/* 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 AVR Software I2C library
*
* @defgroup softI2C Software I2C
* @details Software Two Wire Interface library.
* @{
*/
#if defined(__AVR__) || defined(DOXYGEN) // AVR only
#include <Arduino.h>
#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;
bool transfer(uint8_t addressRW, void *buf,
size_t nbyte, uint8_t option = I2C_STOP);
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 AVR Software I2C master class
*/
class SoftI2cMaster : public I2cMasterBase
{
public:
SoftI2cMaster() {}
SoftI2cMaster(uint8_t sclPin, uint8_t sdaPin);
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 AVR 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)
{
fastDdrWrite(sclPin, !value);
}
//----------------------------------------------------------------------------
inline __attribute__((always_inline))
void sdaWrite(bool value)
{
fastDdrWrite(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 // __AVR__
#endif // SOFT_I2C_MASTER_H
/** @} */