teensy-spi/SPI.cpp

/*
 * 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 "SPI.h"
#include "pins_arduino.h"

SPIClass SPI;


/**********************************************************/
/*     8 bit AVR-based boards                             */
/**********************************************************/

#if defined(__AVR__)

uint8_t SPIClass::interruptMode = 0;
uint8_t SPIClass::interruptMask = 0;
uint8_t SPIClass::interruptSave = 0;

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::usingInterrupt(uint8_t interruptNumber)
{
	uint8_t mask;

	if (interruptMode > 1) return;

	noInterrupts();
	switch (interruptNumber) {
	#ifdef SPI_INT0_MASK
	case 0: mask = SPI_INT0_MASK; break;
	#endif
	#ifdef SPI_INT1_MASK
	case 1: mask = SPI_INT1_MASK; break;
	#endif
	#ifdef SPI_INT2_MASK
	case 2: mask = SPI_INT2_MASK; break;
	#endif
	#ifdef SPI_INT3_MASK
	case 3: mask = SPI_INT3_MASK; break;
	#endif
	#ifdef SPI_INT4_MASK
	case 4: mask = SPI_INT4_MASK; break;
	#endif
	#ifdef SPI_INT5_MASK
	case 5: mask = SPI_INT5_MASK; break;
	#endif
	#ifdef SPI_INT6_MASK
	case 6: mask = SPI_INT6_MASK; break;
	#endif
	#ifdef SPI_INT7_MASK
	case 7: mask = SPI_INT7_MASK; break;
	#endif
	default:
		interruptMode = 2;
		interrupts();
		return;
	}
	interruptMode = 1;
	interruptMask |= mask;
	interrupts();
}


/**********************************************************/
/*     32 bit Teensy 3.0 and 3.1                          */
/**********************************************************/

#elif defined(__arm__) && defined(TEENSYDUINO)

uint8_t SPIClass::interruptMode = 0;
uint8_t SPIClass::interruptMask = 0;
uint8_t SPIClass::interruptSave = 0;

void SPIClass::begin()
{
	SIM_SCGC6 |= SIM_SCGC6_SPI0;
	SPI0_MCR = SPI_MCR_MDIS | SPI_MCR_HALT | SPI_MCR_PCSIS(0x1F);
	SPI0_CTAR0 = SPI_CTAR_FMSZ(7) | SPI_CTAR_PBR(0) | SPI_CTAR_BR(1) | SPI_CTAR_CSSCK(1);
	SPI0_CTAR1 = SPI_CTAR_FMSZ(15) | SPI_CTAR_PBR(0) | SPI_CTAR_BR(1) | SPI_CTAR_CSSCK(1);
	SPI0_MCR = SPI_MCR_MSTR | SPI_MCR_PCSIS(0x1F);
	SPCR.enable_pins(); // pins managed by SPCRemulation in avr_emulation.h
}

void SPIClass::end() {
	SPCR.disable_pins();
	SPI0_MCR = SPI_MCR_MDIS | SPI_MCR_HALT | SPI_MCR_PCSIS(0x1F);
}

void SPIClass::usingInterrupt(uint8_t interruptNumber)
{
	// TODO: implement this...
}

void SPIClass::usingInterrupt(IRQ_NUMBER_t interruptName)
{
	// TODO: implement this...
}



