Restore original pull after attachInterrupt

Fixes arduino#253

Author: facchinm

Diff for: cores/arduino/Interrupts.cpp

@@ -53,6 +53,8 @@ void attachInterrupt(PinName interruptNum, voidFuncPtr func, PinStatus mode) {
   attachInterruptParam(interruptNum, (voidFuncPtrParam)func, mode, NULL);
 }
 
+uint8_t _pinMode[NUM_DIGITAL_PINS];
+
 void attachInterruptParam(pin_size_t interruptNum, voidFuncPtrParam func, PinStatus mode, void* param) {
   if (interruptNum >= PINS_COUNT) {
     return;
@@ -77,6 +79,11 @@ void attachInterruptParam(pin_size_t interruptNum, voidFuncPtrParam func, PinSta
     } else {
       pinMode(interruptNum, INPUT);
     }
+  } else {
+    // Restore the original pull
+    if (_pinMode[interruptNum] != OUTPUT) {
+      pinMode(interruptNum, _pinMode[interruptNum]);
+    }
   }
 }
 

Diff for: cores/arduino/wiring_digital.cpp

@@ -49,6 +49,8 @@ void pinMode(PinName pin, PinMode mode)
   }
 }
 
+extern uint8_t _pinMode[];
+
 void pinMode(pin_size_t pin, PinMode mode)
 {
   mbed::DigitalInOut* gpio = digitalPinToGpio(pin);
@@ -57,6 +59,8 @@ void pinMode(pin_size_t pin, PinMode mode)
     digitalPinToGpio(pin) = gpio;
   }
 
+  _pinMode[pin] = mode;
+
   switch (mode) {
     case INPUT:
       gpio->input();