {
 
 // Close.
 func (d *US020) Close() {
-	d.EchoPin.SetDir(embd.Out)
+	d.EchoPin.SetDirection(gpio.Out)
 }