i2c.h

12232液晶单片机驱动程序源代码

//------------------------------------------------------------------------------------
//
// Copyright 2001 Cygnal Integrated Products, Inc.
//
// FILE NAME      : SMB_Ex2.c
// TARGET DEVICE  : C8051F000
// CREATED ON     : 2/20/01
// CREATED BY     : JS
//
//
// Example code for interfacing a C8051F0xx to three EEPROMs via the SMBus.
// Code assumes that three 16-bit address space EEPROMs are connected
// on the SCL and SDA lines, and configured so that their slave addresses
// are as follows:
// CHIP_A = 1010000
// CHIP_B = 1010001
// CHIP_C = 1010010
//
// Slave and arbitration states are not defined.  Assume the CF000 is the only
// master in the system.
// Functions: SM_Send performs a 1-byte write to the specified EEPROM
// SM_Receive performs a 1-byte read of the specified EEPROM address (both include
// memory address references).
//
// Includes test code section.
//------------------------------------------------------------------------------------

#define WRITE 0x00                  // SMBus WRITE command
#define READ  0x01                  // SMBus READ command

// Device addresses (7 bits, lsb is a don't care)
#define CHIP_A 0xA0                 // Device address for chip A
#define CHIP_B 0xA2                 // Device address for chip B
#define CHIP_C 0xA4                 // Device address for chip C

// SMBus states:
// MT = Master Transmitter
// MR = Master Receiver
#define  SMB_BUS_ERROR  0x00        // (all modes) BUS ERROR
#define  SMB_START      0x08        // (MT & MR) START transmitted
#define  SMB_RP_START   0x10        // (MT & MR) repeated START
#define  SMB_MTADDACK   0x18        // (MT) Slave address + W transmitted;
                                    //  ACK received
#define  SMB_MTADDNACK  0x20        // (MT) Slave address + W transmitted;
                                    //  NACK received
#define  SMB_MTDBACK    0x28        // (MT) data byte transmitted; ACK rec'vd
#define  SMB_MTDBNACK   0x30        // (MT) data byte transmitted; NACK rec'vd
#define  SMB_MTARBLOST  0x38        // (MT) arbitration lost
#define  SMB_MRADDACK   0x40        // (MR) Slave address + R transmitted;
                                    //  ACK received
#define  SMB_MRADDNACK  0x48        // (MR) Slave address + R transmitted;
                                    //  NACK received
#define  SMB_MRDBACK    0x50        // (MR) data byte rec'vd; ACK transmitted
#define  SMB_MRDBNACK   0x58        // (MR) data byte rec'vd; NACK transmitted


//-----------------------------------------------------------------------------------
//Global VARIABLES
//-----------------------------------------------------------------------------------
char COMMAND;                       // Holds the slave address + R/W bit for
                                    // use in the SMBus ISR.

char WORD;                          // Holds data to be transmitted by the SMBus
                                    // OR data that has just been received.

char BYTE_NUMBER;                   // Used by ISR to check what data has just been
                                    // sent - High address byte, Low byte, or data
                                    // byte

unsigned char HIGH_ADD, LOW_ADD;    // High & Low byte for EEPROM memory address

bit SM_BUSY;                        // This bit is set when a send or receive
                                    // is started. It is cleared by the
                                    // ISR when the operation is finished.

//------------------------------------------------------------------------------------
// Function PROTOTYPES
//------------------------------------------------------------------------------------

void SMBus_ISR (void);
void SM_Send (char chip_select, unsigned int byte_address, char out_byte);
char SM_Receive (char chip_select, unsigned int byte_address);