MySensors/drivers/AVR/DigitalIO/SoftI2cMaster.h

/* Arduino DigitalIO Library
 * Copyright (C) 2013 by William Greiman
 *
 * This file is part of the Arduino DigitalIO Library
 *
 * This Library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This Library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with the Arduino DigitalIO Library.  If not, see
 * <http://www.gnu.org/licenses/>.
 */
#ifndef SOFT_I2C_MASTER_H
#define SOFT_I2C_MASTER_H
/**
 * @file
 * @brief Software I2C library
 *
 * @defgroup softI2C Software I2C
 * @ingroup internals
 * @details  Software Two Wire Interface library.
 * @{
 */
#if ARDUINO < 100
#error Requires Arduino 1.0 or greater.
#else  // ARDUINO
#include <Arduino.h>
#endif  // ARDUINO
#include <util/delay_basic.h>
#include "DigitalPin.h"
#include "I2cConstants.h"
//------------------------------------------------------------------------------
// State codes.

/** Stop condition transmitted. */
const uint8_t STATE_STOP = 0;

/** Repeated start condition transmitted. */
const uint8_t STATE_REP_START = 1;

/** Read data transfer active. */
const uint8_t STATE_RX_DATA = 2;

/** Write data transfer active. */
const uint8_t STATE_TX_DATA = 3;

/** Slave address plus read bit transmitted, NACK received. */
const uint8_t STATE_RX_ADDR_NACK = 4;

/** Slave address plus write bit transmitted, NACK received. */
const uint8_t STATE_TX_ADDR_NACK = 5;
/** Data byte transmitted, NACK received. */
const uint8_t STATE_TX_DATA_NACK = 6;
//==============================================================================
/**
 * @class I2cMasterBase
 * @brief Base class for FastI2cMaster, SoftI2cMaster
 */
class I2cMasterBase
{
public:
	I2cMasterBase() : _state(STATE_STOP) {}
	/** Read a byte
	 *
	 * @note This function should only be used by experts. Data should be
	 *       accessed by calling transfer() and transferContinue()
	 *
	 * @param[in] last send a NACK to terminate read if last is true else
	 *            send an ACK to continue the read.
	 *
	 * @return byte read from I2C bus
	 */
	virtual uint8_t read(uint8_t last) = 0;

	/** Issue a start condition
	 *
	 * @note This function should only be used by experts. Data should be
	 *       accessed by calling transfer() and transferContinue()
	 */
	virtual void start() = 0;
	/** Issue a stop condition.
	 *
	 * @note This function should only be used by experts. Data should be
	 *       accessed by calling transfer() and transferContinue()
	 */
	virtual void stop() = 0;

	/**
	 * Start an I2C transfer with possible continuation.
	 *
	 * @param[in] addressRW I2C slave address plus R/W bit.
	 *                      The I2C slave address is in the high seven bits
	 *                      and is ORed with on of the following:
	 *                      - I2C_READ for a read transfer.
	 *                      - I2C_WRITE for a write transfer.
	 *                      .
	 * @param[in,out] buf   Source or destination for transfer.
	 * @param[in] nbyte     Number of bytes to transfer (may be zero).
	 * @param[in] option    Option for ending the transfer, one of:
	 *                      - I2C_STOP end the transfer with an I2C stop
	 *                        condition.
	 *                      - I2C_REP_START end the transfer with an I2C
	 *                        repeated start condition.
	 *                      - I2C_CONTINUE allow additional transferContinue()
	 *                        calls.
	 *                      .
	 * @return true for success else false.
	 */
	bool transfer(uint8_t addressRW, void *buf,
	              size_t nbyte, uint8_t option = I2C_STOP);

	/**
	 * Continue an I2C transfer.
	 *
	 * @param[in,out] buf   Source or destination for transfer.
	 * @param[in] nbyte     Number of bytes to transfer (may be zero).
	 * @param[in] option    Option for ending the transfer, one of:
	 *                      - I2C_STOP end the transfer with an I2C stop
	 *                        condition.
	 *                      - I2C_REP_START end the transfer with an I2C
	 *                        repeated start condition.
	 *                      - I2C_CONTINUE allow additional transferContinue()
	 *                        calls.
	 *                      .
	 * @return true for success else false.
	 */
	bool transferContinue(void *buf, size_t nbyte, uint8_t option = I2C_STOP);
	/** Write a byte
	 *
	 * @note This function should only be used by experts. Data should be
	 *       accessed by calling transfer() and transferContinue()
	 *
	 * @param[in] data byte to write
	 * @return true for ACK or false for NACK */
	virtual bool write(uint8_t data) = 0;

private:
	uint8_t _state;
};
//==============================================================================
/**
 * @class SoftI2cMaster
 * @brief Software I2C master class
 */
class SoftI2cMaster : public I2cMasterBase
{
public:
	SoftI2cMaster() {}
	/**
	 * Constructor, initialize SCL/SDA pins and set the bus high.
	 *
	 * @param[in] sdaPin The software SDA pin number.
	 *
	 * @param[in] sclPin The software SCL pin number.
	 */
	SoftI2cMaster(uint8_t sclPin, uint8_t sdaPin);
	/**
	 * Initialize SCL/SDA pins and set the bus high.
	 *
	 * @param[in] sdaPin The software SDA pin number.
	 *
	 * @param[in] sclPin The software SCL pin number.
	 */
	void begin(uint8_t sclPin, uint8_t sdaPin);
	uint8_t read(uint8_t last);
	void start();
	void stop(void);
	bool write(uint8_t b);

