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Comments removed, DHT11 library and Fritzing file added.
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| // | ||
| // FILE: dht11.cpp | ||
| // VERSION: 0.3.2 | ||
| // PURPOSE: DHT11 Temperature & Humidity Sensor library for Arduino | ||
| // LICENSE: GPL v3 (http://www.gnu.org/licenses/gpl.html) | ||
| // | ||
| // DATASHEET: http://www.micro4you.com/files/sensor/DHT11.pdf | ||
| // | ||
| // HISTORY: | ||
| // George Hadjikyriacou - Original version (??) | ||
| // Mod by SimKard - Version 0.2 (24/11/2010) | ||
| // Mod by Rob Tillaart - Version 0.3 (28/03/2011) | ||
| // + added comments | ||
| // + removed all non DHT11 specific code | ||
| // + added references | ||
| // | ||
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| #include "dht11.h" | ||
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| // returnvalues: | ||
| // 0 : OK | ||
| // -1 : checksum error | ||
| // -2 : timeout | ||
| int dht11::read(int pin) | ||
| { | ||
| // BUFFER TO RECEIVE | ||
| uint8_t bits[5]; | ||
| uint8_t cnt = 7; | ||
| uint8_t idx = 0; | ||
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| // EMPTY BUFFER | ||
| for (int i=0; i< 5; i++) bits[i] = 0; | ||
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| // REQUEST SAMPLE | ||
| pinMode(pin, OUTPUT); | ||
| digitalWrite(pin, LOW); | ||
| delay(18); | ||
| digitalWrite(pin, HIGH); | ||
| delayMicroseconds(40); | ||
| pinMode(pin, INPUT); | ||
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| // ACKNOWLEDGE or TIMEOUT | ||
| unsigned int loopCnt = 10000; | ||
| while(digitalRead(pin) == LOW) | ||
| if (loopCnt-- == 0) return -2; | ||
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| loopCnt = 10000; | ||
| while(digitalRead(pin) == HIGH) | ||
| if (loopCnt-- == 0) return -2; | ||
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| // READ OUTPUT - 40 BITS => 5 BYTES or TIMEOUT | ||
| for (int i=0; i<40; i++) | ||
| { | ||
| loopCnt = 10000; | ||
| while(digitalRead(pin) == LOW) | ||
| if (loopCnt-- == 0) return -2; | ||
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| unsigned long t = micros(); | ||
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| loopCnt = 10000; | ||
| while(digitalRead(pin) == HIGH) | ||
| if (loopCnt-- == 0) return -2; | ||
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| if ((micros() - t) > 40) bits[idx] |= (1 << cnt); | ||
| if (cnt == 0) // next byte? | ||
| { | ||
| cnt = 7; // restart at MSB | ||
| idx++; // next byte! | ||
| } | ||
| else cnt--; | ||
| } | ||
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| // WRITE TO RIGHT VARS | ||
| // as bits[1] and bits[3] are allways zero they are omitted in formulas. | ||
| humidity = bits[0]; | ||
| temperature = bits[2]; | ||
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| uint8_t sum = bits[0] + bits[2]; | ||
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| if (bits[4] != sum) return -1; | ||
| return 0; | ||
| } | ||
| // | ||
| // END OF FILE | ||
| // |
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| // | ||
| // FILE: dht11.h | ||
| // VERSION: 0.3.2 | ||
| // PURPOSE: DHT11 Temperature & Humidity Sensor library for Arduino | ||
| // LICENSE: GPL v3 (http://www.gnu.org/licenses/gpl.html) | ||
| // | ||
| // DATASHEET: http://www.micro4you.com/files/sensor/DHT11.pdf | ||
| // | ||
| // URL: http://arduino.cc/playground/Main/DHT11Lib | ||
| // | ||
| // HISTORY: | ||
| // George Hadjikyriacou - Original version | ||
| // see dht.cpp file | ||
| // *** Terry King: Changed include Arduino.h for 1.0x | ||
| // include core Wiring API and now Arduino | ||
| #if defined(ARDUINO) && ARDUINO >= 100 | ||
| #include "Arduino.h" | ||
| #else | ||
| #include "WProgram.h" | ||
| #endif | ||
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| #ifndef dht11_h | ||
| #define dht11_h | ||
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| #define DHT11LIB_VERSION "0.3.2" | ||
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| class dht11 | ||
| { | ||
| public: | ||
| int read(int pin); | ||
| int humidity; | ||
| int temperature; | ||
| }; | ||
| #endif | ||
| // | ||
| // END OF FILE | ||
| // |
