diff --git a/libraries/SPI3/SPI3.cpp b/libraries/SPI3/SPI3.cpp
new file mode 100644
index 0000000000..510046664b
--- /dev/null
+++ b/libraries/SPI3/SPI3.cpp
@@ -0,0 +1,93 @@
+/*
+ *       SPI3.cpp - SPI library using UART3 for Ardupilot Mega
+ *       Code by Randy Mackay, DIYDrones.com 
+ *       but mostly based on standard Arduino SPI class by Cristian Maglie <c.maglie@bug.st>
+ *
+ *       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.
+ *
+ */
+
+#include "pins_arduino.h"
+#include "SPI3.h"
+
+SPI3Class SPI3;
+bool SPI3Class::_initialised = false;
+
+void SPI3Class::begin() {
+
+    // check if begin has been run already
+    if( _initialised ) {
+        return;
+    }
+
+    // Set direction register for SCK and MOSI pin.
+    pinMode(SPI3_SCK, OUTPUT);
+    pinMode(SPI3_MOSI, OUTPUT);
+    pinMode(SPI3_MISO, INPUT);
+
+    // Setup Serial Port3 in SPI mode (MSPI), Mode 0, Clock: 8Mhz
+    UBRR3 = 0;
+    DDRJ |= (1<<PJ2);   // SPI clock XCK3 (PJ2) as output. This enable SPI Master mode
+
+    // put UART3 into SPI master mode, default mode and LSB bit order 
+    UCSR3C = SPI3_USART_SPI_MASTER | SPI3_DEFAULT_MODE;
+
+    // Enable receiver and transmitter.
+    UCSR3B = (1<<RXEN3)|(1<<TXEN3);
+
+    // Set Baud rate
+    UBRR3 = SPI3_DEFAULT_SPEED;    // SPI running at 2Mhz by default
+
+    // initialisation complete
+    _initialised = true;
+}
+
+// end - switch UART3 back to asyncronous UART
+// Note: this is untested
+void SPI3Class::end() {
+    uint8_t temp = UCSR3C;
+    
+    // put UART3 into ASync UART mode
+    temp = (temp & ~SPI3_USART_MASK) | SPI3_USART_ASYNC_UART;
+    UCSR3C = temp;
+
+    // reinitialisation will be required
+    _initialised = false;
+}
+
+uint8_t SPI3Class::transfer(uint8_t data) {
+    /* Wait for empty transmit buffer */
+    while ( !( UCSR3A & (1<<UDRE3)) ) ;
+
+    /* Put data into buffer, sends the data */
+    UDR3 = data;
+
+    /* Wait for data to be received */
+    while ( !(UCSR3A & (1<<RXC3)) ) ;
+
+    /* Get and return received data from buffer */
+    return UDR3;
+}
+
+void SPI3Class::setBitOrder(uint8_t bitOrder)
+{
+  if(bitOrder == SPI3_LSBFIRST) {
+    UCSR3C |= _BV(2);
+  } else {
+    UCSR3C &= ~(_BV(2));
+  }
+}
+
+void SPI3Class::setDataMode(uint8_t mode)
+{
+  UCSR3C = (UCSR3C & ~SPI3_MODE_MASK) | mode;
+}
+
+void SPI3Class::setSpeed(uint8_t rate)
+{
+  UBRR3 = rate;
+}
+
diff --git a/libraries/SPI3/SPI3.h b/libraries/SPI3/SPI3.h
new file mode 100644
index 0000000000..2e0745bec8
--- /dev/null
+++ b/libraries/SPI3/SPI3.h
@@ -0,0 +1,70 @@
+/*
+ *       SPI3.cpp - SPI library using UART3 for Ardupilot Mega
+ *       Code by Randy Mackay. DIYDrones.com
+ *
+ *       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.
