make the framework easier to begin with

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)
+}