diff --git a/build/shared/revisions.txt b/build/shared/revisions.txt
index 2fc67e11e..d9e9b863f 100644
--- a/build/shared/revisions.txt
+++ b/build/shared/revisions.txt
@@ -20,6 +20,8 @@ ARDUINO 1.5.3 BETA
 
 [libraries]
 * sam: Added CAN library (still in early stage of development) (Palliser)
+* sam: Bugfix SPI library: begin() after end() now works (stimmer)
+* sam: Bugfix SPI library: incorrent pin configuration in non-extended mode.
 
 [firmwares]
 * Arduino Due: fixed USB2Serial garbage at startup (https://github.com/arduino/Arduino/pull/1267)
diff --git a/hardware/arduino/avr/cores/arduino/WString.cpp b/hardware/arduino/avr/cores/arduino/WString.cpp
index 8c85cc592..48c30df77 100644
--- a/hardware/arduino/avr/cores/arduino/WString.cpp
+++ b/hardware/arduino/avr/cores/arduino/WString.cpp
@@ -325,14 +325,14 @@ unsigned char String::concat(unsigned long num)
 unsigned char String::concat(float num)
 {
 	char buf[20];
-	char* string = dtostrf(num, 8, 6, buf);
+	char* string = dtostrf(num, 8, 2, buf);
 	return concat(string, strlen(string));
 }
 
 unsigned char String::concat(double num)
 {
 	char buf[20];
-	char* string = dtostrf(num, 8, 6, buf);
+	char* string = dtostrf(num, 8, 2, buf);
 	return concat(string, strlen(string));
 }
 
diff --git a/hardware/arduino/avr/cores/arduino/WString.h b/hardware/arduino/avr/cores/arduino/WString.h
index 44a841930..b3b9f1427 100644
--- a/hardware/arduino/avr/cores/arduino/WString.h
+++ b/hardware/arduino/avr/cores/arduino/WString.h
@@ -69,8 +69,8 @@ public:
 	explicit String(unsigned int, unsigned char base=10);
 	explicit String(long, unsigned char base=10);
 	explicit String(unsigned long, unsigned char base=10);
-	explicit String(float, int decimalPlaces=6);
-	explicit String(double, int decimalPlaces=6);
+	explicit String(float, int decimalPlaces=2);
+	explicit String(double, int decimalPlaces=2);
 	~String(void);
 
 	// memory management
diff --git a/hardware/arduino/avr/cores/robot/WString.cpp b/hardware/arduino/avr/cores/robot/WString.cpp
index 8c85cc592..48c30df77 100644
--- a/hardware/arduino/avr/cores/robot/WString.cpp
+++ b/hardware/arduino/avr/cores/robot/WString.cpp
@@ -325,14 +325,14 @@ unsigned char String::concat(unsigned long num)
 unsigned char String::concat(float num)
 {
 	char buf[20];
-	char* string = dtostrf(num, 8, 6, buf);
+	char* string = dtostrf(num, 8, 2, buf);
 	return concat(string, strlen(string));
 }
 
 unsigned char String::concat(double num)
 {
 	char buf[20];
-	char* string = dtostrf(num, 8, 6, buf);
+	char* string = dtostrf(num, 8, 2, buf);
 	return concat(string, strlen(string));
 }
 
diff --git a/hardware/arduino/avr/cores/robot/WString.h b/hardware/arduino/avr/cores/robot/WString.h
index 4b9e64e0b..0404f767a 100644
--- a/hardware/arduino/avr/cores/robot/WString.h
+++ b/hardware/arduino/avr/cores/robot/WString.h
@@ -69,8 +69,8 @@ public:
 	explicit String(unsigned int, unsigned char base=10);
 	explicit String(long, unsigned char base=10);
 	explicit String(unsigned long, unsigned char base=10);
-	explicit String(float, int decimalPlaces=6);
-	explicit String(double, int decimalPlaces=6);
+	explicit String(float, int decimalPlaces=2);
+	explicit String(double, int decimalPlaces=2);
 	~String(void);
 
