--- /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
+