make the framework easier to begin with

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)
+}