 	// memory management
diff --git a/hardware/arduino/sam/cores/arduino/WString.cpp b/hardware/arduino/sam/cores/arduino/WString.cpp
index de1a2f1b2..d6b344c2a 100644
--- a/hardware/arduino/sam/cores/arduino/WString.cpp
+++ b/hardware/arduino/sam/cores/arduino/WString.cpp
@@ -326,14 +326,14 @@ unsigned char String::concat(unsigned long num)
 unsigned char String::concat(float num)
 {
 	char buf[20];
-	char* string = dtostrf(num, 8, 6, buf);
+	char* string = dtostrf(num, 8, 2, buf);
 	return concat(string, strlen(string));
 }
 
 unsigned char String::concat(double num)
 {
 	char buf[20];
-	char* string = dtostrf(num, 8, 6, buf);
+	char* string = dtostrf(num, 8, 2, buf);
 	return concat(string, strlen(string));
 }
 
diff --git a/hardware/arduino/sam/cores/arduino/WString.h b/hardware/arduino/sam/cores/arduino/WString.h
index 4b9e64e0b..0404f767a 100644
--- a/hardware/arduino/sam/cores/arduino/WString.h
+++ b/hardware/arduino/sam/cores/arduino/WString.h
@@ -69,8 +69,8 @@ public:
 	explicit String(unsigned int, unsigned char base=10);
 	explicit String(long, unsigned char base=10);
 	explicit String(unsigned long, unsigned char base=10);
-	explicit String(float, int decimalPlaces=6);
-	explicit String(double, int decimalPlaces=6);
+	explicit String(float, int decimalPlaces=2);
+	explicit String(double, int decimalPlaces=2);
 	~String(void);
 
 	// memory management
diff --git a/hardware/arduino/sam/libraries/SPI/SPI.cpp b/hardware/arduino/sam/libraries/SPI/SPI.cpp
index ef931a3f4..017ec4edb 100644
--- a/hardware/arduino/sam/libraries/SPI/SPI.cpp
+++ b/hardware/arduino/sam/libraries/SPI/SPI.cpp
@@ -13,13 +13,14 @@
 SPIClass::SPIClass(Spi *_spi, uint32_t _id, void(*_initCb)(void)) :
 	spi(_spi), id(_id), initCb(_initCb)
 {
-	initCb();
-
-	SPI_Configure(spi, id, SPI_MR_MSTR | SPI_MR_PS | SPI_MR_MODFDIS);
-	SPI_Enable(spi);
+	// Empty
 }
 
 void SPIClass::begin() {
+	initCb();
+	SPI_Configure(spi, id, SPI_MR_MSTR | SPI_MR_PS | SPI_MR_MODFDIS);
+	SPI_Enable(spi);
+
 	// NPCS control is left to the user
 
 	// Default speed set to 4Mhz
diff --git a/hardware/arduino/sam/variants/arduino_due_x/variant.h b/hardware/arduino/sam/variants/arduino_due_x/variant.h
index 75fd65474..ef2587688 100644
--- a/hardware/arduino/sam/variants/arduino_due_x/variant.h
+++ b/hardware/arduino/sam/variants/arduino_due_x/variant.h
@@ -84,7 +84,7 @@ extern "C"{
 #define BOARD_SPI_SS1        (4u)
 #define BOARD_SPI_SS2        (52u)
 #define BOARD_SPI_SS3        PIN_SPI_SS3
-#define BOARD_SPI_DEFAULT_SS BOARD_SPI_SS2
+#define BOARD_SPI_DEFAULT_SS BOARD_SPI_SS3
 
 #define BOARD_PIN_TO_SPI_PIN(x) \
 	(x==BOARD_SPI_SS0 ? PIN_SPI_SS0 : \