写数据总是显示失败

1万 · 2016-3-26 21:45

msp430向24c02里写数据，总是显示失败

/**************************************
程序功能：将数据存入24c08，然后用led显示存入的数据
*/
#include<msp430x14x.h>
#define uchar unsigned char
#define uint unsigned int

#define SCL_H P1OUT |= BIT2    //高低电平宏定义
#define SCL_L P1OUT &= ~BIT2
#define SDA_H P1OUT |= BIT3
#define SDA_L P1OUT &= ~BIT3

#define SCL_OUT P1DIR |= BIT2 //将P1.2口(SCL)设为输出状态
#define SDA_OUT P1DIR |= BIT3 //将P1.3口(SDA)设为输出状态
#define SDA_IN P1DIR &= ~BIT3 //将P1.3口设为输入状态，判断SDA高低电平
#define SDA_T (P1IN & BIT3)    //用于数据线(SDA)的检测

void delay(uchar n)          //短暂延时函数，用于电平延时
{
  uchar i,j;
  for(i=n;i>0;i--)
for(j=0;j<5;j++);
}

void io_init()       //用于显示
{
  P2DIR = 0XFF;    //用于led显示
}

void iic_init()    //iic总线初始化
{
  SCL_OUT;          //将P1.2口(SCL)设为输出状态
  SDA_OUT;
  delay(1);

  SCL_H;
  delay(1);
  SDA_H;
  delay(1);
}

void start()
{
  SDA_OUT;
  delay(1);

  SCL_H;
  delay(1);
  SDA_H;
  delay(1);
  SDA_L;
  delay(1);
}

void stop()
{
  SDA_OUT;
  delay(1);

  SCL_H;
  delay(1);
  SDA_L;
  delay(1);
  SDA_H;
  delay(1);
}

void respon()                //可能有问题，简化了应答机制
{
  uchar i=0;
  SDA_IN;                   //输入，用于读数据

  SCL_H;                   //高电平时
  delay(1);
  while((SDA_T==1)&&(i<252)) //等待应答，即SDA拉低0
  {
i++;
  }
}

void writebyte(uchar data)    //从最高位开始传送
{
  uchar i;
  SDA_OUT;

  for(i=0; i<8; i++)
  {
SCL_L;
delay(1);
if((data&0x80)==0x80)
   SDA_H;
else
   SDA_L;
delay(1);

SCL_H;
delay(1);
data = data << 1;    //data左移7次即可，第8次没给sda
  }
}

uchar readbyte()             //从最高位开始读
{
  uchar i,temp=0;
  SDA_IN;                   //输入，用于读数据
  delay(1);

  for(i=0; i<8; i++)
  {
SCL_L;                   //允许数据变化
delay(1);
SCL_H;                   //停止数据变化
delay(1);
temp = (temp<<1)|SDA_T;
delay(1);
  }
  return temp;
}

void write_24c08(uchar add,uchar data)
{
  start();
  writebyte(0xa0); //单字节写入
  respon();
  writebyte(add);
  respon();
  writebyte(data);
  respon();
  stop();
}

uchar read_24c08(uchar add)
{
  uchar data;
  start();
  writebyte(0xa0); //单字节写入
  respon();
  writebyte(add);
  respon();

  start();
  writebyte(0xa1); //单字节读
  respon();
  data = readbyte();
  stop();
  return data;
}

void main(void)
{
  uchar data;          //用于存放读出的数据
  WDTCTL = WDTPW + WDTHOLD;
  io_init();
  iic_init();

  write_24c08(8,0x55); //随便写入一个数据
  data = read_24c08(8);

  P2OUT = data;          //用led显示
  while(1);
}