diff -r 9c7119ac0455 -r 89dd2b691701 lib/dht11.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/dht11.c	Thu May 08 22:36:51 2014 +0200
@@ -0,0 +1,167 @@
+/*****************************************************************************
+ * Copyright (C) 2008-2014
+ *   
+ * Michiel Broek <mbroek at mbse dot eu>
+ *
+ * This file is part of the mbsePi-apps
+ *
+ * Parts original by CurlyMo from the pilight project.
+ *
+ * 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 "../config.h"
+#include "mbselib.h"
+
+#ifdef HAVE_WIRINGPI_H
+
+#define MAXTIMINGS 100
+
+int		dht11_pin = -1;
+int		dht11_temperature = -1;
+int		dht11_humidity = -1;
+int		dht11_valid = false;
+int		dht11_t_offset = 0;
+int		dht11_h_offset = 0;
+
+
+
+static uint8_t sizecvt(const int read_value) {
+    /* 
+     * digitalRead() and friends from wiringpi are defined as returning a value
+     *            < 256. However, they are returned as int() types. This is a safety function 
+     */
+    if (read_value > 255 || read_value < 0) {
+	syslog(LOG_NOTICE, "invalid data from wiringPi library");
+    }
+		  
+    return (uint8_t)read_value;
+}
+
+
+
+/*
+ * DHT11 sensor read. This should be used in a thread loop.
+ */
+void dht11Read(void) {
+    int         	tries = 5;
+    unsigned short	got_correct_data = 0;
+
+    if (dht11_pin == -1)
+	return;
+
+    while (tries && !got_correct_data) {
+	uint8_t	laststate = HIGH;
+	uint8_t	counter = 0;
+	uint8_t	j = 0, i = 0;
+	int	dht11_dat[5] = {0,0,0,0,0};
+
+	/*
+	 * Select output mode to send the start signal.
+	 */
+	pinMode(dht11_pin, OUTPUT);                 
+	digitalWrite(dht11_pin, HIGH);
+	usleep(1000);
+
+	/*
+	 * Low for at least 18 milliseconds
+	 */
+	digitalWrite(dht11_pin, LOW);
+	usleep(20000);
+	digitalWrite(dht11_pin, HIGH);
+	pinMode(dht11_pin, INPUT);
+
+	/*
+	 * Detect change and read data
+	 */
+	for (i=0; i<MAXTIMINGS; i++) {
+	    counter = 0;
+	    delayMicroseconds(10);
+	    while (sizecvt(digitalRead(dht11_pin)) == laststate) {
+		counter++;
+		delayMicroseconds(1);
+		if (counter == 255) {
+		    break;
+		}
+	    }
+	    laststate = sizecvt(digitalRead(dht11_pin));
+
+	    if (counter == 255) 
+		break;
+
+	    /*
+	     * ignore first 3 transitions
+	     */
+	    if ((i >= 4) && (i%2 == 0)) {
+
+		// shove each bit into the storage bytes
+		dht11_dat[(int)((double)j/8)] <<= 1;
+		if (counter > 16)
+		    dht11_dat[(int)((double)j/8)] |= 1;
+		j++;
+	    }
+	}
+
+	/*
+	 * If there is no sensor, j = 0
+	 */
+	if ((counter == 255) && (j == 0)) {
+	    if (dht11_temperature != -1) {
+		syslog(LOG_NOTICE, "dht11 sensor disappeared");
+	    }
+	    dht11_temperature = -1;
+	    dht11_humidity = -1;
+	    dht11_valid = false;
+	} else {
+
+	    /*
+	     * check we read 40 bits (8bit x 5 ) + verify checksum in the last byte
+	     * print it out if data is good
+	     */
+	    if ((j >= 40) && (dht11_dat[4] == ((dht11_dat[0] + dht11_dat[1] + dht11_dat[2] + dht11_dat[3]) & 0xFF))) {
+		got_correct_data = 1;
+
+		int h = dht11_dat[0] + dht11_dat[1];
+		int t = (dht11_dat[2] & 0x7F) + dht11_dat[3];
+		t += dht11_t_offset;
+		h += dht11_h_offset;
+
+		if ((dht11_dat[2] & 0x80) != 0) 
+		    t *= -1;
+
+		dht11_temperature = t;
+		dht11_humidity = h;
+		dht11_valid = true;
+	    } else {
+		tries--;
+		if (tries == 0)
+		    syslog(LOG_INFO, "dht11 data checksum was wrong 5 times");
+		usleep(100000);
+	    }
+	}
+    }
+}
+
+
+
+void dht11Init(int pin, int t_offset, int h_offset) {
+    dht11_pin = pin;
+    dht11_t_offset = t_offset;
+    dht11_h_offset = h_offset;
+}
+
+
+#endif
+