diff --git a/hardware/sam/cores/sam/Arduino.h b/hardware/sam/cores/sam/Arduino.h
index c65d7bfa5..05caf2603 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"
@@ -53,15 +53,13 @@ extern void loop( void ) ;
 //
 // These perform slightly better as macros compared to inline functions
 //
-#define digitalPinToPort( ulPin )    ( g_APinDescription[ulPin].pPort )
-#define digitalPinToBitMask( ulPin ) ( g_APinDescription[ulPin].dwPin )
-/*
+#define digitalPinToPort( ulPin )    ( g_APinDescription[ulPin]->pPort->PIO_PDSR )
+#define digitalPinToBitMask( ulPin ) ( g_APinDescription[ulPin]->dwPin )
 #define digitalPinToTimer( P )   (  )
 #define analogInPinToBit( P )    ( P )
 #define portOutputRegister( P )  (  )
 #define portInputRegister( P )   (  )
 #define portModeRegister( P )    (  )
-*/
 
 //#define NOT_A_PIN 0  // defined in pio.h/EPioType
 #define NOT_A_PORT           0
@@ -85,7 +83,7 @@ typedef enum _EExt_Interrupts
 typedef void (*voidFuncPtr)( void ) ;
 
 /* Define attribute */
-#if defined   ( __CC_ARM   ) /* Keil �Vision 4 */
+#if defined   ( __CC_ARM   ) /* Keil uVision 4 */
     #define WEAK (__attribute__ ((weak)))
 #elif defined ( __ICCARM__ ) /* IAR Ewarm 5.41+ */
     #define WEAK __weak
@@ -149,6 +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/UARTClass.cpp b/hardware/sam/cores/sam/UARTClass.cpp
index 6bd79c022..76a60d3b3 100644
--- a/hardware/sam/cores/sam/UARTClass.cpp
+++ b/hardware/sam/cores/sam/UARTClass.cpp
@@ -120,10 +120,8 @@ void UARTClass::flush( void )
 void UARTClass::write( const uint8_t uc_data )
 {
   /* Check if the transmitter is ready */
-  if ( (_pUart->UART_SR & UART_SR_TXRDY) != UART_SR_TXRDY )
-  {
-      return ;
-  }
+  while ( (_pUart->UART_SR & UART_SR_TXRDY) != UART_SR_TXRDY )
+    ;
 
   /* Send character */
   _pUart->UART_THR = uc_data ;
diff --git a/hardware/sam/cores/sam/wiring_pulse.c.disabled b/hardware/sam/cores/sam/wiring_pulse.cpp
similarity index 71%
rename from hardware/sam/cores/sam/wiring_pulse.c.disabled
rename to hardware/sam/cores/sam/wiring_pulse.cpp
index 3e91c0432..40f1261ae 100644
--- a/hardware/sam/cores/sam/wiring_pulse.c.disabled
+++ b/hardware/sam/cores/sam/wiring_pulse.cpp
@@ -16,47 +16,46 @@
   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 ulPin, uint32_t ulState, uint32_t ulTimeout )
+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.
-	uint8_t bit = digitalPinToBitMask(pin);
-	uint8_t port = digitalPinToPort(pin);
-	uint8_t stateMask = (state ? bit : 0);
-	unsigned long width = 0; // keep initialization out of time critical area
+	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 16 clock cycles per iteration.
-	unsigned long numloops = 0;
-	unsigned long maxloops = microsecondsToClockCycles(timeout) / 16;
+	// 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 ((*portInputRegister(port) & bit) == stateMask)
+	while (PIO_Get(p.pPort, PIO_INPUT, p.ulPin) == state)
 		if (numloops++ == maxloops)
 			return 0;
 	
 	// wait for the pulse to start
-	while ((*portInputRegister(port) & bit) != stateMask)
+	while (PIO_Get(p.pPort, PIO_INPUT, p.ulPin) != state)
 		if (numloops++ == maxloops)
 			return 0;
 	
 	// wait for the pulse to stop
-	while ((*portInputRegister(port) & bit) == stateMask) {
+	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 20 clock cycles long and have about 16 clocks between the edge
+	// 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 * 21 + 16); 
+	return clockCyclesToMicroseconds(width * 22 + 16);
 }