i2c.h

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/*! \file i2c.h \brief I2C interface using AVR Two-Wire Interface (TWI) hardware. */
//*****************************************************************************
//
// File Name    : 'i2c.h'
// Title        : I2C interface using AVR Two-Wire Interface (TWI) hardware
// Author       : Pascal Stang - Copyright (C) 2002-2003
// Created      : 2002.06.25
// Revised      : 2003.03.03
// Version      : 0.9
// Target MCU   : Atmel AVR series
// Editor Tabs  : 4
//
/// \ingroup driver_avr
/// \defgroup i2c I2C Serial Interface Function Library (i2c.c)
/// \code #include "i2c.h" \endcode
/// \par Overview
///     This library provides the high-level functions needed to use the I2C
/// serial interface supported by the hardware of several AVR processors.
/// The library is functional but has not been exhaustively tested yet and is
/// still expanding.  Thanks to the standardization of the I2C protocol and
/// register access, the send and receive commands are everything you need to
/// talk to thousands of different I2C devices including: EEPROMS, Flash memory,
/// MP3 players, A/D and D/A converters, electronic potentiometers, etc.
///
/// \par About I2C
///         I2C (pronounced "eye-squared-see") is a two-wire bidirectional
///     network designed for easy transfer of information between a wide variety
///     of intelligent devices.  Many of the Atmel AVR series processors have
///     hardware support for transmitting and receiving using an I2C-type bus.
///     In addition to the AVRs, there are thousands of other parts made by
///     manufacturers like Philips, Maxim, National, TI, etc that use I2C as
///     their primary means of communication and control.  Common device types
///     are A/D & D/A converters, temp sensors, intelligent battery monitors,
///     MP3 decoder chips, EEPROM chips, multiplexing switches, etc.
///
///     I2C uses only two wires (SDA and SCL) to communicate bidirectionally
///     between devices.  I2C is a multidrop network, meaning that you can have
///     several devices on a single bus.  Because I2C uses a 7-bit number to
///     identify which device it wants to talk to, you cannot have more than
///     127 devices on a single bus.
///
///     I2C ordinarily requires two 4.7K pull-up resistors to power (one each on
///     SDA and SCL), but for small numbers of devices (maybe 1-4), it is enough
///     to activate the internal pull-up resistors in the AVR processor.  To do
///     this, set the port pins, which correspond to the I2C pins SDA/SCL, high.
///     For example, on the mega163, sbi(PORTC, 0); sbi(PORTC, 1);.
///
///     For complete information about I2C, see the Philips Semiconductor
///     website.  They created I2C and have the largest family of devices that
///     work with I2C.
///
/// \Note: Many manufacturers market I2C bus devices under a different or generic
///     bus name like "Two-Wire Interface".  This is because Philips still holds
///     "I2C" as a trademark.  For example, SMBus and SMBus devices are hardware
///     compatible and closely related to I2C.  They can be directly connected
///     to an I2C bus along with other I2C devices are are generally accessed in
///     the same way as I2C devices.  SMBus is often found on modern motherboards
///     for temp sensing and other low-level control tasks.
//
// This code is distributed under the GNU Public License
//      which can be found at http://www.gnu.org/licenses/gpl.txt
//
//*****************************************************************************

#ifndef I2C_H
#define I2C_H

#include "global.h"

// include project-specific configuration
#include "i2cconf.h"