+ *
+ */
+
+#ifndef _SPI3_H_INCLUDED
+#define _SPI3_H_INCLUDED
+
+#include <stdio.h>
+#include <Arduino.h>
+#include <avr/pgmspace.h>
+
+// SPI3's standard pins on Atmega2560
+#define SPI3_SCK        PJ2
+#define SPI3_MOSI       14
+#define SPI3_MISO       15
+
+// used to change UART into SPI mode
+#define SPI3_USART_MASK         0xC0      // UMSEL31 | UMSEL30
+#define SPI3_USART_ASYNC_UART   0x00      // UMSEL31 = 0, UMSEL30 = 0
+#define SPI3_USART_SYNC_UART    0x40      // UMSEL31 = 0, UMSEL30 = 1
+#define SPI3_USART_SPI_MASTER   0xC0      // UMSEL31 = 1, UMSEL30 = 1
+
+// spi bus speeds.  these assume a 16Mhz clock
+#define SPI3_SPEED_8MHZ 0x00
+#define SPI3_SPEED_2MHZ 0x04
+
+// default speed
+#define SPI3_DEFAULT_SPEED SPI3_SPEED_2MHZ // 2 megahertz
+
+// SPI mode definitions
+#define SPI3_MODE_MASK 0x03
+#define SPI3_MODE0 0x00
+#define SPI3_MODE1 0x01
+#define SPI3_MODE2 0x02
+#define SPI3_MODE3 0x03
+#define SPI3_DEFAULT_MODE SPI3_MODE0
+
+#define SPI3_CLOCK_MASK 0x03  // SPR1 = bit 1, SPR0 = bit 0 on SPCR
+#define SPI3_2XCLOCK_MASK 0x01  // SPI2X = bit 0 on SPSR
+
+// SPI bit order
+#define SPI3_MSBFIRST 0x00
+#define SPI3_LSBFIRST 0x01
+
+class SPI3Class {
+public:
+
+    static void begin();
+    static void end();
+    static uint8_t transfer(byte data);
+
+    // SPI Configuration methods
+    static void setBitOrder(uint8_t bitOrder);
+    static void setDataMode(uint8_t mode);
+    static void setSpeed(uint8_t rate);
+
+private:
+    static bool _initialised;
+};
+
+extern SPI3Class SPI3;
+
+#endif
diff --git a/libraries/SPI3/examples/SPI3_test/SPI3_test.pde b/libraries/SPI3/examples/SPI3_test/SPI3_test.pde
new file mode 100644
index 0000000000..68c472f1b4
--- /dev/null
+++ b/libraries/SPI3/examples/SPI3_test/SPI3_test.pde
@@ -0,0 +1,46 @@
+/*
+ *  Example of AP_OpticalFlow library.
+ *  Code by Randy Mackay. DIYDrones.com
+ */
+
+#include <FastSerial.h>
+#include <AP_Common.h>
+#include <AP_Math.h>            // ArduPilot Mega Vector/Matrix math Library
+#include <SPI3.h>                // Arduino SPI library
+
+////////////////////////////////////////////////////////////////////////////////
+// Serial ports
+////////////////////////////////////////////////////////////////////////////////
+//
+// Note that FastSerial port buffers are allocated at ::begin time,
+// so there is not much of a penalty to defining ports that we don't
+// use.
+//
+FastSerialPort0(Serial);        // FTDI/console
+
+void setup()
+{
+    Serial.begin(115200);
+    Serial.println("ArduPilot Mega SPI3 library test ver 0.1");
+
+    delay(1000);
+
+    // initialise SPI3 bus
+    SPI3.begin();
+    SPI3.setBitOrder(SPI3_MSBFIRST);
+    SPI3.setDataMode(SPI3_MODE0);
+    SPI3.setSpeed(SPI3_SPEED_2MHZ);
+
+    delay(1000);
+}
+
+void loop()
+{
+    int value;
+
+    // wait for user to enter something
+    while( !Serial.available() ) {
+        value = Serial.read();
+        delay(20);
+    }
+}
diff --git a/libraries/SPI3/keywords.txt b/libraries/SPI3/keywords.txt
new file mode 100644
index 0000000000..6c71457408
--- /dev/null
+++ b/libraries/SPI3/keywords.txt
@@ -0,0 +1,36 @@
+#######################################
+# Syntax Coloring Map SPI
+#######################################
+
+#######################################
+# Datatypes (KEYWORD1)
+#######################################
+
+SPI3	KEYWORD1
+
+#######################################
+# Methods and Functions (KEYWORD2)
+#######################################
+begin	KEYWORD2
+end	KEYWORD2
+transfer	KEYWORD2
+setBitOrder	KEYWORD2
+setDataMode	KEYWORD2
+setSpeed	KEYWORD2
+
+
+#######################################
+# Constants (LITERAL1)
+#######################################
+SPI3_CLOCK_DIV4	LITERAL1
+SPI3_CLOCK_DIV16	LITERAL1
+SPI3_CLOCK_DIV64	LITERAL1
+SPI3_CLOCK_DIV128	LITERAL1
+SPI3_CLOCK_DIV2	LITERAL1
+SPI3_CLOCK_DIV8	LITERAL1
+SPI_CLOCK_DIV32	LITERAL1
+SPI3_CLOCK_DIV64	LITERAL1
+SPI3_MODE0	LITERAL1
+SPI3_MODE1	LITERAL1
+SPI3_MODE2	LITERAL1
+SPI3_MODE3	LITERAL1
\ No newline at end of file