restructured

FlippR-Driver/lib/wiringPi/ds18b20.c

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+/*
+ * ds18b20.c:
+ *	Extend wiringPi with the DS18B20 1-Wire temperature sensor.
+ *	This is used in the Pi Weather Station and many other places.
+ *	Copyright (c) 2016 Gordon Henderson
+ ***********************************************************************
+ * This file is part of wiringPi:
+ *	https://projects.drogon.net/raspberry-pi/wiringpi/
+ *
+ *    wiringPi is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU Lesser General Public License as
+ *    published by the Free Software Foundation, either version 3 of the
+ *    License, or (at your option) any later version.
+ *
+ *    wiringPi 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 Lesser General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Lesser General Public
+ *    License along with wiringPi.
+ *    If not, see <http://www.gnu.org/licenses/>.
+ ***********************************************************************
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include <unistd.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <malloc.h>
+#include <ctype.h>
+
+#include "wiringPi.h"
+
+#include "ds18b20.h"
+
+#define	W1_PREFIX	"/sys/bus/w1/devices/28-"
+#define	W1_POSTFIX	"/w1_slave"
+
+
+/*
+ * myAnalogRead:
+ *********************************************************************************
+ */
+
+static int myAnalogRead (struct wiringPiNodeStruct *node, int pin)
+{
+  int  chan = pin - node->pinBase ;
+  int  fd = node->fd ;
+  char buffer [4096] ;
+  char *p ;
+  int  temp, sign ;
+
+  if (chan != 0)
+    return -9999 ;
+
+// Rewind the file - we're keeping it open to keep things going
+//	smoothly
+
+  lseek (fd, 0, SEEK_SET) ;
+
+// Read the file - we know it's only a couple of lines, so this ought to be
+//	more than enough
+
+  if (read (fd, buffer, 4096) <= 0)	// Read nothing, or it failed in some odd way
+    return -9998 ;
+
+// Look for YES, then t=
+
+  if (strstr (buffer, "YES") == NULL)
+    return -9997 ;
+
+  if ((p = strstr (buffer, "t=")) == NULL)
+    return -9996 ;
+
+// p points to the 't', so we skip over it...
+
+  p += 2 ;
+
+// and extract the number
+//	(without caring about overflow)
+
+
+  if (*p == '-')	// Negative number?
+  {
+    sign = -1 ;
+    ++p ;
+  }
+  else
+    sign = 1 ;
+
+  temp = 0 ;
+  while (isdigit (*p))
+  {
+    temp = temp * 10 + (*p - '0') ;
+    ++p ;
+  }
+
+// We know it returns temp * 1000, but we only really want temp * 10, so
+//	do a bit of rounding...
+
+  temp = (temp + 50) / 100 ;
+  return temp * sign ;
+}
+
+
+/*
+ * ds18b20Setup:
+ *	Create a new instance of a DS18B20 temperature sensor.
+ *********************************************************************************
+ */
+
+int ds18b20Setup (const int pinBase, const char *deviceId)
+{
+  int fd ;
+  struct wiringPiNodeStruct *node ;
+  char *fileName ;
+
+// Allocate space for the filename
+
+  if ((fileName = malloc (strlen (W1_PREFIX) + strlen (W1_POSTFIX) + strlen (deviceId) + 1)) == NULL)
+    return FALSE ;
+
+  sprintf (fileName, "%s%s%s", W1_PREFIX, deviceId, W1_POSTFIX) ;
+
+  fd = open (fileName, O_RDONLY) ;
+
+  free (fileName) ;
+
+  if (fd < 0)
+    return FALSE ;
+
+// We'll keep the file open, to make access a little faster
+//	although it's very slow reading these things anyway )-:
+
+  node = wiringPiNewNode (pinBase, 1) ;
+
+  node->fd         = fd ;
+  node->analogRead = myAnalogRead ;
+
+  return TRUE ;
+}