linux onewire(一线通讯的应用程序)

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include
#include
#include

#define DS18B20_DEV            "/sys/devices/w1_bus_master1/28-0004432e03ff/w1_slave"

int get_temp(float *value, const char *dev)
{
    int ret;
    FILE *fp;
    char buf1[100], buf2[100];
    
    fp = fopen(dev, "r");
    if (fp == NULL) {
        perror("fopen err\n");
        return -1;
    }
    
    fgets(buf1, 100, fp);
    sscanf(buf1, "%*[^:]: crc=%*[^ ]%s\n", buf2); //过滤：号前的，跳过：CRC=，过滤空格前的，最后取
    if (strcmp(buf2, "YES") == 0) {
        fgets(buf1, 100, fp);
        sscanf(buf1, "%*[^t]t=%s\n", buf2);
        *value = atoi(buf2) * 1.0 / 1000;
        ret = 0;
    } else {
        fprintf(stderr, "CRC error\n");
        ret = -1;
    }
    
    fclose(fp);
    return ret;
}

int main(void)
{
    float value;
    if (get_temp(&value, DS18B20_DEV) == 0)
        printf("%0.3f ℃\n", value);
    return 0;
}