private:
	uint8_t _sclBit;
	uint8_t _sdaBit;
	volatile uint8_t* _sclDDR;
	volatile uint8_t* _sdaDDR;
	volatile uint8_t* _sdaInReg;
	//----------------------------------------------------------------------------
	bool readSda()
	{
		return *_sdaInReg & _sdaBit;
	}
	//----------------------------------------------------------------------------
	void sclDelay(uint8_t n)
	{
		_delay_loop_1(n);
	}
	//----------------------------------------------------------------------------
	void writeScl(bool value)
	{
		uint8_t s = SREG;
		noInterrupts();
		if (value == LOW) {
			// Pull scl low.
			*_sclDDR |= _sclBit;
		} else {
			// Put scl in high Z  input mode.
			*_sclDDR &= ~_sclBit;
		}
		SREG = s;
	}
	//----------------------------------------------------------------------------
	void writeSda(bool value)
	{
		uint8_t s = SREG;
		noInterrupts();
		if (value == LOW) {
			// Pull sda low.
			*_sdaDDR |= _sdaBit;
		} else {
			// Put sda in high Z input mode.
			*_sdaDDR &= ~_sdaBit;
		}
		SREG = s;
	}
};
//==============================================================================
// Template based fast software I2C
//------------------------------------------------------------------------------
/**
 * @class FastI2cMaster
 * @brief Fast software I2C master class.
 */
template<uint8_t sclPin, uint8_t sdaPin>
class FastI2cMaster : public I2cMasterBase
{
public:
	//----------------------------------------------------------------------------
	FastI2cMaster()
	{
		begin();
	}
	//----------------------------------------------------------------------------
	/** Initialize I2C bus pins. */
	void begin()
	{
		fastDigitalWrite(sclPin, LOW);
		fastDigitalWrite(sdaPin, LOW);

		sclWrite(HIGH);
		sdaWrite(HIGH);
	}
	//----------------------------------------------------------------------------
	uint8_t read(uint8_t last)
	{
		uint8_t data = 0;
		sdaWrite(HIGH);

		readBit(7, &data);
		readBit(6, &data);
		readBit(5, &data);
		readBit(4, &data);
		readBit(3, &data);
		readBit(2, &data);
		readBit(1, &data);
		readBit(0, &data);

		// send ACK or NACK
		sdaWrite(last);
		sclDelay(4);
		sclWrite(HIGH);
		sclDelay(6);
		sclWrite(LOW);
		sdaWrite(LOW);
		return data;
	}
	//----------------------------------------------------------------------------
	void start()
	{
		if (!fastDigitalRead(sdaPin)) {
			// It's a repeat start.
			sdaWrite(HIGH);
			sclDelay(8);
			sclWrite(HIGH);
			sclDelay(8);
		}
		sdaWrite(LOW);
		sclDelay(8);
		sclWrite(LOW);
		sclDelay(8);
	}
	//----------------------------------------------------------------------------
	void stop(void)
	{
		sdaWrite(LOW);
		sclDelay(8);
		sclWrite(HIGH);
		sclDelay(8);
		sdaWrite(HIGH);
		sclDelay(8);
	}
	//----------------------------------------------------------------------------
	bool write(uint8_t data)
	{
		// write byte
		writeBit(7, data);
		writeBit(6, data);
		writeBit(5, data);
		writeBit(4, data);
		writeBit(3, data);
		writeBit(2, data);
		writeBit(1, data);
		writeBit(0, data);

		// get ACK or NACK
		sdaWrite(HIGH);

		sclWrite(HIGH);
		sclDelay(5);
		bool rtn = fastDigitalRead(sdaPin);
		sclWrite(LOW);
		sdaWrite(LOW);
		return rtn == 0;
	}

private:
	//----------------------------------------------------------------------------
	inline __attribute__((always_inline))
	void sclWrite(bool value)
	{
		fastPinMode(sclPin, !value);
	}
	//----------------------------------------------------------------------------
	inline __attribute__((always_inline))
	void sdaWrite(bool value)
	{
		fastPinMode(sdaPin, !value);
	}
	//----------------------------------------------------------------------------
	inline __attribute__((always_inline))
	void readBit(uint8_t bit, uint8_t* data)
	{
		sclWrite(HIGH);
		sclDelay(5);
		if (fastDigitalRead(sdaPin)) {
			*data |= 1 << bit;
		}
		sclWrite(LOW);
		if (bit) {
			sclDelay(6);
		}
	}
	//----------------------------------------------------------------------------
	void sclDelay(uint8_t n)
	{
		_delay_loop_1(n);
	}
	//----------------------------------------------------------------------------
	inline __attribute__((always_inline))
	void writeBit(uint8_t bit, uint8_t data)
	{
		uint8_t mask = 1 << bit;
		sdaWrite(data & mask);
		sclWrite(HIGH);
		sclDelay(5);
		sclWrite(LOW);
		sclDelay(5);
	}
};
#endif  // SOFT_I2C_MASTER_H
/** @} */