Quadrotor

/*

 * Copyright (c) 2010 by Cristian Maglie <c.maglie@bug.st>

 * SPI Master library for arduino.

 *

 * This file is free software; you can redistribute it and/or modify

 * it under the terms of either the GNU General Public License version 2

 * or the GNU Lesser General Public License version 2.1, both as

 * published by the Free Software Foundation.

 */

#include "pins_arduino.h"

#include "SPI.h"

SPIClass SPI;

void SPIClass::begin() {

  // Set direction register for SCK and MOSI pin.

  // MISO pin automatically overrides to INPUT.

  // When the SS pin is set as OUTPUT, it can be used as

  // a general purpose output port (it doesn't influence

  // SPI operations).

  pinMode(SCK, OUTPUT);

  pinMode(MOSI, OUTPUT);

  pinMode(SS, OUTPUT);

  digitalWrite(SCK, LOW);

  digitalWrite(MOSI, LOW);

  digitalWrite(SS, HIGH);

  // Warning: if the SS pin ever becomes a LOW INPUT then SPI 

  // automatically switches to Slave, so the data direction of 

  // the SS pin MUST be kept as OUTPUT.

  SPCR |= _BV(MSTR);

  SPCR |= _BV(SPE);

}

void SPIClass::end() {

  SPCR &= ~_BV(SPE);

}

void SPIClass::setBitOrder(uint8_t bitOrder)

{

  if(bitOrder == LSBFIRST) {

    SPCR |= _BV(DORD);

  } else {

    SPCR &= ~(_BV(DORD));

  }

}

void SPIClass::setDataMode(uint8_t mode)

{

  SPCR = (SPCR & ~SPI_MODE_MASK) | mode;

}

void SPIClass::setClockDivider(uint8_t rate)

{

  SPCR = (SPCR & ~SPI_CLOCK_MASK) | (rate & SPI_CLOCK_MASK);

  SPSR = (SPSR & ~SPI_2XCLOCK_MASK) | ((rate >> 2) & SPI_2XCLOCK_MASK);

}