i2c.h.txt

基于AVR系列单片机实现i2c通信

00001 /*! \file i2c.h \brief I2C interface using AVR Two-Wire Interface (TWI) hardware. */
00002 //*****************************************************************************
00003 //
00004 // File Name    : 'i2c.h'
00005 // Title        : I2C interface using AVR Two-Wire Interface (TWI) hardware
00006 // Author       : Pascal Stang - Copyright (C) 2002-2003
00007 // Created      : 2002.06.25
00008 // Revised      : 2003.03.03
00009 // Version      : 0.9
00010 // Target MCU   : Atmel AVR series
00011 // Editor Tabs  : 4
00012 //
00013 /// \ingroup driver_avr
00014 /// \defgroup i2c I2C Serial Interface Function Library (i2c.c)
00015 /// \code #include "i2c.h" \endcode
00016 /// \par Overview
00017 ///     This library provides the high-level functions needed to use the I2C
00018 /// serial interface supported by the hardware of several AVR processors.
00019 /// The library is functional but has not been exhaustively tested yet and is
00020 /// still expanding.? Thanks to the standardization of the I2C protocol and
00021 /// register access, the send and receive commands are everything you need to
00022 /// talk to thousands of different I2C devices including: EEPROMS, Flash memory,
00023 /// MP3 players, A/D and D/A converters, electronic potentiometers, etc.
00024 ///
00025 /// \par About I2C
00026 ///         I2C (pronounced "eye-squared-see") is a two-wire bidirectional
00027 ///     network designed for easy transfer of information between a wide variety
00028 ///     of intelligent devices.  Many of the Atmel AVR series processors have
00029 ///     hardware support for transmitting and receiving using an I2C-type bus.
00030 ///     In addition to the AVRs, there are thousands of other parts made by
00031 ///     manufacturers like Philips, Maxim, National, TI, etc that use I2C as
00032 ///     their primary means of communication and control.  Common device types
00033 ///     are A/D & D/A converters, temp sensors, intelligent battery monitors,
00034 ///     MP3 decoder chips, EEPROM chips, multiplexing switches, etc.
00035 ///
00036 ///     I2C uses only two wires (SDA and SCL) to communicate bidirectionally
00037 ///     between devices.  I2C is a multidrop network, meaning that you can have
00038 ///     several devices on a single bus.  Because I2C uses a 7-bit number to
00039 ///     identify which device it wants to talk to, you cannot have more than
00040 ///     127 devices on a single bus.
00041 ///
00042 ///     I2C ordinarily requires two 4.7K pull-up resistors to power (one each on
00043 ///     SDA and SCL), but for small numbers of devices (maybe 1-4), it is enough
00044 ///     to activate the internal pull-up resistors in the AVR processor.  To do
00045 ///     this, set the port pins, which correspond to the I2C pins SDA/SCL, high.
00046 ///     For example, on the mega163, sbi(PORTC, 0); sbi(PORTC, 1);.
00047 ///
00048 ///     For complete information about I2C, see the Philips Semiconductor
00049 ///     website.  They created I2C and have the largest family of devices that
00050 ///     work with I2C.
00051 ///
00052 /// \Note: Many manufacturers market I2C bus devices under a different or generic
00053 ///     bus name like "Two-Wire Interface".  This is because Philips still holds
00054 ///     "I2C" as a trademark.  For example, SMBus and SMBus devices are hardware
00055 ///     compatible and closely related to I2C.  They can be directly connected
00056 ///     to an I2C bus along with other I2C devices are are generally accessed in
00057 ///     the same way as I2C devices.  SMBus is often found on modern motherboards
00058 ///     for temp sensing and other low-level control tasks.
00059 //
00060 // This code is distributed under the GNU Public License
00061 //      which can be found at http://www.gnu.org/licenses/gpl.txt
00062 //
00063 //*****************************************************************************
00064 
00065 #ifndef I2C_H
00066 #define I2C_H
00067 
00068 #include "global.h"
00069 
00070 // include project-specific configuration
00071 #include "i2cconf.h"
00072 
00073 // TWSR values (not bits)
00074 // (taken from avr-libc twi.h - thank you Marek Michalkiewicz)
