PIC16F877A例程---DS18B20

void WRITE_LCD_CMD(char cmd)

{

LCD1602_BUSY();

TRISB & =0XF8;

TRISD=0;

LCDDATA=cmd;

LCDRS=0;

LCDRW=0;

LCDE=0;

asm("NOP");

asm("NOP");

LCDE=1;

}

void LCD1602_INIT(void)

{

LCD1602_BUSY();

TRISB &= 0XF8;

TRISD=0;

WRITE_LCD_CMD(CLRLCD);

WRITE_LCD_CMD(LCDMOD);

WRITE_LCD_CMD(TURNON);

WRITE_LCD_CMD(CURMODE);

LCD_Display_location (0,0);

}

void DS18B20_INIT()

{

TRIS_B20=0;

DS18B20=0;

US_delay(20);

TRIS_B20=1;

US_delay(10);

}

void WRITE_DS18B20_CMD(char cmd)

{

char tmp;

char i;

TRIS_B20=0;

for(tmp=8;tmp>0;tmp--)

{

TRIS_B20=0;

DS18B20= 0;

asm ("NOP");

asm ("NOP");

asm ("NOP");

asm ("NOP");

asm ("NOP");

if (cmd & 0x01)

{

TRIS_B20=1;

US_delay(1);

for (i=5;i>0;i--);

}

else

{

DS18B20=0 ;

US_delay(1);

for (i=5;i>0;i--);

TRIS_B20=1;

}

cmd=cmd/2;

}

}

float READ_DS18B20 ()

{

char tmp=0x01;

float t;

union

{

char c[2];

int x;

}temp;

temp.x=0;

while (tmp)

{ // read first 8 bits

TRIS_B20=0;

DS18B20=0;

asm("NOP");

TRIS_B20=1;

if (DS18B20)

temp.c[0] |= tmp;

tmp=tmp<<1;

US_delay(2);

}

tmp=1;

while (tmp)

{ // read first 8 bits

TRIS_B20=0;

DS18B20=0;

asm("NOP");

TRIS_B20=1; // release the bus

asm("NOP");

if (DS18B20) // "1" presented

temp.c[1] |= tmp;

tmp=tmp<<1;

US_delay(2);

}

t=((float) temp.x)/16.0 ;

return t;

}

void itoa10(unsigned char *buf, int i)

{

unsigned int rem;

unsigned char *s,length=0;

s = buf;

if (i == 0)

*s++ = 0;

else

{

if (i < 0)

{

*buf++ = -;

s = buf;

i = -i;

}

while (i)

{

++length;

rem = i % 10;

*s++ = rem + 0;

i /= 10;

}

for(rem=0; ((unsigned char)rem)

{

*(buf+length) = *(buf+((unsigned char)rem));

*(buf+((unsigned char)rem)) = *(buf+(length-((unsigned char)rem)-1));

*(buf+(length-((unsigned char)rem)-1)) = *(buf+length);

}

}

*s=0;

}

void US_delay( int i)

{

unsigned char j;

while(i--)

{

j=3;

while(j--);

}

}