diff --git a/hardware/arduino/avr/libraries/SPI/SPI.h b/hardware/arduino/avr/libraries/SPI/SPI.h
index 5206a091843..a339fd34330 100644
--- a/hardware/arduino/avr/libraries/SPI/SPI.h
+++ b/hardware/arduino/avr/libraries/SPI/SPI.h
@@ -3,6 +3,7 @@
  * Copyright (c) 2014 by Paul Stoffregen <paul@pjrc.com> (Transaction API)
  * Copyright (c) 2014 by Matthijs Kooijman <matthijs@stdin.nl> (SPISettings AVR)
  * Copyright (c) 2014 by Andrew J. Kroll <xxxajk@gmail.com> (atomicity fixes)
+ * Copyright (c) 2016 by Pedro M. Ribeiro <pamribeirox@gmail.com> (transfer_out)
  * SPI Master library for arduino.
  *
  * This file is free software; you can redistribute it and/or modify
@@ -255,6 +256,25 @@ class SPIClass {
     while (!(SPSR & _BV(SPIF))) ;
     *p = SPDR;
   }
+  /*
+   * An alternative "output only" transfer that doesn't destroy the
+   * contents of the source buffer with the bytes returned from the
+   * slave device. 
+   * Some code simplifications and const enforcement
+   * Revision with speedup of about 25% in atmega328p tests
+   * NOTE: I can't explain that "*(p++ + 1);" being speedier than "*++p"
+   */ 
+  inline static void transfer_out(const void *buf, size_t count) {
+    if (count == 0) return;
+    const uint8_t *p = (uint8_t *)buf;
+    SPDR = *p;
+    while (--count > 0) {
+      uint8_t out = *(p++ + 1); // ugly but somehow results in a speedup!
+      while (!(SPSR & _BV(SPIF))) ; // last SPI transfer is over?
+      SPDR = out;
+    }
+    while (!(SPSR & _BV(SPIF))) ; // last SPI transfer is over?
+  }
   // After performing a group of transfers and releasing the chip select
   // signal, this function allows others to access the SPI bus
   inline static void endTransaction(void) {
diff --git a/hardware/arduino/sam/libraries/SPI/SPI.h b/hardware/arduino/sam/libraries/SPI/SPI.h
index ef5b5141a52..b8168ef5354 100644
--- a/hardware/arduino/sam/libraries/SPI/SPI.h
+++ b/hardware/arduino/sam/libraries/SPI/SPI.h
@@ -85,13 +85,13 @@ class SPIClass {
 	uint16_t transfer16(byte _pin, uint16_t _data, SPITransferMode _mode = SPI_LAST);
 	void transfer(byte _pin, void *_buf, size_t _count, SPITransferMode _mode = SPI_LAST);
 	// Transfer functions on default pin BOARD_SPI_DEFAULT_SS
-	byte transfer(uint8_t _data, SPITransferMode _mode = SPI_LAST) { return transfer(BOARD_SPI_DEFAULT_SS, _data, _mode); }
-	uint16_t transfer16(uint16_t _data, SPITransferMode _mode = SPI_LAST) { return transfer16(BOARD_SPI_DEFAULT_SS, _data, _mode); }
-	void transfer(void *_buf, size_t _count, SPITransferMode _mode = SPI_LAST) { transfer(BOARD_SPI_DEFAULT_SS, _buf, _count, _mode); }
+	inline byte transfer(uint8_t _data, SPITransferMode _mode = SPI_LAST) { return transfer(BOARD_SPI_DEFAULT_SS, _data, _mode); }
+	inline uint16_t transfer16(uint16_t _data, SPITransferMode _mode = SPI_LAST) { return transfer16(BOARD_SPI_DEFAULT_SS, _data, _mode); }
+	inline void transfer(void *_buf, size_t _count, SPITransferMode _mode = SPI_LAST) { transfer(BOARD_SPI_DEFAULT_SS, _buf, _count, _mode); }
 
 	// Transaction Functions
 	void usingInterrupt(uint8_t interruptNumber);
-	void beginTransaction(SPISettings settings) { beginTransaction(BOARD_SPI_DEFAULT_SS, settings); }
+	inline void beginTransaction(SPISettings settings) { beginTransaction(BOARD_SPI_DEFAULT_SS, settings); }
 	void beginTransaction(uint8_t pin, SPISettings settings);
 	void endTransaction(void);
 
@@ -112,9 +112,9 @@ class SPIClass {
 	void setClockDivider(uint8_t _pin, uint8_t);
 
 	// These methods sets the same parameters but on default pin BOARD_SPI_DEFAULT_SS
-	void setBitOrder(BitOrder _order) { setBitOrder(BOARD_SPI_DEFAULT_SS, _order); };
-	void setDataMode(uint8_t _mode) { setDataMode(BOARD_SPI_DEFAULT_SS, _mode); };
-	void setClockDivider(uint8_t _div) { setClockDivider(BOARD_SPI_DEFAULT_SS, _div); };
+	inline void setBitOrder(BitOrder _order) { setBitOrder(BOARD_SPI_DEFAULT_SS, _order); };
+	inline void setDataMode(uint8_t _mode) { setDataMode(BOARD_SPI_DEFAULT_SS, _mode); };
+	inline void setClockDivider(uint8_t _div) { setClockDivider(BOARD_SPI_DEFAULT_SS, _div); };
 
   private:
 	void init();
diff --git a/hardware/arduino/sam/platform.txt b/hardware/arduino/sam/platform.txt
index 9a7f52d0a7f..e8062501f85 100644
--- a/hardware/arduino/sam/platform.txt
+++ b/hardware/arduino/sam/platform.txt
@@ -97,7 +97,8 @@ tools.bossac.path={runtime.tools.bossac.path}
 tools.bossac.cmd=bossac
 tools.bossac.cmd.windows=bossac.exe
 
-tools.bossac.upload.params.verbose=-i -d
+#tools.bossac.upload.params.verbose=-i -d
+tools.bossac.upload.params.verbose=-i
 tools.bossac.upload.params.quiet=
 tools.bossac.upload.pattern="{path}/{cmd}" {upload.verbose} --port={serial.port.file} -U {upload.native_usb} -e -w -v -b "{build.path}/{build.project_name}.bin" -R