iic读取总是返回0xff，请高手帮忙看看。谢谢

可以试试这个，IIC 的时序要正确 我不知道你是否按照时序图写了

#define I2C_DELAY; _nop_();_nop_();_nop_();_nop_();_nop_(); // >=4.7uS

//----------------------------------------------------------------
// delay 100us
//----------------------------------------------------------------
void mDelay(INT8U k)
{
INT16U i ;

for(; k>0; k--)
{
for(i=0; i<93; i++)
;
}
}



//----------------------------------------------------------------
//OK
//----------------------------------------------------------------
void I2C_Start(void)
{
SDA = 1;
I2C_DELAY;

SCL = 1;
I2C_DELAY;

SDA = 0;
I2C_DELAY;
I2C_DELAY;
}



//----------------------------------------------------------------
//OK
//----------------------------------------------------------------
void I2C_Stop(void)
{
SDA = 0 ;
I2C_DELAY;

SCL = 1 ;
I2C_DELAY;

SDA = 1 ;
I2C_DELAY;
I2C_DELAY;
}



//----------------------------------------------------------------
//
//----------------------------------------------------------------
void sendAck(void)
{
SCL = 0;
I2C_DELAY;

SDA = 0;
I2C_DELAY;

SCL = 1;
I2C_DELAY;

}


//----------------------------------------------------------------
//
//----------------------------------------------------------------
void sendNoAck(void)
{
SCL = 0;
I2C_DELAY;

SDA = 1;
I2C_DELAY;

SCL = 1;
I2C_DELAY;

}


//----------------------------------------------------------------
// 0 = noACK; 1 = ACK ;
//----------------------------------------------------------------
bit checkAck()
{
bit tempbit;
/*发送完一个字节后检验设备的应答信号*/
SDA = 1;
I2C_DELAY;

SCL = 0;
I2C_DELAY;

tempbit = SDA;

SCL = 1;
I2C_DELAY;

if(tempbit==1)
{
return 0; //noACK
}
else
{
return 1; //ACK
}
}



//----------------------------------------------------------------
//OK
// a positive clock edge clock a bit into the ROM
//----------------------------------------------------------------
void writeByte(INT8U datum)
{
INT8U bitCnt = 0 ;

for(bitCnt=0; bitCnt<8; bitCnt++)
{
SCL = 0 ;
I2C_DELAY;

if ((datum&0x80) == 0x80) //if the MSb is 1
SDA = 1 ;
else
SDA = 0 ;
I2C_DELAY;

SCL = 1 ;
I2C_DELAY;

datum<<=1 ;
}

}



//----------------------------------------------------------------
//OK
//----------------------------------------------------------------
INT8U readByte(void)
{
bit tempbit = 1 ;
INT8U temp = 0 ;
INT8U bitCnt ;

SDA = 1 ; // release the bus,ready to receive byte??????????????
I2C_DELAY;

for(bitCnt=0; bitCnt<8; bitCnt++)
{
SCL = 0; //?????????????????????????huan???????????????
I2C_DELAY;

tempbit = SDA ;
if (tempbit)
temp |= 0x01 ;
else
temp &= 0xfe ;

SCL = 1 ;
I2C_DELAY;

if(bitCnt<7)
temp <<= 1 ;

}

return(temp) ;
}



/*~~~~~~~~~~~~~~~~~~~~~~~ API ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/

/*-----------------------------------------------------------------
write some bytes to sequential address
-----------------------------------------------------------------*/
void writeToROM(INT8U datum[], INT8U address, INT8U num)
{
bit tempbit ;
INT8U i ;
INT8U *datum_P ;
datum_P = datum ;

I2C_Start() ;

writeByte(0xa0) ;
tempbit = checkAck();

writeByte(address) ;
tempbit = checkAck();

for(i=0; i
{
writeByte(*(datum_P+i)) ;


if(!checkAck())
{
I2C_Stop() ;
mDelay(100) ;
}
}

I2C_Stop() ;
}



/*-----------------------------------------------------------------
read some bytes from ROM`s sequential address
-----------------------------------------------------------------*/
void readFromROM(INT8U datum[], INT8U address, INT8U num)
{
bit tempbit ;
INT8U i ;
INT8U *datum_P ;

datum_P = datum;

I2C_Start() ;

writeByte(0xa0) ;
tempbit = checkAck();

writeByte(address) ;
tempbit = checkAck();

I2C_Start() ;
writeByte(0xa1) ;
tempbit = checkAck();

for(i=0; i
{
*(datum_P+i) = readByte() ;

if(i!=num-1)
{
sendAck() ;
}
else
{
sendNoAck() ;
}
}

I2C_Stop() ;
}



/*-----------------------------------------------------------------
wirte one byte to ROM --random write
-----------------------------------------------------------------*/
void writeOneByte(INT8U addr, INT8U datum)
{
bit tempbit ;
/*write a byte to mem*/

I2C_Start();

writeByte(0xa0);
tempbit = checkAck();

writeByte(addr); /*address*/
tempbit = checkAck();

writeByte(datum); /*the data*/

tempbit = checkAck();

I2C_Stop();
mDelay(100) ;

}



/*-----------------------------------------------------------------
read one byte from rom --random read
-----------------------------------------------------------------*/
INT8U readOneByte(INT8U addr)
{
bit tempbit = 1;
INT8U mydata;
/*read a byte from mem*/

I2C_Start();

writeByte(0xa0);
tempbit = checkAck();

writeByte(addr); /*address*/
tempbit = checkAck();

I2C_Start();

writeByte(0xa1);
tempbit = checkAck();

mydata = readByte();
tempbit = checkAck();

return (mydata) ;

I2C_Stop();
}

遇到同样问题了，楼主，请问你解决了么

没有读出来，没有写进去

楼主我用你的代码显示到数码管上表明已经写进去和读出来了
你源代码中哪里可以显示读出来？？？