DS18B20驱动时序可参考https://mbb.eet-china.com/forum/topic/86899_1_1.html，这里不再赘述。
新建工程，添加测温代码如下：
#define DS18B20_DQ GET_PIN(E, 7) //DQ数据线//复位DS18B20 void DS18B20_Rst(void) { rt_pin_mode(DS18B20_DQ, PIN_MODE_OUTPUT); //输出模式 rt_pin_write(DS18B20_DQ, PIN_LOW); //拉低DQ rt_hw_us_delay(360); //拉低750us(480~960us) rt_pin_write(DS18B20_DQ, PIN_HIGH); //拉高DQ } //等待DS18B20应答,有应答返回0,无应答返回1 uint8_t DS18B20_Check(void) { uint8_t retry=0; //进入接收模式,等待应答信号 //等待时间 rt_pin_mode(DS18B20_DQ, PIN_MODE_INPUT); //输入模式 rt_hw_us_delay(15); //等待15~60us while(rt_pin_read(DS18B20_DQ)&&retry<30) //最多再等待120us { retry++; rt_hw_us_delay(1); }; if(retry>=30) return 1; //120us未响应，则判断未检测到 else retry=0; //DS18B20开始拉低DQ while(!rt_pin_read(DS18B20_DQ)&&retry<38) //最长拉低240us { retry++; rt_hw_us_delay(1); }; if(retry>=38) return 1; return 0; } //写字节到DS18B20 void DS18B20_Write_Byte(uint8_t dat) { uint8_t j; uint8_t temp; rt_pin_mode(DS18B20_DQ, PIN_MODE_OUTPUT); //输出模式 for(j=1;j<=8;j++) { temp=dat&0x01; dat=dat>>1; if (temp) //输出高 { rt_pin_write(DS18B20_DQ, PIN_LOW); //拉低DQ rt_hw_us_delay(1); //延时2us rt_pin_write(DS18B20_DQ, PIN_HIGH); //拉高DQ rt_hw_us_delay(29); //延时60us } else //输出低 { rt_pin_write(DS18B20_DQ, PIN_LOW); //拉低DQ rt_hw_us_delay(29); //延时60us rt_pin_write(DS18B20_DQ, PIN_HIGH); //拉高DQ rt_hw_us_delay(1); //延时2us } } rt_pin_mode(DS18B20_DQ, PIN_MODE_INPUT); //输入模式 } //从DS18B20读位 uint8_t DS18B20_Read_Bit(void) { uint8_t data; rt_pin_mode(DS18B20_DQ, PIN_MODE_OUTPUT); //输出模式 rt_pin_write(DS18B20_DQ, PIN_LOW); //拉低DQ rt_hw_us_delay(1); //延时2us rt_pin_write(DS18B20_DQ, PIN_HIGH); //拉高DQ rt_pin_mode(DS18B20_DQ, PIN_MODE_INPUT); //输入模式 rt_hw_us_delay(2); //延时12us if(rt_pin_read(DS18B20_DQ)) //读DQ数据 data=1; else data=0; rt_hw_us_delay(25); //延时50us return data; } //从DS18B20读字节 uint8_t DS18B20_Read_Byte(void) { uint8_t i, j, dat=0; for(i=1;i<=8;i++) { j=DS18B20_Read_Bit(); dat=(j<<7)|(dat>>1); } return dat; } //开始温度转换 void DS18B20_Start(void) { DS18B20_Rst(); DS18B20_Check(); DS18B20_Write_Byte(0xcc); DS18B20_Write_Byte(0x44); } //读取温度值 float DS18B20_Get_Temp(void) { uint8_t sign; //温度符号,0为-,1为+ uint8_t TL,TH; uint16_t temp; float temp1; DS18B20_Start (); rt_thread_mdelay(800); //等待转换完成 DS18B20_Rst(); DS18B20_Check(); DS18B20_Write_Byte(0xcc); DS18B20_Write_Byte(0xbe); TL=DS18B20_Read_Byte(); TH=DS18B20_Read_Byte(); if(TH>7) { TH=~TH; TL=~TL; sign=0; //温度为负 } else sign=1; //温度为正 temp=TH; //高八位 temp<<=8; temp+=TL; //低八位 temp1=(float)temp * 0.0625; //转换实际温度 if(sign) return temp1; //返回温度值 else return -temp1; } uint8_t DS18B20_Init(void) { DS18B20_Rst(); return DS18B20_Check(); } int main(void) { float Temperature = 0.0; uint8_t pin = rt_pin_get("PA.1"); rt_pin_mode(pin, PIN_MODE_OUTPUT); rt_pin_mode(DS18B20_DQ, PIN_MODE_OUTPUT); if(DS18B20_Init()) { rt_kprintf(" Not detected DS18B20\n "); } else { rt_kprintf(" Detected DS18B20\n "); } while (1) { rt_pin_write(pin, PIN_LOW); rt_thread_mdelay(1000); rt_pin_write(pin, PIN_HIGH); rt_thread_mdelay(1000); Temperature = DS18B20_Get_Temp(); rt_kprintf("\nTemperature:%.1f", Temperature); } }
复制代码
同时添加头文件#include <stdio.h>
编译下载程序，效果如下：
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