const uint16_t SPISettings::ctar_div_table[23] = {
	2, 3, 4, 5, 6, 8, 10, 12, 16, 20, 24, 32, 40,
	56, 64, 96, 128, 192, 256, 384, 512, 640, 768
};
const uint32_t SPISettings::ctar_clock_table[23] = {
	SPI_CTAR_PBR(0) | SPI_CTAR_BR(0) | SPI_CTAR_DBR | SPI_CTAR_CSSCK(0),
	SPI_CTAR_PBR(1) | SPI_CTAR_BR(0) | SPI_CTAR_DBR | SPI_CTAR_CSSCK(0),
	SPI_CTAR_PBR(0) | SPI_CTAR_BR(0) | SPI_CTAR_CSSCK(0),
	SPI_CTAR_PBR(2) | SPI_CTAR_BR(0) | SPI_CTAR_DBR | SPI_CTAR_CSSCK(0),
	SPI_CTAR_PBR(1) | SPI_CTAR_BR(0) | SPI_CTAR_CSSCK(0),
	SPI_CTAR_PBR(0) | SPI_CTAR_BR(1) | SPI_CTAR_CSSCK(1),
	SPI_CTAR_PBR(2) | SPI_CTAR_BR(0) | SPI_CTAR_CSSCK(0),
	SPI_CTAR_PBR(1) | SPI_CTAR_BR(1) | SPI_CTAR_CSSCK(1),
	SPI_CTAR_PBR(0) | SPI_CTAR_BR(3) | SPI_CTAR_CSSCK(2),
	SPI_CTAR_PBR(2) | SPI_CTAR_BR(1) | SPI_CTAR_CSSCK(0),
	SPI_CTAR_PBR(1) | SPI_CTAR_BR(3) | SPI_CTAR_CSSCK(2),
	SPI_CTAR_PBR(0) | SPI_CTAR_BR(4) | SPI_CTAR_CSSCK(3),
	SPI_CTAR_PBR(2) | SPI_CTAR_BR(3) | SPI_CTAR_CSSCK(2),
	SPI_CTAR_PBR(3) | SPI_CTAR_BR(3) | SPI_CTAR_CSSCK(2),
	SPI_CTAR_PBR(0) | SPI_CTAR_BR(5) | SPI_CTAR_CSSCK(4),
	SPI_CTAR_PBR(1) | SPI_CTAR_BR(5) | SPI_CTAR_CSSCK(4),
	SPI_CTAR_PBR(0) | SPI_CTAR_BR(6) | SPI_CTAR_CSSCK(5),
	SPI_CTAR_PBR(1) | SPI_CTAR_BR(6) | SPI_CTAR_CSSCK(5),
	SPI_CTAR_PBR(0) | SPI_CTAR_BR(7) | SPI_CTAR_CSSCK(6),
	SPI_CTAR_PBR(1) | SPI_CTAR_BR(7) | SPI_CTAR_CSSCK(6),
	SPI_CTAR_PBR(0) | SPI_CTAR_BR(8) | SPI_CTAR_CSSCK(7),
	SPI_CTAR_PBR(2) | SPI_CTAR_BR(7) | SPI_CTAR_CSSCK(6),
	SPI_CTAR_PBR(1) | SPI_CTAR_BR(8) | SPI_CTAR_CSSCK(7)
};

static void updateCTAR(uint32_t ctar)
{
	if (SPI0_CTAR0 != ctar) {
		uint32_t mcr = SPI0_MCR;
		if (mcr & SPI_MCR_MDIS) {
			SPI0_CTAR0 = ctar;
			SPI0_CTAR1 = ctar | SPI_CTAR_FMSZ(8);
		} else {
			SPI0_MCR = SPI_MCR_MDIS | SPI_MCR_HALT | SPI_MCR_PCSIS(0x1F);
			SPI0_CTAR0 = ctar;
			SPI0_CTAR1 = ctar | SPI_CTAR_FMSZ(8);
			SPI0_MCR = mcr;
		}
	}
}

void SPIClass::setBitOrder(uint8_t bitOrder)
{
	SIM_SCGC6 |= SIM_SCGC6_SPI0;
	uint32_t ctar = SPI0_CTAR0;
	if (bitOrder == LSBFIRST) {
		ctar |= SPI_CTAR_LSBFE;
	} else {
		ctar &= ~SPI_CTAR_LSBFE;
	}
	updateCTAR(ctar);
}

void SPIClass::setDataMode(uint8_t dataMode)
{
	SIM_SCGC6 |= SIM_SCGC6_SPI0;

	// TODO: implement with native code

	SPCR = (SPCR & ~SPI_MODE_MASK) | dataMode;
}

void SPIClass::setClockDivider_noInline(uint32_t clk)
{
	SIM_SCGC6 |= SIM_SCGC6_SPI0;
	uint32_t ctar = SPI0_CTAR0;
	ctar &= (SPI_CTAR_CPOL | SPI_CTAR_CPHA | SPI_CTAR_LSBFE);
	if (ctar & SPI_CTAR_CPHA) {
		clk = (clk & 0xFFFF0FFF) | ((clk & 0xF000) >> 4);
	}
	ctar |= clk;
	updateCTAR(ctar);
}


#endif