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| /* YourDuino.com Example Software Sketch | ||
| DHT11 Humidity and Temperature Sensor test | ||
| Credits: Rob Tillaart | ||
| http://arduino-direct.com/sunshop/index.php?l=product_detail&p=162 | ||
| [email protected] */ | ||
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| /*-----( Import needed libraries )-----*/ | ||
| #include <dht11.h> | ||
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| /*-----( Declare objects )-----*/ | ||
| dht11 DHT11; | ||
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| /*-----( Declare Constants, Pin Numbers )-----*/ | ||
| #define DHT11PIN 2 | ||
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| void setup() /*----( SETUP: RUNS ONCE )----*/ | ||
| { | ||
| Serial.begin(9600); | ||
| Serial.println("DHT11 TEST PROGRAM "); | ||
| Serial.print("LIBRARY VERSION: "); | ||
| Serial.println(DHT11LIB_VERSION); | ||
| Serial.println(); | ||
| }/*--(end setup )---*/ | ||
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| void loop() /*----( LOOP: RUNS CONSTANTLY )----*/ | ||
| { | ||
| Serial.println("\n"); | ||
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| int chk = DHT11.read(DHT11PIN); | ||
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| Serial.print("Read sensor: "); | ||
| switch (chk) | ||
| { | ||
| case 0: Serial.println("OK"); break; | ||
| case -1: Serial.println("Checksum error"); break; | ||
| case -2: Serial.println("Time out error"); break; | ||
| default: Serial.println("Unknown error"); break; | ||
| } | ||
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| Serial.print("Humidity (%): "); | ||
| Serial.println((float)DHT11.humidity, 2); | ||
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| Serial.print("Temperature (oC): "); | ||
| Serial.println((float)DHT11.temperature, 2); | ||
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| Serial.print("Temperature (oF): "); | ||
| Serial.println(Fahrenheit(DHT11.temperature), 2); | ||
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| Serial.print("Temperature (K): "); | ||
| Serial.println(Kelvin(DHT11.temperature), 2); | ||
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| Serial.print("Dew Point (oC): "); | ||
| Serial.println(dewPoint(DHT11.temperature, DHT11.humidity)); | ||
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| Serial.print("Dew PointFast (oC): "); | ||
| Serial.println(dewPointFast(DHT11.temperature, DHT11.humidity)); | ||
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| delay(2000); | ||
| }/* --(end main loop )-- */ | ||
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| /*-----( Declare User-written Functions )-----*/ | ||
| // | ||
| //Celsius to Fahrenheit conversion | ||
| double Fahrenheit(double celsius) | ||
| { | ||
| return 1.8 * celsius + 32; | ||
| } | ||
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| //Celsius to Kelvin conversion | ||
| double Kelvin(double celsius) | ||
| { | ||
| return celsius + 273.15; | ||
| } | ||
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| // dewPoint function NOAA | ||
| // reference: http://wahiduddin.net/calc/density_algorithms.htm | ||
| double dewPoint(double celsius, double humidity) | ||
| { | ||
| double A0= 373.15/(273.15 + celsius); | ||
| double SUM = -7.90298 * (A0-1); | ||
| SUM += 5.02808 * log10(A0); | ||
| SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ; | ||
| SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ; | ||
| SUM += log10(1013.246); | ||
| double VP = pow(10, SUM-3) * humidity; | ||
| double T = log(VP/0.61078); // temp var | ||
| return (241.88 * T) / (17.558-T); | ||
| } | ||
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| // delta max = 0.6544 wrt dewPoint() | ||
| // 5x faster than dewPoint() | ||
| // reference: http://en.wikipedia.org/wiki/Dew_point | ||
| double dewPointFast(double celsius, double humidity) | ||
| { | ||
| double a = 17.271; | ||
| double b = 237.7; | ||
| double temp = (a * celsius) / (b + celsius) + log(humidity/100); | ||
| double Td = (b * temp) / (a - temp); | ||
| return Td; | ||
| } | ||
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| /* ( THE END ) */ | ||
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