[讨论] PIC16单片机写的一个24LC08的读写程序，为什么读出来是FF

liuqianxin 2015-3-13 11:21 楼主

#include
#define delay2408_TIME 2 //24C08的延迟时间
#define SCL1 RC3
#define SDA1 RC4
#define uchar unsigned char
#define uint  unsigned int
void I2cinit(void)
{
  //SSP1STAT=0x80;
  SSP1CON1=0x28;
  TRISC4=1; //SDA配置为输入；
  delay2408(delay2408_TIME);
  TRISC3=1; //SCL配置为输入；
  delay2408(delay2408_TIME);
}
void  delay2408(unsigned int t)  //24c08的延时函数,微妙延迟
{
  while(t--);

}

void I2C_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*/
  //SCL1=0;
  SDA1=1;
  delay2408(delay2408_TIME);
  SCL1=1;
  delay2408(delay2408_TIME);
  SDA1=0;
  delay2408(delay2408_TIME);
  //SCL1=0;
  //delay2408(delay2408_TIME);
}
void I2C_Stop(void)
{
/*终止I2C总线，当SCL为高电平时使SDA产生一个正跳变*/
  //SCL1=0;
  SDA1=0;
  delay2408(delay2408_TIME);
  SCL1=1;
  delay2408(delay2408_TIME);
  SDA1=1;
  delay2408(delay2408_TIME);
  //SCL1=0;
  //delay2408(delay2408_TIME);
}
void SEND_0(void)  /*SEND ACK*/
{
  /*发送0，在SCL为高电平时使SDA信号为低*/
  SDA1=0;
  delay2408(delay2408_TIME);
  SCL1=1;
  delay2408(delay2408_TIME);
  SCL1=0;
  delay2408(delay2408_TIME);
}
void SEND_1(void)
{
  /*发送1，在SCL为高电平时使SDA信号为高*/
  SDA1=1;
  delay2408(delay2408_TIME);
  SCL1=1;
  delay2408(delay2408_TIME);
  SCL1=0;
  delay2408(delay2408_TIME);
}
void Check_Acknowledge(void)
{
  /*发送完一个字节后检验设备的应答信号*/
  uchar a;
  //SCL1=0;
  //delay2408(delay2408_TIME);
  //SDA1=1;
  //delay2408(delay2408_TIME);
  SCL1=1;
  delay2408(delay2408_TIME);
  a=255;
  while(SDA1==1)
{
a--;
if(a==0)
   { SCL1=0;

   }
}
SCL1=0;
  delay2408(delay2408_TIME);
}
void WriteI2CByte(uchar b)
{
  /*向I2C总线写一个字节*/
unsigned char i;
i=0;
  for(i=0;i<8;i++)
   {
   if((b<       SEND_1();
      else
         SEND_0();
   }
SDA1=1;
delay2408(delay2408_TIME);
}
unsigned char ReadI2CByte(void)
{
/*从I2C总线读一个字节*/
unsigned char b=0,i;
for(i=0;i<8;i++)
   {
      SCL1=0;
      delay2408(delay2408_TIME);
      //SDA1=1;    /*释放总线*/
      //delay2408(4);
      SCL1=1;    /*接受总线*/
      delay2408(delay2408_TIME);
      if(SDA1==1)
      {
         b=b<<1;
         b=b|0x01;
         }
         else
            b=b<<1;
      delay2408(4);
      SCL1=0;
   }
  return b;
}
/******24c08的读写函数********************/
void Write_One_Byte(unsigned char addr,unsigned char thedata)
{
  I2C_Start();
  WriteI2CByte(0xa0);
  Check_Acknowledge(); //应答信号判断，这里应该需要确定它的应答信号
  WriteI2CByte(addr);
  Check_Acknowledge();
  WriteI2CByte(thedata);
  Check_Acknowledge();
  I2C_Stop();
  delay2408(2);
}
unsigned char Read_One_Byte(unsigned char addr)
{
  unsigned char mydata;
  /*read a byte from mem*/
  I2C_Start();
  WriteI2CByte(0xa0);
  Check_Acknowledge();
  WriteI2CByte(addr);
  Check_Acknowledge();
  I2C_Start();
  WriteI2CByte(0xa1);
  Check_Acknowledge();
  mydata=ReadI2CByte();
  delay2408(delay2408_TIME);
  I2C_Stop();
  return mydata;

}
void main()
{
  unsigned char data;
  data=0;
  Write_One_Byte(0x20,0x21);
  data=Read_One_Byte(0x20);
}