diff --git a/hardware/sam/cores/sam/Arduino.h b/hardware/sam/cores/sam/Arduino.h
index eecd19467..955b12553 100644
--- a/hardware/sam/cores/sam/Arduino.h
+++ b/hardware/sam/cores/sam/Arduino.h
@@ -35,7 +35,7 @@ extern "C"{
 
 #define clockCyclesPerMicrosecond() ( SystemCoreClock / 1000000L )
 #define clockCyclesToMicroseconds(a) ( ((a) * 1000L) / (SystemCoreClock / 1000L) )
-#define microsecondsToClockCycles(a) ( ((a) * (SystemCoreClock / 1000L)) / 1000L )
+#define microsecondsToClockCycles(a) ( (a) * (SystemCoreClock / 1000000L) )
 
 
 #include "wiring.h"
@@ -53,7 +53,7 @@ extern void loop( void ) ;
 //
 // These perform slightly better as macros compared to inline functions
 //
-#define digitalPinToPort( ulPin )    ( g_APinDescription[ulPin]->pPort )
+#define digitalPinToPort( ulPin )    ( g_APinDescription[ulPin]->pPort->PIO_PDSR )
 #define digitalPinToBitMask( ulPin ) ( g_APinDescription[ulPin]->dwPin )
 #define digitalPinToTimer( P )   (  )
 #define analogInPinToBit( P )    ( P )
@@ -83,7 +83,7 @@ typedef enum _EExt_Interrupts
 typedef void (*voidFuncPtr)( void ) ;
 
 /* Define attribute */
-#if defined   ( __CC_ARM   ) /* Keil µVision 4 */
+#if defined   ( __CC_ARM   ) /* Keil Vision 4 */
     #define WEAK (__attribute__ ((weak)))
 #elif defined ( __ICCARM__ ) /* IAR Ewarm 5.41+ */
     #define WEAK __weak
@@ -147,6 +147,7 @@ extern const PinDescription g_APinDescription[] ;
 #include "Tone.h"
 #include "WMath.h"
 #include "HardwareSerial.h"
+#include "wiring_pulse.h"
 #endif // __cplusplus
 
 #endif // Arduino_h
diff --git a/hardware/sam/cores/sam/wiring_pulse.cpp b/hardware/sam/cores/sam/wiring_pulse.cpp
new file mode 100644
index 000000000..40f1261ae
--- /dev/null
+++ b/hardware/sam/cores/sam/wiring_pulse.cpp
@@ -0,0 +1,61 @@
+/*
+  Copyright (c) 2011 Arduino.  All right reserved.
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
+  See the GNU Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#include "Arduino.h"
+#include "wiring_private.h"
+
+/* Measures the length (in microseconds) of a pulse on the pin; state is HIGH
+ * or LOW, the type of pulse to measure.  Works on pulses from 2-3 microseconds
+ * to 3 minutes in length, but must be called at least a few dozen microseconds
+ * before the start of the pulse. */
+extern uint32_t pulseIn( uint32_t pin, uint32_t state, uint32_t timeout )
+{
+	// cache the port and bit of the pin in order to speed up the
+	// pulse width measuring loop and achieve finer resolution.  calling
+	// digitalRead() instead yields much coarser resolution.
+	PinDescription p = g_APinDescription[pin];
+	uint32_t width = 0; // keep initialization out of time critical area
+	
+	// convert the timeout from microseconds to a number of times through
+	// the initial loop; it takes 22 clock cycles per iteration.
+	uint32_t numloops = 0;
+	uint32_t maxloops = microsecondsToClockCycles(timeout) / 22;
+	
+	// wait for any previous pulse to end
+	while (PIO_Get(p.pPort, PIO_INPUT, p.ulPin) == state)
+		if (numloops++ == maxloops)
+			return 0;
+	
+	// wait for the pulse to start
+	while (PIO_Get(p.pPort, PIO_INPUT, p.ulPin) != state)
+		if (numloops++ == maxloops)
+			return 0;
+	
+	// wait for the pulse to stop
+	while (PIO_Get(p.pPort, PIO_INPUT, p.ulPin) == state) {
+		if (numloops++ == maxloops)
+			return 0;
+		width++;
+	}
+
+	// convert the reading to microseconds. The loop has been determined
+	// to be 22 clock cycles long and have about 16 clocks between the edge
+	// and the start of the loop. There will be some error introduced by
+	// the interrupt handlers.
+	return clockCyclesToMicroseconds(width * 22 + 16);
+}