初学者编写了一个I2c—eeprom的程序·但是一直没有应答，实在想不出了·求帮助

gebbie · 发表于 2012-12-29 15:34:10

#include <MSP430G2553.h>

#define SDA_1    P1OUT |= BIT7
#define SDA_0    P1OUT &=~ BIT7
#define SCL_1    P1OUT |= BIT6
#define SCL_0    P1OUT &=~ BIT6
#define SDA_out P1OUT |= BIT7
#define SDA_in   P1OUT &=~ BIT7
unsigned char Readword[12];
void init_clk(void)
{
    unsigned char j;
    do
    {
        IFG1 &=~ OFIFG;
        for( j=10 ; j>0 ; j--)
        {
            _NOP();
        }
    }
   while((IFG1&OFIFG)!=0);
   P1DIR |= BIT6+BIT7;
   P3DIR |= BIT5;
   P3OUT &=~ BIT5;
}
void Delay(void)        //Delay
{
unsigned char t;
for(t=0;t<15;t++)
    _NOP();
}
void Long_Delay(void)        //Delay
{
unsigned char t;
for(t=0;t<200;t++)
    _NOP();
}
void Start(void)         //Start
{
SDA_out;
SCL_1;
_NOP();
   SDA_1;
Delay();
   SDA_0;
Delay();
SCL_0;
Delay();
}
void Stop(void)       //Stop
{
SDA_0;
Delay();
SCL_1;
Delay();
SDA_1;
Delay();
}
void ACK(void)        //ACK
{
SDA_0;
SCL_0;
Delay();
SCL_1;
Delay();
SCL_0;
Delay();
SDA_1;
Delay();
}
void NACK(void)      // NOT ACK
{
SDA_1;
Delay();
SCL_1;
Delay();
SCL_0;
Delay();
SDA_0;
Delay();
}
void Write1(void)     //Write a bit : 1
{
SDA_1;
Delay();
SCL_1;
Delay();
SCL_0;
Delay();
}
void Write0(void)             //Write a bit : 0
{
SDA_0;
Delay();
SCL_1;
Delay();
SCL_0;
Delay();
}
void Writebyte(unsigned char Wchar)    //写一个字Wchar
{
unsigned char   i;
for(i=0;i<8;i++)
{
    if(Wchar&0x80) Write1();
    else Write0();
    Wchar<<=1;
}
SDA_1;
Delay();
}

unsigned char CheckACK(void) //receive ACK
{
unsigned char flag;
//SDA_1;
Delay();
SCL_1;
Delay();
SDA_in;
_NOP();_NOP();
flag = P1IN&BIT7 ;        //read SDA
SCL_0;
Delay();
SDA_out;
if(flag) return 0;
   else return 1;
}
unsigned char Readbyte(void)
{
unsigned char rchar=0 ,i,flag;
   SCL_0;
   Delay();
for(i=0;i<8;i++)
{
    SDA_in;
    Delay();
    SCL_1;
    Delay();
    flag=P1IN&BIT7;
    rchar<<=1;
    if(flag) rchar |= 0x01;
    _NOP();
   // SDA_out;
   // Delay();
    SCL_0;
    Delay();
}
     SCL_0;
     Delay();
return rchar;
}
void WriteNbyte(unsigned char address,unsigned char dataaddr,unsigned char *buff,unsigned char n)
{
unsigned char i;
      Start();
     Writebyte(address);    //find eeprom
     if(!CheckACK())
       {Stop();return ;}
      Writebyte(dataaddr);   //find unit address
     if(!CheckACK())
        {Stop();return ;}
      for(i=0;i<n;i++)
        {
            Writebyte(buff);
            if(!CheckACK())
            {Stop();return ;}
        }
     Stop();
     Delay();
}
void ReadNbyte(unsigned char address,unsigned char dataaddr,unsigned int n)
{
    unsigned char i;
      Start();
     Writebyte(address);    //find eeprom
     if(!CheckACK())
       {Stop();return ;}
     Writebyte(dataaddr);   //find unit address
     if(!CheckACK())
        {Stop();return ;}
     Start();
     Writebyte(0xaf);     //read
     if(!CheckACK())
        {Stop();return ;}
   for(i=0;i<n;i++)
   {
    Readword=Readbyte();
    ACK();
   }
    Stop();
    Delay();
}
void main(void)
{
    unsigned char write[9],i;
    for(i=0; i<8; i++){
    write =49+i;
    }

    WDTCTL = WDTPW + WDTHOLD;
    init_clk();
   // P1SEL = 0xc0;              P1.6,7= SCL&SDA
     while(1)
     {
     //write
     WriteNbyte(0xae,0x00,write,2);
     Long_Delay();
     //read
     ReadNbyte(0xae,0x00,2);
     Long_Delay();
     Long_Delay();
     }
}

gebbie · 发表于 2012-12-29 15:36:14

单片机用的MSP430g2553,求帮忙·

gebbie · 发表于 2012-12-29 15:44:31

无应答的话与程序的关系不太大吧·可是硬件的问题我都想了一遍了，实在想不出了

正点原子 · 发表于 2012-12-29 16:56:23

很大，你的430，IO方向不用配置的么？
IIC的SDA，输出地址和命令的时候，要配置为输出模式。
读取数据的时候，又要配置为输入模式的。

gebbie · 发表于 2012-12-29 18:55:45

回复【4楼】正点原子:
---------------------------------
谢谢你啊，我试试，我只是在开始的时候配置了DIR--P1DIR |= BIT6+BIT7;不明白这一点，我去调试看看波形。

艾科 · 发表于 2012-12-29 19:23:16

回复【楼主位】gebbie:
---------------------------------
设置IO口方向是
#define SDA_out

1DIR |= BIT7
#define SDA_in

1DIR &=~ BIT7，延时用比较精准的延时，
例如下面这个，好用，而且准确，
#define CPU_F ((double) 8000000.0)//当前CPU主频
#define delay_us(x) __delay_cycles((long)(CPU_F*(double)x/1000000.0))
#define delay_ms(x) __delay_cycles((long)(CPU_F*(double)x/1000.0))，
然后看时序图。