/* * 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); }