I2C通讯的C语言程序

#include <INTRINS.H>

#include <stdio.h>

#include <reg51.h>

sbit SCK=0x91;//时钟线端口

sbit SDA=0x90;//数据线端口

#define I2C_Address 0xa0 //I2C芯片地址

#define nop _nop_()

#define NOP nop;nop;nop;nop;nop;nop//延时应大于4.7us

//开始信号

//在时钟线为高电平时,数据线由高向低跳变.

void StartI2C(void)

{ SCK=1;

SDA=1;

NOP;

SDA=0;

NOP;

SCK=0;

NOP;

}

//停止信号

//在时钟线为高电平时,数据线由低向高跳变.

void StopI2C(void)

{ SDA=0;

NOP;

SCK=1;

NOP;

SDA=1;

}

//发送一个字节.

bit SendChar(unsigned char SendData)

{ unsigned char i;

bit ACK;

for(i=0;i<8;i++)

{ if((SendData<<i)&0x80)SDA=1;

else SDA=0;

SCK=1;

NOP;

SCK=0;

NOP;

}

//发送一个字节后,读取来自I2C芯片的响应.

//即在发送完8个字节后,在第九个时钟内,SDA总线应为低电平,表示I2C芯片已经读取了数据.

//否则为高电平.即发送收败.

SDA=1;

SCK=1;

NOP;

ACK=SDA;

SCK=0;

NOP;

return ACK;

}

//在读取完来自I2C的8位数据后,发出读取正确位.

//即发送一个低电平,表示已经读取到来自I2C的数据,并允许I2芯片发送下一字节.

void ACK(void)

{ SDA=0;

NOP;

SCK=1;

NOP;

SCK=0;

}

//在读取完来自I2C的8位数据后,发送不响应位.

//即发送一个高电平,表示已经读取完来自I2C的数据,并且不允许I2C发送下一字节.

void NAK(void)

{

SDA=1;

NOP;

SCK=1;

NOP;

SCK=0;

}

//读入一个字节的数据.

unsigned char ReadChar(void)

{ unsigned char i,BackData;

BackData=0;

SDA=1;

for(i=0;i<8;i++)

{ SCK=1;

nop;nop;nop;

BackData=BackData<<1;

if(SDA)BackData++;

SCK=0;

}

return BackData;

}

//以下所有为测试使用...

//应注意,在读I2C芯片时,在发送完I2C片内地址后,

//一定要发送一个重开始信号,然后再发送读命令.

bit WriteI2C(unsigned char Address,unsigned char WriteData)

{ SENDSTART:

StartI2C();

if(SendChar(I2C_Address)) goto SENDSTART;

SENDADD:

if(SendChar(Address)){StartI2C;goto SENDADD;}

SENDDATA:

if(SendChar(WriteData)){StartI2C;goto SENDDATA;}

if(SendChar(WriteData)){StartI2C;goto SENDDATA;}

StopI2C();

return 0;

}

unsigned char ReadI2C(unsigned char Address)

{ unsigned char BackData;

ReadSTART:

StartI2C();

if(SendChar(I2C_Address)) goto ReadSTART;

ReadADD:

if(SendChar(Address)){StartI2C;goto ReadADD;}

ReadSTART2:

StartI2C();

if(SendChar(I2C_Address+1)) goto ReadSTART2;

BackData=ReadChar();

ACK();

BackData=ReadChar();

NAK();

StopI2C();

return BackData;

}

void Delay(unsigned int ms)

{ unsigned int i,j;

for(i=0;i<ms;i++)

for(j=0;j<240;j++);

}

void main(void)

{ bit j;

unsigned char i,BackData=0;

unsigned char Address=0x00,ReadData=0x00;

while(1)

{ ResetI2C;

ReadData=ReadI2C(Address);

ReadData++;

Delay(5);

WriteI2C(Address,ReadData);

Delay(5);

Address++;Address++;

}

}

I2C 程序（已经验证 ）

#define _I2C_C_

#include "include_all.h"

/**************************

AT24C02????

