• 树莓派进阶之路 (015)


    参考:http://shumeipai.nxez.com/2013/10/03/raspberry-pi-temperature-sensor-monitors.html

    第一步,允许单总线接口

    sudo raspi-config进入interfacingoptions

    enable 1-wire interface

    第二步,接线 

    接BCM编码为4即图上物理引脚7

    第三步,升级内核

    sudo apt-get update
    sudo apt-get upgrade
    pi@raspberrypi:~$ cd /sys/bus/w1/devices/
    pi@raspberrypi:/sys/bus/w1/devices$ ls
    28-00000xxxxxx w1_bus_master1

    第四步,查看当前温度

    cd 28-00000xxxxxx cat w1_slave
    显示:
    46 01 4b 46 7f ff 0c 10 2f : crc=2f YES
    46 01 4b 46 7f ff 0c 10 2f t=20375
    第二行的t=20375就是当前的温度值,要换算成摄氏度,除以1000,即当前温度为20

    python

     1 #!/usr/bin/python3
     2 import os,time
     3 
     4 device_file ='/sys/bus/w1/devices/28-031681e171ff/w1_slave'
     5 
     6 def read_temp_raw():
     7     f = open(device_file,'r')
     8     lines = f.readlines()
     9     f.close()
    10     return lines
    11 
    12 def read_temp():
    13     lines = read_temp_raw()
    14     while lines[0].strip()[-3:] != 'YES':
    15         time.sleep(0.2)
    16         lines = read_temp_raw()
    17     equals_pos = lines[1].find('t=')
    18     if equals_pos != -1:
    19         temp_string = lines[1][equals_pos+2:]
    20         temp_c = float(temp_string)/1000.0
    21     return temp_c
    22 
    23 while True:
    24     print('temp C = %f'%read_temp())
    25     time.sleep(1)

    打印结果:

    1 pi@raspberrypi:~/myPython $ ./temp_ds18b20.py 
    2 temp C = 20.687000
    3 temp C = 20.687000
    4 temp C = 20.687000
    5 temp C = 20.750000
    6 temp C = 20.750000
    7 temp C = 20.750000

    C语言代码:

     1 #include <stdio.h>
     2 #include <stdlib.h>
     3 #include <string.h>
     4 #include <dirent.h>
     5 #include <unistd.h>
     6 #include <sys/types.h>
     7 #include <sys/stat.h>
     8 #include <fcntl.h>
     9 #include <hiredis/hiredis.h>
    10 
    11 
    12 int Open_send(char *base){                      //打开发送数据
    13     int fd, size;
    14     char buffer[1024];
    15         fd = open(base,O_RDONLY);
    16         lseek(fd,69,SEEK_SET);
    17         size = read(fd,buffer,sizeof(buffer));
    18         close(fd);
    19         printf("temp C = %f
    ",(float)atoi(buffer)/1000.0);
    20     return 0;
    21 }
    22 
    23 int readFileList(char *basePath)                //文件查找
    24 {
    25     DIR *dir;
    26     struct dirent *ptr;
    27     char base[1024];
    28 
    29     if ((dir=opendir(basePath)) == NULL){
    30         perror("Open dir error...");
    31         exit(1);
    32     }
    33     while ((ptr=readdir(dir)) != NULL)
    34     {
    35         if(strcmp(ptr->d_name,".")==0 || strcmp(ptr->d_name,"..")==0)    ///current dir OR parrent dir
    36             continue;
    37         else if(ptr->d_type == 10){
    38             memset(base,'',sizeof(base));
    39             sprintf(base,"%s",ptr->d_name);
    40             if((strcmp("27",base)<0)&&(strcmp("29",base)>0)){
    41                 sprintf(base,"%s/%s/w1_slave",basePath,ptr->d_name);
    42                 //printf("%s
    ",base);
    43                 while(1)
    44                 Open_send(base);
    45             }
    46         }
    47     }
    48     closedir(dir);
    49     return 1;
    50 }
    51 
    52 int main(void)
    53 {
    54     DIR *dir;
    55     char basePath[1024];
    56     memset(basePath,'',sizeof(basePath));
    57     strcpy(basePath,"/sys/bus/w1/devices");
    58     readFileList(basePath);
    59     return 0;
    60 }

    =======================================华丽的分割线=======================================

    由于根据官方的说法,在2015-02-16之后的Raspbain版本,为了防止GPIO的冲突,使用了新的dt策略,更改了原来单总线gpio的配置方法,需要在配置文件中添加gpiopin=8,配置单总线的gpio引脚。

    修改配置:

    sudo vim /boot/config.txt

    在最后一行手动添加这个,保存并重启树莓派。

    dtoverlay=w1-gpio-pullup,gpiopin=8

    在通过配置sudo raspi-config进入interfacingoptions配置单总线时,系统会在/boot/config.txt文件添加dtoverlay=w1-gpio-pullupz,只需要在后面通过gpiopin指定引脚。

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  • 原文地址:https://www.cnblogs.com/jikexianfeng/p/7086799.html
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