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利用8051实现I2C主机功能

已有 3130 次阅读| 2011-6-13 20:25

根据I2C协议，本人写的符合协议的代码，已经在8051上面挂了一个I2C从机，测试通过，使用逻辑分析仪来分析数据，结果表明符合，符合协议内容。。贴出代码，供大家交流，共同进步。。。

适合于普通模式，主机的时钟频率大概在120K左右。。

因为是C语言，对时间的控制不是很精确。。。

#include "reg51.h"

#include "intrins.h"

sbit SCL= P1^7;

sbit SDA= P1^6;

void Start_I2C(void)

{

SDA=1;

SCL=1;

_nop_();

SDA=0;

_nop_();

SCL=0;

}

void Stop_I2C (void)

{

SDA=0;

SCL=1;

_nop_();

SDA=1;

_nop_();

}

bit SendAck(void)

{

SDA=0;

_nop_();

SCL=1;

_nop_();

SCL=0;

return(1);

}

bit DetectAck(void)

{

unsigned char errtime = 255;

SDA = 1;

SCL = 1;

_nop_();

while(SDA)

{

errtime--;

if(errtime==0)

{

Stop_I2C();

return(0);

}

SCL = 0;

_nop_();

return(1);

}

void Send_I2C (unsigned char ch)

{

unsigned char i;

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

{

SCL=0;

_nop_();

SDA=(ch&0x80);

ch<<=1;

_nop_();

SCL=1;

_nop_();

}

SCL=0;

}

unsigned char Receive_I2C(void)

{

unsigned char i,data_in=0;

SDA=1;

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

{

data_in<<=1;

SCL=0;

_nop_();

SCL=1;

_nop_();

data_in|=SDA;

}

SCL=0;

return data_in;

}

void write(unsigned char regaddress,unsigned char data0)

{

Start_I2C();

Send_I2C(0x98);

if(DetectAck())

{

Send_I2C(regaddress);

if(DetectAck())

{

Send_I2C(data0);

if(DetectAck())

Stop_I2C();

}

else

Stop_I2C();

}

else

Stop_I2C();

}

void read(unsigned char regaddress)

{

Start_I2C();

Send_I2C(0x98);

if(DetectAck())

{

Send_I2C(regaddress);

if(DetectAck())

{

Start_I2C();

Send_I2C(0x99);

if(DetectAck())

{

P2=Receive_I2C();

Stop_I2C();

}

else Stop_I2C();

}

else Stop_I2C();

}

else

Stop_I2C();

}

void write_read(unsigned char regaddress,unsigned char data0)

{

write(regaddress, data0);

read(regaddress);

}

void doublebyte_write_read(unsigned char baseaddress,unsigned char data1,unsigned char data2)

{

Start_I2C();

Send_I2C(0x98);

if(DetectAck())

{

Send_I2C(baseaddress);

if(DetectAck())

{

Send_I2C(data1);

if(DetectAck())

{

Send_I2C(data2);

if(DetectAck())

Stop_I2C();

else Stop_I2C();

}

else Stop_I2C();

}

else Stop_I2C();

}

else

Stop_I2C();

Start_I2C();

Send_I2C(0x98);

if(DetectAck())

{

Send_I2C(baseaddress);

if(DetectAck())

{

Start_I2C();

Send_I2C(0x99);

if(DetectAck())

{

P2=Receive_I2C();

SendAck();

P2=Receive_I2C();

Stop_I2C();

}

else Stop_I2C();

}

else Stop_I2C();

}

else Stop_I2C();

}

void main()

{

write_read(0x2D,0xD2);

write_read(0x2E,0xE2);

read(0x3C)；

write_read(0x3C,0xCC);

read(0x01);

read(0x02);

doublebyte_write_read(0x01,0x11,0x22);

}

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