关于单总线通讯问题

只看该作者 · 2011-6-3 22:21

最近一直在写单总线和DS1990 iButton卡通讯的问题.在网上参考了很多例子都没有解决,烦死我了,在这里想请教一下各位,我的程序到底哪里出错了(本人初学,暂时先读出序列号前8位,看看到底怎么和IB卡通讯的.)拜托各位帮下忙.感激不尽啊.(使用ATMEGA48,内部8M晶振)#include<avr/io.h>
#include<util/delay.h>
#include<yanshi.h>
#include<avr/interrupt.h>
#define uchar unsigned char
#define uint unsigned int
#define set1(a,b) a|=(1<<b)
#define set0(a,b) a&=~(1<<b)
void w1_init(void) //复位
{

DDRD=set0(DDRD,PD2);

while(PIND&0X04);

DDRD=set1(DDRD,PD2);

PORTD=set1(PORTD,PD2);

_delay_us(1);

PORTD=set0(PORTD,PD2);//

_delay_us(550);//延时至少480us

DDRD=set0(DDRD,PD2);//释放数据线

_delay_us(60);//延时大于60us

while(PIND&0X04);

_delay_us(500);//延时保证时序完整性

DDRD=set1(DDRD,PD2);

PORTD=set1(PORTD,PD2);

PORTD=set0(PORTD,PD2);
}
void write1(void)
{

DDRD=set1(DDRD,PD2);//拉成低电平

PORTD=set1(PORTD,PD2);

_delay_us(1);

PORTD=set0(PORTD,PD2);

_delay_us(5);//保持至少1us
  DDRD=set0(DDRD,PD2);//释放数据线

_delay_us(65);//等待足够时间使da1990采样数据线

DDRD=set1(DDRD,PD2);//拉成低电平

PORTD=set1(PORTD,PD2);

_delay_us(1);

PORTD=set0(PORTD,PD2);
}
void write0(void)
{

DDRD=set1(DDRD,PD2);//拉成低电平

PORTD=set1(PORTD,PD2);

_delay_us(1);

PORTD=set0(PORTD,PD2);

_delay_us(65);//等待足够时间使ds1990采样数据线

DDRD=set1(DDRD,PD2);//拉成低电平

PORTD=set1(PORTD,PD2);

_delay_us(1);

PORTD=set0(PORTD,PD2);

}
void write_ds1990(uchar command)
{

uchar n=0;

for(n=0;n<8;n++)

{

if(command&0x01)

write1();

else

write0();

command>>=1;

_delay_us(2);

}
}

uchar ds1990_bitread(void)
{

DDRD=set1(DDRD,PD2);

PORTD=set1(PORTD,PD2);

_delay_us(1);

PORTD=set0(PORTD,PD2);

_delay_us(2);//保持至少1us

DDRD=set0(DDRD,PD2);//释放数据线

_delay_us(8);//延时使主机再15us的后阶段读取数据线

if(PIND&0x04)

{

return 1;

}

else

{

return 0;

}
  DDRD=(DDRD,PD2);

PORTD=set1(PORTD,PD2);

PORTD=set0(PORTD,PD2);

}

uchar ds1990_byteread(void)
{

uchar n,Readback=0;

for(n=0;n<8;n++)

{

Readback>>=1;

if(ds1990_bitread())

Readback|=0x80;

_delay_us(61);

}

return Readback;
}

uchar main(void)
{

while(1)

{
      sei();

uchar a;

uchar b;

      w1_init();
      write_ds1990(0x33);
      DDRD=set1(DDRD,PD0);
      b=ds1990_byteread();
for(a=0;a<8;a++)
{

if((b&0x01))

{

PORTD=set1(PORTD,PD0);

delay_nms(1000);

PORTD=set0(PORTD,PD0);

delay_nms(1000);

}

else

{

PORTD=set1(PORTD,PD0);

  delay_nms(100);

  PORTD=set0(PORTD,PD0);

  delay_nms(100);
                        PORTD=set1(PORTD,PD0);

  delay_nms(100);

  PORTD=set0(PORTD,PD0);

  delay_nms(1000);

}

b>>=1;

}
}
}