武林教你学PIC32（十八）单总线DS18B20温度传感器

简单介绍下DS18B20,它是独特的单线接口，仅需一个端口进行通讯9~12位的分辨率可调（RS）测温范围为-55°C~+125°C;测量范围在-10°C ~+85°C精度为±0.5°C可设置报警温度存储于EEPROM，掉电保护数据不丢适用电压3~5.5V

下面介绍我封装好的函数,已经测试可以使用，需要注意的是PORTReadBits，需要根据实际端口相应地移位

DS18B20.H:

#ifndef _DS18B20_H_

#define _DS18B20_H_

#include

#define DQ_PORTIOPORT_D//设置DQ引脚

#define DQ_PINBIT_14

#define SET_OP_1WIREPORTSetBits(DQ_PORT, DQ_PIN)

#define CLR_OP_1WIREPORTClearBits(DQ_PORT, DQ_PIN)

#define SET_DIR_1WIREPORTSetPinsDigitalOut(DQ_PORT, DQ_PIN)

#define CLR_DIR_1WIREPORTSetPinsDigitalIn(DQ_PORT, DQ_PIN)

#define CHECK_IP_1WIREPORTReadBits(DQ_PORT, DQ_PIN)>>14

extern void delay_us(unsigned int num);

extern void delay_ms(unsigned int num);

float gettemp(void);//读取温度值

#endif

DS18B20.C

#include "ds18b20.h"

void init_1820()

{

SET_DIR_1WIRE; //设置PC2为输出

SET_OP_1WIRE;

CLR_OP_1WIRE;

delay_us(480);//480us以上

SET_OP_1WIRE;

CLR_DIR_1WIRE;

delay_us(20);//15~60us

while(CHECK_IP_1WIRE);

SET_DIR_1WIRE;

SET_OP_1WIRE;

delay_us(140);//60~240us

}

void write_1820(unsigned char x)

{

unsigned char m;

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

{

CLR_OP_1WIRE;

if(x&(1<

SET_OP_1WIRE;

else

{CLR_OP_1WIRE;}

delay_us(40);//15~60us

SET_OP_1WIRE;

}

SET_OP_1WIRE;

}

unsigned char read_1820()

{

unsigned char temp,k,n;

temp=0;

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

{

CLR_OP_1WIRE;

SET_OP_1WIRE;

CLR_DIR_1WIRE;

k=(CHECK_IP_1WIRE);//读数据,从低位开始

if(k)

temp|=(1<

else

temp&=~(1<

delay_us(50); //60~120us

SET_DIR_1WIRE;

}

return (temp);

}

float gettemp()//读取温度值

{

unsigned char temh,teml;

unsigned int temp;

float value;

init_1820();//复位18b20

write_1820(0xcc);//发出转换命令

write_1820(0x44);

//delay_nms(800);//不延时也好使，不知道怎么回事！

init_1820();

write_1820(0xcc);//发出读命令

write_1820(0xbe);

teml=read_1820();//读数据

temh=read_1820();

temp=temh;

temp<<=8;

temp|=teml;

value=temp*0.0625;

return value;

}