00075 // Master
00076 #define TW_START                    0x08
00077 #define TW_REP_START                0x10
00078 // Master Transmitter
00079 #define TW_MT_SLA_ACK               0x18
00080 #define TW_MT_SLA_NACK              0x20
00081 #define TW_MT_DATA_ACK              0x28
00082 #define TW_MT_DATA_NACK             0x30
00083 #define TW_MT_ARB_LOST              0x38
00084 // Master Receiver
00085 #define TW_MR_ARB_LOST              0x38
00086 #define TW_MR_SLA_ACK               0x40
00087 #define TW_MR_SLA_NACK              0x48
00088 #define TW_MR_DATA_ACK              0x50
00089 #define TW_MR_DATA_NACK             0x58
00090 // Slave Transmitter
00091 #define TW_ST_SLA_ACK               0xA8
00092 #define TW_ST_ARB_LOST_SLA_ACK      0xB0
00093 #define TW_ST_DATA_ACK              0xB8
00094 #define TW_ST_DATA_NACK             0xC0
00095 #define TW_ST_LAST_DATA             0xC8
00096 // Slave Receiver
00097 #define TW_SR_SLA_ACK               0x60
00098 #define TW_SR_ARB_LOST_SLA_ACK      0x68
00099 #define TW_SR_GCALL_ACK             0x70
00100 #define TW_SR_ARB_LOST_GCALL_ACK    0x78
00101 #define TW_SR_DATA_ACK              0x80
00102 #define TW_SR_DATA_NACK             0x88
00103 #define TW_SR_GCALL_DATA_ACK        0x90
00104 #define TW_SR_GCALL_DATA_NACK       0x98
00105 #define TW_SR_STOP                  0xA0
00106 // Misc
00107 #define TW_NO_INFO                  0xF8
00108 #define TW_BUS_ERROR                0x00
00109 
00110 // defines and constants
00111 #define TWCR_CMD_MASK       0x0F
00112 #define TWSR_STATUS_MASK    0xF8
00113 
00114 // return values
00115 #define I2C_OK              0x00
00116 #define I2C_ERROR_NODEV     0x01
00117 
00118 // types
00119 typedef enum
00120 {
00121     I2C_IDLE = 0, I2C_BUSY = 1,
00122     I2C_MASTER_TX = 2, I2C_MASTER_RX = 3,
00123     I2C_SLAVE_TX = 4, I2C_SLAVE_RX = 5
00124 } eI2cStateType;
00125 
00126 // functions
00127 
00128 //! Initialize I2C (TWI) interface
00129 void i2cInit(void);
00130 
00131 //! Set the I2C transaction bitrate (in KHz)
00132 void i2cSetBitrate(u16 bitrateKHz);
00133 
00134 // I2C setup and configurations commands
00135 //! Set the local (AVR processor's) I2C device address
00136 void i2cSetLocalDeviceAddr(u08 deviceAddr, u08 genCallEn);
00137 
00138 //! Set the user function which handles receiving (incoming) data as a slave
00139 void i2cSetSlaveReceiveHandler(void (*i2cSlaveRx_func)(u08 receiveDataLength, u08* recieveData));
00140 //! Set the user function which handles transmitting (outgoing) data as a slave
00141 void i2cSetSlaveTransmitHandler(u08 (*i2cSlaveTx_func)(u08 transmitDataLengthMax, u08* transmitData));
00142 
00143 // Low-level I2C transaction commands 
00144 //! Send an I2C start condition in Master mode
00145 void i2cSendStart(void);
00146 //! Send an I2C stop condition in Master mode
00147 void i2cSendStop(void);
00148 //! Wait for current I2C operation to complete
00149 void i2cWaitForComplete(void);
00150 //! Send an (address|R/W) combination or a data byte over I2C
00151 void i2cSendByte(u08 data);
00152 //! Receive a data byte over I2C  
00153 // ackFlag = TRUE if recevied data should be ACK'ed
00154 // ackFlag = FALSE if recevied data should be NACK'ed
00155 void i2cReceiveByte(u08 ackFlag);
00156 //! Pick up the data that was received with i2cReceiveByte()
00157 u08 i2cGetReceivedByte(void);
00158 //! Get current I2c bus status from TWSR
00159 u08 i2cGetStatus(void);
00160 
00161 // high-level I2C transaction commands
00162 
00163 //! send I2C data to a device on the bus
00164 void i2cMasterSend(u08 deviceAddr, u08 length, u08 *data);
00165 //! receive I2C data from a device on the bus
00166 void i2cMasterReceive(u08 deviceAddr, u08 length, u08* data);
00167 
00168 //! send I2C data to a device on the bus (non-interrupt based)
00169 u08 i2cMasterSendNI(u08 deviceAddr, u08 length, u08* data);
00170 //! receive I2C data from a device on the bus (non-interrupt based)
00171 u08 i2cMasterReceiveNI(u08 deviceAddr, u08 length, u08 *data);
00172 
00173 //! Get the current high-level state of the I2C interface
00174 eI2cStateType i2cGetState(void);
00175 
00176 #endif


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