Use physical PIN number in blinker example.

The behavior of the test is not changed, now it hides BCM bin number and
used physical PIN number.

Author: Aleksei Fedotov

examples/blinker/blinker.go

@@ -17,11 +17,6 @@ import (
 	"time"
 )
 
-var (
-	// Use mcu pin 10, corresponds to physical pin 19 on the pi
-	pin = rpio.Pin(10)
-)
-
 func main() {
 	// Open and map memory to access gpio, check for errors
 	if err := rpio.Open(); err != nil {
@@ -32,6 +27,13 @@ func main() {
 	// Unmap gpio memory when done
 	defer rpio.Close()
 
+	// Use physical pin 19, mappings to GPIO numers are done internally
+	pin, err := rpio.GetBoardPin(19)
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+
 	// Set pin to output mode
 	pin.Output()