thermferm/sensors.c

/*****************************************************************************
 * Copyright (C) 2014
 *   
 * Michiel Broek <mbroek at mbse dot eu>
 *
 * This file is part of the mbsePi-apps
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * mbsePi-apps is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with EC-65K; see the file COPYING.  If not, write to the Free
 * Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *****************************************************************************/

#include "thermferm.h"


extern int		debug;
extern sys_config	Config;
extern int		my_shutdown;


#ifdef HAVE_WIRINGPI_H
PI_THREAD (my_sensors_loop)
#else
void *my_sensors_loop(void *threadid)
#endif
{
    w1_therm		*tmp1, *old1;
    char		*device, line[60], *p = NULL;
    FILE		*fp;
    int			temp, rc, deviation;

    syslog(LOG_NOTICE, "Thread my_sensors_loop started");
    if (debug)
	fprintf(stdout, "Thread my_sensors_loop started\n");

    /*
     * Loop forever until the external shutdown variable is set.
     */
    for (;;) {

    	/*
    	 * Here send our 1-wire sensors values
    	 */
    	for (tmp1 = Config.w1therms; tmp1; tmp1 = old1) {
	    old1 = tmp1->next;

	    if (my_shutdown) {
		syslog(LOG_NOTICE, "Thread my_sensors_loop stopped");
		if (debug)
		    fprintf(stdout, "Thread my_sensors_loop stopped\n");
	    	return 0;
	    }

	    /*
	     * Build path to the on-wire sensor
	     */
	    device = xstrcpy((char *)"/sys/bus/w1/devices/");
	    device = xstrcat(device, tmp1->master);
	    device = xstrcat(device, (char *)"/");
	    device = xstrcat(device, tmp1->name);
	    device = xstrcat(device, (char *)"/w1_slave");

	    /*
	     * Read sensor data
	     */
	    if ((fp = fopen(device, "r"))) {
		/*
		 * The output looks like:
		 * 72 01 4b 46 7f ff 0e 10 57 : crc=57 YES
		 * 72 01 4b 46 7f ff 0e 10 57 t=23125
		 */
		fgets(line, 50, fp);
		line[strlen(line)-1] = '\0';
		if ((line[36] == 'Y') && (line[37] == 'E')) {
		    /*
		     * CRC is Ok, continue
		     */
		    fgets(line, 50, fp);
		    line[strlen(line)-1] = '\0';
		    strtok(line, (char *)"=");
		    p = strtok(NULL, (char *)"=");
		    rc = sscanf(p, "%d", &temp);
		    if ((rc == 1) && (tmp1->lastval != temp)) {
			/*
			 * It is possible to have read errors or extreme values.
			 * This can happen with bad connections so we compare the
			 * value with the previous one. If the difference is too
			 * much, we don't send that value. That also means that if
			 * the next value is ok again, it will be marked invalid too.
			 * Maximum error is 20 degrees for now.
			 */
			deviation = 20000;
			if ( (tmp1->lastval == 0) ||
			     (tmp1->lastval && (temp > (tmp1->lastval - deviation)) && (temp < (tmp1->lastval + deviation))) ) {
			    /*
			     * Temperature is changed and valid, set flag.
			     */
			    tmp1->update = TRUE;
			} else {
			    syslog(LOG_NOTICE, "deviation error deviation=%d, old=%d new=%d", deviation, tmp1->lastval, temp);
			    if (debug) {
				fprintf(stdout, "deviation error deviation=%d, old=%d new=%d\n", deviation, tmp1->lastval, temp);
			    }
			}
			tmp1->lastval = temp;
		    }
		} else {
		    syslog(LOG_NOTICE, "sensor %s/%s CRC error", tmp1->master, tmp1->name);
		}
		fclose(fp);
		tmp1->present = 1;
	    } else {
		tmp1->present = 0;
		if (debug)
		    printf("sensor %s is missing\n", tmp1->name);
	    }

	    free(device);
	    device = NULL;
    	}
    }
}