24C256发送后接受不到应答问题

只看该作者 · 2011-6-14 12:39

主设备：msp430F149  从设备24C256  上拉10K
程序从可用C51移植过来，调试N长时间就是检测不到ACK把SDA拉低。求大侠看看。
void IICStart(void)
{
  IIC_SDA_OUT;
  IIC_SCL_OUT;

  IIC_SCL_1;
  Delay_us(Delay_Time);
  IIC_SDA_1;
  Delay_us(Delay_Time);
  IIC_SDA_0;
  Delay_us(Delay_Time);
  IIC_SCL_0;
}

void IICStop(void)
{
IIC_SDA_OUT;
IIC_SCL_OUT;

IIC_SDA_0;
Delay_us(Delay_Time);
IIC_SCL_1;
Delay_us(Delay_Time);
IIC_SDA_1;

}

void IICNACK(void)
{
IIC_SDA_OUT;
IIC_SCL_OUT;

IIC_SDA_1;
Delay_us(Delay_Time);
IIC_SCL_1;
Delay_us(Delay_Time);
IIC_SCL_0;
Delay_us(Delay_Time);  //NACK
}

void IICWrite(unsigned char Datasend)
{
unsigned int i;

IIC_SDA_OUT;
IIC_SCL_OUT;

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

  if(Datasend&0x80)
  IIC_SDA_1;
  else
  IIC_SDA_0;
  Delay_us(Delay_Time);

  IIC_SCL_1;
  Delay_us(Delay_Time);
  IIC_SCL_0;
  Delay_us(Delay_Time);
  Datasend <<= 1;
}

/*IIC_SDA_1;  //可以试试直接IIC_SDA_0;Delay_us(Delay_Time);下面3句不用  相当于ACK
Delay_us(Delay_Time);
IIC_SDA_IN;                   //1
i = 100;                      //2
while((IIC_SDA_VAL) && (i>0)) i--; //3
IIC_SCL_1;
Delay_us(Delay_Time);
IIC_SCL_0;
Delay_us(Delay_Time);*/

IIC_SCL_1;                      //以下ACK检测
Delay_us(Delay_Time);
IIC_SDA_IN;
while(IIC_SDA_VAL);
IIC_SDA_OUT;
IIC_SCL_0;
Delay_us(Delay_Time);

}

unsigned char IICRead()
{
  unsigned char  i;
  unsigned char temp = 0;
  unsigned char Databit;

  IIC_SDA_IN;
  IIC_SCL_OUT;

  for(i=0;i<8;i++)
  {
Databit = IIC_SDA_VAL;
Delay_us(Delay_Time);
temp = (temp << 1) + Databit;
IIC_SCL_1;
Delay_us(Delay_Time);
IIC_SCL_0;
Delay_us(Delay_Time);
  }
return(temp);
}

unsigned char ReadByte(unsigned int addr,unsigned char a)  //a = 0 写X1227; a = 1 写 24C256； a = 2 写PCA9554A
{
  unsigned char temp;

  IICStart();

  if(a==0) IICWrite(0xde);
  else if(a==1) IICWrite(0xa0);  //调试先写0xae  256写0xa0
  else if(a==2) IICWrite(0x70);
  if((a==0)||(a==1))
  {
temp=(unsigned char)(addr>>8);
IICWrite(temp);
temp=(unsigned char)(addr&0xff);
IICWrite(temp);
  }
  else if(a==2)
  {
temp = (unsigned char)(addr&0xFF);
IICWrite(temp);
  }

IICStart();

if(a==0) IICWrite(0xdf);
else if(a==1) IICWrite(0xa1);//调试先写0xaf  256写0xa1
else if(a==2) IICWrite(0x71);
temp=IICRead();

//IICNACK();//也可以不发NACK 直接发停止
IICStop();
return(temp);
}

void WriteByte(unsigned int addr,unsigned char writedata,unsigned char a)
{
  unsigned char temp;

  IICStart();

  if(a==0) IICWrite(0xde);
  else if(a==1)IICWrite(0xa0);//调试先写0xae  256写0xa0
  else if(a==2)IICWrite(0x70);
  if((a==0)||(a==1))
  {
temp=(unsigned char)(addr>>8);
IICWrite(temp);
temp=(unsigned char)(addr&0xff);
IICWrite(temp);
IICWrite(writedata);
}
else if(a==2)
{
temp=(unsigned char)(addr&0xff);
IICWrite(temp);
IICWrite(writedata);
}

IICStop();
  // Delay_ms(10); //等待写周期
}

只看该作者 · 2011-6-14 12:42

补上宏定义
#define IIC_SCL_OUT       P6DIR |= BIT0 //P6.0
#define IIC_SCL_1       P6OUT |= BIT0
#define IIC_SCL_0       P6OUT &= (~BIT0)

#define IIC_SDA_IN       P6DIR &= (~BIT2) //P6.2
#define IIC_SDA_OUT       P6DIR |= BIT2
#define IIC_SDA_1       P6OUT |= BIT2
#define IIC_SDA_0       P6OUT &= (~BIT2)
#define IIC_SDA_VAL       ((P6IN >> 2) & 0x01)
我已吐血，顶

只看该作者 · 2011-6-14 14:59

顶，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，，

24C256发送后接受不到应答问题

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