//Author: Yuki

//Last modified : 2008-6-8

**************************/

#define NOPS();{_nop_();_nop_();_nop_();_nop_();_nop_();}

sbit SCL = P3^4; //pin16

sbit SDA = P3^5; //pin17

sbit TLED = P3^6;

unsigned char SystemError;

void Delay(int TIME)

{

while(TIME--);

}

//---------------------------------

// Function: void I2C_Start(void)

// Discrption:

//----------------------------------

void I2C_Start(void)

{

SDA = 1;

SCL = 1;

NOPS(); //Initial

SDA = 0;

NOPS(); //START

SCL = 0;

}

//---------------------------------

// Function: void I2C_Stop(void)

// Discrption:

//----------------------------------

void I2C_Stop(void)

{

SCL = 0;

SDA = 0;

NOPS(); //Initial

SCL = 1;

NOPS(); //STOP

SDA = 1;

}

//---------------------------------

// Function: void I2C_Start(void)

// Discrption:

//----------------------------------

WaitAck(void)

{

unsigned char errtime = 255;

SDA = 1;

NOPS();

SCL = 1;

NOPS();

SystemError = 0x10;

while(SDA)

{

errtime--;

if(!errtime)

{

I2C_Stop();

SystemError = 0x11;

return;

}

}

SCL = 0;

}

//---------------------------------

// Function: void SendAck(void)

// Discrption:

//----------------------------------

void SendAck(void)

{

SDA =0 ;

NOPS();

SCL = 1;

NOPS();

SCL = 0;

}

//---------------------------------

// Function: void SendNotAck(void)

// Discrption:

//----------------------------------

void SendNotAck(void)

{

SDA =1 ;

NOPS();

SCL = 1;

NOPS();

SCL = 0;

}

//-----------------------------------------------------

// Function: void I2CSendByte(unsigned char send_data)

// Discrption:

//-----------------------------------------------------

void I2CSendByte(unsigned char send_data)

{

unsigned char count = 8;

for(count = 0;count<8;count++)

{

SCL = 0;

_nop_();

SDA = (bit)(send_data & 0x80);

send_data <<= 1;

NOPS();

SCL = 1;

NOPS();

}

SCL = 0;

}

//-----------------------------------------------------

// Function: unsigned char I2CReceiveByte(void)

// Discrption:

//-----------------------------------------------------

unsigned char I2CReceiveByte(void)

{

unsigned char count = 8;

unsigned char dat = 0;

SDA = 1;

for(count = 0;count<8;count++)

{

dat <<= 1;

SCL = 0;

NOPS();

SCL = 1;

NOPS();

dat |= SDA;

}

SCL = 0;

return(dat);

}

//--------------------------------------------------------------------------

// Function: void WriteCharToChip(unsigned int address,unsigned char dat)

// Discrption:

//--------------------------------------------------------------------------

void WriteCharToChip(unsigned int address,unsigned char dat)

{

I2C_Start();

I2CSendByte(0xA0);

WaitAck();

I2CSendByte((char)(address)>>8); //????AT24C02,AT24C64,AT24C128,AT24C256??,??????????

Delay(300);

WaitAck();

I2CSendByte((char)(address));

WaitAck();

I2CSendByte(dat);

Delay(300);

WaitAck();

I2C_Stop();

}

//--------------------------------------------------------------------------

// Function: unsigned char ReadCharFromChip(unsigned int Address)

// Discrption:

//--------------------------------------------------------------------------

unsigned char ReadCharFromChip(unsigned int Address)

{

unsigned char recv_data;

I2C_Start();

I2CSendByte(0xA0);

WaitAck();

I2CSendByte((char)(Address>>8));//????AT24C02,AT24C64,AT24C128,AT24C256??,??????????

WaitAck();

I2CSendByte((char)(Address));

WaitAck();

I2C_Start();

I2CSendByte(0xA1);

WaitAck();

recv_data = I2CReceiveByte();

SendNotAck();

I2C_Stop();

return(recv_data);

}

main()

{

unsigned char Read_data;

for(;;)

{

WriteCharToChip(0x10,0xA3);

Read_data = ReadCharFromChip(0x10);

}

}