// TWSR values (not bits)
// (taken from avr-libc twi.h - thank you Marek Michalkiewicz)
// Master
#define TW_START                    0x08
#define TW_REP_START                0x10
// Master Transmitter
#define TW_MT_SLA_ACK               0x18
#define TW_MT_SLA_NACK              0x20
#define TW_MT_DATA_ACK              0x28
#define TW_MT_DATA_NACK             0x30
#define TW_MT_ARB_LOST              0x38
// Master Receiver
#define TW_MR_ARB_LOST              0x38
#define TW_MR_SLA_ACK               0x40
#define TW_MR_SLA_NACK              0x48
#define TW_MR_DATA_ACK              0x50
#define TW_MR_DATA_NACK             0x58
// Slave Transmitter
#define TW_ST_SLA_ACK               0xA8
#define TW_ST_ARB_LOST_SLA_ACK      0xB0
#define TW_ST_DATA_ACK              0xB8
#define TW_ST_DATA_NACK             0xC0
#define TW_ST_LAST_DATA             0xC8
// Slave Receiver
#define TW_SR_SLA_ACK               0x60
#define TW_SR_ARB_LOST_SLA_ACK      0x68
#define TW_SR_GCALL_ACK             0x70
#define TW_SR_ARB_LOST_GCALL_ACK    0x78
#define TW_SR_DATA_ACK              0x80
#define TW_SR_DATA_NACK             0x88
#define TW_SR_GCALL_DATA_ACK        0x90
#define TW_SR_GCALL_DATA_NACK       0x98
#define TW_SR_STOP                  0xA0
// Misc
#define TW_NO_INFO                  0xF8
#define TW_BUS_ERROR                0x00

// defines and constants
#define TWCR_CMD_MASK       0x0F
#define TWSR_STATUS_MASK    0xF8

// return values
#define I2C_OK              0x00
#define I2C_ERROR_NODEV     0x01

// types
typedef enum
{
    I2C_IDLE = 0, I2C_BUSY = 1,
    I2C_MASTER_TX = 2, I2C_MASTER_RX = 3,
    I2C_SLAVE_TX = 4, I2C_SLAVE_RX = 5
} eI2cStateType;

// functions

//! Initialize I2C (TWI) interface
void i2cInit(void);

//! Set the I2C transaction bitrate (in KHz)
void i2cSetBitrate(u16 bitrateKHz);

// I2C setup and configurations commands
//! Set the local (AVR processor's) I2C device address
void i2cSetLocalDeviceAddr(u08 deviceAddr, u08 genCallEn);

//! Set the user function which handles receiving (incoming) data as a slave
void i2cSetSlaveReceiveHandler(void (*i2cSlaveRx_func)(u08 receiveDataLength, u08* recieveData));
//! Set the user function which handles transmitting (outgoing) data as a slave
void i2cSetSlaveTransmitHandler(u08 (*i2cSlaveTx_func)(u08 transmitDataLengthMax, u08* transmitData));

// Low-level I2C transaction commands 
//! Send an I2C start condition in Master mode
void i2cSendStart(void);
//! Send an I2C stop condition in Master mode
void i2cSendStop(void);
//! Wait for current I2C operation to complete
void i2cWaitForComplete(void);
//! Send an (address|R/W) combination or a data byte over I2C
void i2cSendByte(u08 data);
//! Receive a data byte over I2C  
// ackFlag = TRUE if recevied data should be ACK'ed
// ackFlag = FALSE if recevied data should be NACK'ed
void i2cReceiveByte(u08 ackFlag);
//! Pick up the data that was received with i2cReceiveByte()
u08 i2cGetReceivedByte(void);
//! Get current I2c bus status from TWSR
u08 i2cGetStatus(void);

// high-level I2C transaction commands

//! send I2C data to a device on the bus
void i2cMasterSend(u08 deviceAddr, u08 length, u08 *data);
//! receive I2C data from a device on the bus
void i2cMasterReceive(u08 deviceAddr, u08 length, u08* data);

//! send I2C data to a device on the bus (non-interrupt based)
u08 i2cMasterSendNI(u08 deviceAddr, u08 length, u08* data);
//! receive I2C data from a device on the bus (non-interrupt based)
u08 i2cMasterReceiveNI(u08 deviceAddr, u08 length, u08 *data);

//! Get the current high-level state of the I2C interface
eI2cStateType i2cGetState(void);

#endif

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