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/*
* 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 SS to high so a connected chip will be "deselected" by default
digitalWrite(SS, HIGH);
// 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(SS, OUTPUT);
// 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);
// Set direction register for SCK and MOSI pin.
// MISO pin automatically overrides to INPUT.
// By doing this AFTER enabling SPI, we avoid accidentally
// clocking in a single bit since the lines go directly
// from "input" to SPI control.
// http://code.google.com/p/arduino/issues/detail?id=888
pinMode(SCK, OUTPUT);
pinMode(MOSI, OUTPUT);
}
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);
}
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