Fix interrupt number conversion

Add Arduino Due experimental support feature

Author: HyodaKazuaki

SUPPORTED.md

@@ -33,4 +33,4 @@ If you have successfully used this library with an unconfirmed board, please let
 | Arduino Industrial 101 | △ |
 | Linino One | △ |
 | Arduino Uno WiFi | △ |
-| Arduino Due | ╳ |
+| Arduino Due | △ |

library.properties

@@ -6,4 +6,4 @@ sentence=A library that makes control Parallax FeedBack360 servo easy.
 paragraph=You can control servo to degree of rotation what you want with this library. Of course, you can read servo's degree of rotation.
 category=Device Control
 url=https://github.com/HyodaKazuaki/FeedBack360-Servo-Control-Library-4-Arduino
-architectures=avr
+architectures=avr,sam

src/FeedBackServo.cpp

@@ -23,8 +23,8 @@ FeedBackServo::FeedBackServo(byte _feedbackPinNumber = 2)
     pinCheck(_feedbackPinNumber);
     feedbackPinNumber = _feedbackPinNumber;
 
-    // convert feedback pin number for use on attachInterrupt function
-    byte internalPinNumber = convertFeedbackPin();
+    // convert feedback pin number to interrupt number for use on attachInterrupt function
+    uint8_t internalPinNumber = digitalPinToInterrupt(feedbackPinNumber);
 
     attachInterrupt(internalPinNumber, feedback, CHANGE);
 }
@@ -79,49 +79,6 @@ void FeedBackServo::pinCheck(byte _feedbackPinNumber)
     #endif
 }
 
-byte FeedBackServo::convertFeedbackPin()
-{
-    byte internalPinNumber;
-    #ifdef ARDUINO_AVR_UNO
-    switch (feedbackPinNumber)
-    {
-    case 2:
-        internalPinNumber = 0;
-        break;
-    case 3:
-        internalPinNumber = 1;
-        break;
-    default:
-        internalPinNumber = 0;
-        break;
-    }
-    #endif
-    #ifdef ARDUINO_AVR_LEONARDO
-    switch (feedbackPinNumber)
-    {
-    case 0:
-        internalPinNumber = 2;
-        break;
-    case 1:
-        internalPinNumber = 3;
-        break;
-    case 2:
-        internalPinNumber = 1;
-        break;
-    case 3:
-        internalPinNumber = 0;
-        break;
-    case 7:
-        internalPinNumber = 4;
-        break;
-    default:
-        internalPinNumber = 0;
-        break;
-    }
-    #endif
-    return internalPinNumber;
-}
-
 static void FeedBackServo::feedback() {
     if(digitalRead(feedbackPinNumber)) {
         rise = micros();