Wed, 04 Jun 2014 16:00:35 +0200
Simple detection for the same log lines
/***************************************************************************** * 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 "dht11.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"); } else { syslog(LOG_NOTICE, "dht11 sensor not present"); } dht11_temperature = -1; dht11_humidity = -1; dht11_valid = false; return; } /* * 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; } int main(int argc, char *argv[]) { int PIN = 3; if (wiringPiSetup() == -1) return 0; dht11Init(PIN, 1, 6); dht11Read(); if (dht11_valid) { fprintf(stdout, "DHT11: temperature %d degrees, humidity %d%%\n", dht11_temperature, dht11_humidity); } else { fprintf(stdout, "DHT11: no valid data or sensor not connected\n"); } exit(0); } #else int main(int argc, char *argv[]) { fprintf(stderr, "This program does nothing without the wiringPi library\n"); return 0; } #endif