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https://github.com/arduino/Arduino.git
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67 lines
1.7 KiB
C++
67 lines
1.7 KiB
C++
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/*
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* Copyright (c) 2010 by Cristian Maglie <c.maglie@bug.st>
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* SPI Master library for arduino.
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*
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* This file is free software; you can redistribute it and/or modify
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* it under the terms of either the GNU General Public License version 2
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* or the GNU Lesser General Public License version 2.1, both as
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* published by the Free Software Foundation.
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*/
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#include "pins_arduino.h"
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#include "SPI.h"
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SPIClass SPI;
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void SPIClass::begin() {
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// Set SS to high so a connected chip will be "deselected" by default
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digitalWrite(SS, HIGH);
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// When the SS pin is set as OUTPUT, it can be used as
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// a general purpose output port (it doesn't influence
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// SPI operations).
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pinMode(SS, OUTPUT);
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// Warning: if the SS pin ever becomes a LOW INPUT then SPI
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// automatically switches to Slave, so the data direction of
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// the SS pin MUST be kept as OUTPUT.
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SPCR |= _BV(MSTR);
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SPCR |= _BV(SPE);
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// Set direction register for SCK and MOSI pin.
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// MISO pin automatically overrides to INPUT.
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// By doing this AFTER enabling SPI, we avoid accidentally
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// clocking in a single bit since the lines go directly
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// from "input" to SPI control.
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// http://code.google.com/p/arduino/issues/detail?id=888
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pinMode(SCK, OUTPUT);
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pinMode(MOSI, OUTPUT);
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}
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void SPIClass::end() {
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SPCR &= ~_BV(SPE);
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}
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void SPIClass::setBitOrder(uint8_t bitOrder)
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{
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if(bitOrder == LSBFIRST) {
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SPCR |= _BV(DORD);
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} else {
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SPCR &= ~(_BV(DORD));
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}
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}
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void SPIClass::setDataMode(uint8_t mode)
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{
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SPCR = (SPCR & ~SPI_MODE_MASK) | mode;
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}
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void SPIClass::setClockDivider(uint8_t rate)
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{
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SPCR = (SPCR & ~SPI_CLOCK_MASK) | (rate & SPI_CLOCK_MASK);
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SPSR = (SPSR & ~SPI_2XCLOCK_MASK) | ((rate >> 2) & SPI_2XCLOCK_MASK);
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}
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