18b20.c

18b20显示程序,动态显示,调试通过.

/*****************************************/
/*		 */
/*****************************************/

#include <reg51.h>		// 引用标准库的头文件
#include <absacc.h>
#include <stdio.h>
#include <math.h>

#define uchar unsigned char 
#define uint unsigned int 

#define skrom  0xcc         
#define convt  0x44
#define rdpad  0xbe
uchar  playcode[]={0x40,0x4f,0x24,0x06,0x0b,0x12,0x10,0x47,0x00,0x02};

uchar tplsb,tpmsb,temp,j;		// 温度值低位、高位字节 

sbit DQ = P0^7;			// 数据通信线DQ

// DELAY - with an 11.059MHz crystal
// Calling the routine takes about 24μs, and then
// each count takes another 16us//
void delay (int us)
{
	int s;
	for (s = 0; s < us; s++);
}			        
unsigned char ow_reset(void)
{
	unsigned char presence;
	DQ = 0; //pull DQ line low
	delay(29); // leave it low for 480μ
	DQ = 1; // allow line to return high
	delay(3); // wait for presence
	presence = DQ; // get presence signal
	delay(25); // wait for end of timeslot
	return(presence); // presence signal returned
} // presence = 0, no part = 1
unsigned char read_bit(void)
{
	unsigned char i;
	DQ = 0; // pull DQ low to start timeslot
	DQ = 1; // then return high
	for (i = 0; i < 3; i++); // delay 15μs from	start of timeslot
	return(DQ); // return value of DQ line
}
void write_bit(char bitval)
{
	DQ = 0; // pull DQ low to start timeslot
	if(bitval==1) DQ =1; // return DQ high if write 1
	delay(5);// hold value for remainder of timeslot
	DQ = 1;
}// Delay provides 16μs per loop, plus 24μs
//Therefore, delay(5) = 104μs
unsigned char read_byte(void)
{
	unsigned char i;
	unsigned char value = 0;
	for (i = 0; i < 8; i++)
		{
		if(read_bit()) value|=0x01<<i;
		// reads byte in, one byte at a time and then
		// shifts it left
		delay(6); // wait for rest of timeslot
		}
	return(value);
}
void write_byte(char val)
{
	unsigned char i;
	unsigned char temp;
	for (i = 0; i < 8; i++) // writes byte, one bit at a time
		{
		temp = val>>i; // shifts val right ‘i’ spaces
		temp &= 0x01; // copy that bit to temp
		write_bit(temp); // write bit in temp into
		}
	delay(5);
}
main()
{
	while(1)
	{
		ow_reset();
		write_byte(skrom);
		write_byte(convt);         
		//delay(30000);delay(20000);
		for(j=0;j<20;j++)
	    { P2=0xf7;
		temp=tpmsb/10;   //十位显示
	    P1=playcode[temp]; 
        delay(800);  

	    P2=0xfb;      //个位显示
	    temp=tpmsb%10;
   		P1=playcode[temp];
	    delay(800); 
	    P2=0xff;
		}
		ow_reset();
		write_byte(skrom);
		write_byte(rdpad); 
		tplsb=read_byte();
		tpmsb=read_byte();
		
		tpmsb=(tpmsb<<4)|(tplsb>>4);
		P2=0xf7;
	    temp=tpmsb/10;   //十位显示
	    P1=playcode[temp]; 
        delay(800);  

	    P2=0xfb;      //个位显示
	    temp=tpmsb%10;
   		P1=playcode[temp];
	    delay(800); 
	    P2=0xff;
    
	}

}