51--i2c.c

51 i2c 51 i2c 51 i2c 51 i2c 51 i2c

void IIC_Start(void); 
void IIC_Stop(void); 
void SEND_0(void); 
void SEND_1(void); 
bit Check_Acknowledge(void); 
void Write_Byte(uchar b)reentrant; 
bit Write_N_Bytes(uchar *buffer,uchar n)reentrant; 
bit Read_N_Bytes(uchar SlaveAdr,uchar n,uchar *buffer); 
uchar Read_Byte(void)reentrant; 
*/ 

#include<string.h> 
#include<reg52.h> 
#include<intrins.h> 
#include"aiic_51.h" 

sbit SCL=P1^6; 
sbit SDA=P1^7; 

void DELAY(uint t) 
{ 
while(t!=0) 
t--; 
} 

void IIC_Start(void) 
{ 
//启动I2C总线的函数，当SCL为高电平时使SDA产生一个负跳变 
SDA=1; 
SCL=1; 
DELAY(DELAY_TIME); 
SDA=0; 
DELAY(DELAY_TIME); 
SCL=0; 
DELAY(DELAY_TIME); 
} 

void IIC_Stop(void) 
{ 
//终止I2C总线，当SCL为高电平时使SDA产生一个正跳变 
SDA=0; 
SCL=1; 
DELAY(DELAY_TIME); 
SDA=1; 
DELAY(DELAY_TIME); 
SCL=0; 
DELAY(DELAY_TIME); 
} 

void SEND_0(void) 
{ 
//发送0，在SCL为高电平时使SDA信号为低 
SDA=0; 
SCL=1; 
DELAY(DELAY_TIME); 
SCL=0; 
DELAY(DELAY_TIME); 
} 

void SEND_1(void) 
{ 
//发送1，在SCL为高电平时使SDA信号为高 
SDA=1; 
SCL=1; 
DELAY(DELAY_TIME); 
SCL=0; 
DELAY(DELAY_TIME); 
} 

bit Check_Acknowledge(void) 
{ 
//发送完一个字节后检验设备的应答信号 
SDA=1; 
SCL=1; 
DELAY(DELAY_TIME/2); 
F0=SDA; 
DELAY(DELAY_TIME/2); 
SCL=0; 
DELAY(DELAY_TIME); 
if(F0==1) 
return FALSE; 
return TRUE; 
} 

void Write_Byte(uchar b)reentrant 
{ 
//向IIC总线写一个字节 
uchar i; 
for(i=0;i<8;i++) 
if((b<<i)&0x80) 
SEND_1(); 
else 
SEND_0(); 
} 

bit Write_N_Bytes(uchar *buffer,uchar n)reentrant 
{ 
//向I2C总线写n个字节 
uchar i; 
IIC_Start(); 

for(i=0;i<n;i++) 
{ 
Write_Byte(buffer[i]); 
if(!Check_Acknowledge()) 
{ 
IIC_Stop(); 
return(i==n); 
} 
} 

IIC_Stop(); 
return TRUE; 
} 

uchar Read_Byte(void)reentrant 
{ 
//从I2C总线读一个字节 
uchar b=0,i; 
for(i=0;i<8;i++) 
{ 
SDA=1; //释放总线 
SCL=1; //接受数据 
DELAY(10); 
F0=SDA; 
DELAY(10); 
SCL=0; 
if(F0==1) 
{ 
b=b<<1; 
b=b|0x01; 
} 
else 
b=b<<1; 
} 
return b; 
} 

bit Read_N_Bytes(uchar SlaveAdr,uchar n,uchar *buffer) 
{ 
//从I2C总线读n个字节 
uchar i; 
IIC_Start(); 
Write_Byte(SlaveAdr); //向总线发送接收器地址 
if(!Check_Acknowledge()) //等待接收器应答信号 
return FALSE; 
for(i=0;i<n;i++) 
{ 
buffer[i]=Read_Byte(); 
if(i!=n) 
SEND_0(); //发送应答 
else 
SEND_1(); //发送非应答 
} 
IIC_Stop(); 
return TRUE; 
}