| | |
| | | /********************************************************************************* |
| | | * Copyright: (C) 2018 LingYun IoT System Studio |
| | | * Copyright: (C) 2023 LingYun IoT System Studio |
| | | * All rights reserved. |
| | | * |
| | | * Filename: ds18b20.c |
| | | * Description: This file is temperature sensor DS18B20 code |
| | | * |
| | | * Version: 1.0.0(2018/10/14) |
| | | * Version: 1.0.0(2023/8/10) |
| | | * Author: Guo Wenxue <guowenxue@gmail.com> |
| | | * ChangeLog: 1, Release initial version on "2018/10/14 12:13:26" |
| | | * ChangeLog: 1, Release initial version on "2023/8/10 12:13:26" |
| | | * |
| | | * Pin connection: |
| | | * |
| | | * DS18B20 Module Raspberry Pi Board |
| | | * VCC <-----> #Pin1(3.3V) |
| | | * DQ <-----> #Pin7(BCM GPIO4) |
| | | * GND <-----> GND |
| | | * |
| | | * /boot/config.txt: |
| | | * |
| | | * dtoverlay=w1-gpio-pullup,gpiopin=4 |
| | | * |
| | | ********************************************************************************/ |
| | | |
| | | |
| | | #include <stdio.h> |
| | | #include <stdlib.h> |
| | |
| | | pi@raspberrypi:~/guowenxue $ cat /sys/bus/w1/devices/28-041731f7c0ff/w1_slave |
| | | 3a 01 4b 46 7f ff 0c 10 a5 : crc=a5 YES |
| | | 3a 01 4b 46 7f ff 0c 10 a5 t=19625 |
| | | */ |
| | | */ |
| | | |
| | | int ds18b20_get_temperature(float *temp) |
| | | { |
| | |
| | | |
| | | if( !temp ) |
| | | { |
| | | return -1; |
| | | return -1; |
| | | } |
| | | |
| | | /*+-------------------------------------------------------------------+ |
| | |
| | | *+-------------------------------------------------------------------+*/ |
| | | if((dirp = opendir(w1_path)) == NULL) |
| | | { |
| | | log_error("opendir '%s' error: %s\n", w1_path, strerror(errno)); |
| | | log_error("opendir error: %s\n", strerror(errno)); |
| | | return -2; |
| | | } |
| | | |
| | |
| | | /* find and get the chipset SN filename */ |
| | | strcpy(chip,direntp->d_name); |
| | | found = 1; |
| | | break; |
| | | break; |
| | | } |
| | | } |
| | | closedir(dirp); |
| | | |
| | | if( !found ) |
| | | { |
| | | log_error("Can not find ds18b20 in %s\n", w1_path); |
| | | return -3; |
| | | log_error("Can not find ds18b20 in %s\n", w1_path); |
| | | return -3; |
| | | } |
| | | |
| | | /* get DS18B20 sample file full path: /sys/bus/w1/devices/28-xxxx/w1_slave */ |
| | |
| | | /* open file /sys/bus/w1/devices/28-xxxx/w1_slave to get temperature */ |
| | | if( (fd=open(w1_path, O_RDONLY)) < 0 ) |
| | | { |
| | | log_error("open %s error: %s\n", w1_path, strerror(errno)); |
| | | return -4; |
| | | log_error("open %s error: %s\n", w1_path, strerror(errno)); |
| | | return -4; |
| | | } |
| | | |
| | | if(read(fd, buf, sizeof(buf)) < 0) |
| | | { |
| | | log_error("read %s error: %s\n", w1_path, strerror(errno)); |
| | | return -5; |
| | | log_error("read %s error: %s\n", w1_path, strerror(errno)); |
| | | return -5; |
| | | } |
| | | |
| | | ptr = strstr(buf, "t="); |
| | | if( !ptr ) |
| | | { |
| | | log_error("ERROR: Can not get temperature\n"); |
| | | return -6; |
| | | log_error("ERROR: Can not get temperature\n"); |
| | | return -6; |
| | | } |
| | | |
| | | ptr+=2; |