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1e0f968387
This should prevent conflicts between an SPI device using the hardware SS pin (which previously would have been enabled by default) and another SPI device using another pin for its SS. It might be better to move the SPI initialization to begin(), which could then be called by the hardware devices which could then disable themselves.
88 lines
2.0 KiB
C++
88 lines
2.0 KiB
C++
/*
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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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SPIClass::SPIClass()
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{
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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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// 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(SCK, OUTPUT);
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pinMode(MOSI, OUTPUT);
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pinMode(SS, OUTPUT);
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digitalWrite(SCK, LOW);
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digitalWrite(MOSI, LOW);
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digitalWrite(SS, HIGH);
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SPCR = _BV(SPE) | _BV(MSTR);
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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(SPE) | _BV(MSTR);
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}
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void SPIClass::setDataOrder(SPIDataOrder _d)
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{
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if (_d == SPI_DataOrder_LSB)
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SPCR |= _BV(DORD); // LSB
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else
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SPCR &= ~_BV(DORD); // MSB
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}
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void SPIClass::setSPIMode(SPIMode _d)
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{
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switch (_d) {
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case SPI_Mode_SampleRising:
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SPCR &= ~(_BV(CPOL) | _BV(CPHA));
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break;
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case SPI_Mode_SetupRising:
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SPCR &= ~_BV(CPOL);
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SPCR |= _BV(CPHA);
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break;
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case SPI_Mode_SampleFalling:
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SPCR &= ~_BV(CPHA);
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SPCR |= _BV(CPOL);
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break;
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case SPI_Mode_SetupFalling:
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SPCR |= _BV(CPOL) | _BV(CPHA);
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break;
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}
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}
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void SPIClass::setClockDivider(SPIClockDivider _d)
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{
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switch (_d) {
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case SPI_ClkDiv_4:
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SPCR &= ~(_BV(SPR1) | _BV(SPR0));
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break;
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case SPI_ClkDiv_16:
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SPCR &= ~_BV(SPR1);
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SPCR |= _BV(SPR0);
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break;
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case SPI_ClkDiv_64:
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SPCR |= _BV(SPR1);
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SPCR &= ~_BV(SPR0);
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break;
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case SPI_ClkDiv_128:
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SPCR |= _BV(SPR1) | _BV(SPR0);
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break;
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}
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}
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