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documented DHT

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Jan Hoffmann 2019-07-04 17:06:42 +02:00
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commit dd455428a0
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164
DHT.cpp
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@ -1,14 +1,42 @@
/* DHT library /*!
* @file DHT.cpp
MIT license *
written by Adafruit Industries * @mainpage DHT series of low cost temperature/humidity sensors.
*
* @section intro_sec Introduction
*
* This is a library for DHT series of low cost temperature/humidity sensors.
*
* You must have Adafruit Unified Sensor Library library installed to use this
* class.
*
* Adafruit invests time and resources providing this open source code,
* please support Adafruit andopen-source hardware by purchasing products
* from Adafruit!
*
* @section author Author
*
* Written by Adafruit Industries.
*
* @section license License
*
* MIT license, all text above must be included in any redistribution
*/ */
#include "DHT.h" #include "DHT.h"
#define MIN_INTERVAL 2000 #define MIN_INTERVAL 2000 /**< min interval value */
#define TIMEOUT -1 #define TIMEOUT -1 /**< timeout on */
/*!
* @brief Instantiates a new DHT class
* @param pin
* pin number that sensor is connected
* @param type
* type of sensor
* @param count
* number of sensors
*/
DHT::DHT(uint8_t pin, uint8_t type, uint8_t count) { DHT::DHT(uint8_t pin, uint8_t type, uint8_t count) {
_pin = pin; _pin = pin;
_type = type; _type = type;
@ -16,14 +44,19 @@ DHT::DHT(uint8_t pin, uint8_t type, uint8_t count) {
_bit = digitalPinToBitMask(pin); _bit = digitalPinToBitMask(pin);
_port = digitalPinToPort(pin); _port = digitalPinToPort(pin);
#endif #endif
_maxcycles = microsecondsToClockCycles(1000); // 1 millisecond timeout for _maxcycles =
microsecondsToClockCycles(1000); // 1 millisecond timeout for
// reading pulses from DHT sensor. // reading pulses from DHT sensor.
// Note that count is now ignored as the DHT reading algorithm adjusts itself // Note that count is now ignored as the DHT reading algorithm adjusts itself
// based on the speed of the processor. // based on the speed of the processor.
} }
// Optionally pass pull-up time (in microseconds) before DHT reading starts. /*!
// Default is 55 (see function declaration in DHT.h). * @brief Setup sensor pins and set pull timings
* @param usec
* Optionally pass pull-up time (in microseconds) before DHT reading
*starts. Default is 55 (see function declaration in DHT.h).
*/
void DHT::begin(uint8_t usec) { void DHT::begin(uint8_t usec) {
// set up the pins! // set up the pins!
pinMode(_pin, INPUT_PULLUP); pinMode(_pin, INPUT_PULLUP);
@ -31,11 +64,21 @@ void DHT::begin(uint8_t usec) {
// >= MIN_INTERVAL right away. Note that this assignment wraps around, // >= MIN_INTERVAL right away. Note that this assignment wraps around,
// but so will the subtraction. // but so will the subtraction.
_lastreadtime = millis() - MIN_INTERVAL; _lastreadtime = millis() - MIN_INTERVAL;
DEBUG_PRINT("DHT max clock cycles: "); DEBUG_PRINTLN(_maxcycles, DEC); DEBUG_PRINT("DHT max clock cycles: ");
DEBUG_PRINTLN(_maxcycles, DEC);
pullTime = usec; pullTime = usec;
} }
//boolean S == Scale. True == Fahrenheit; False == Celcius /*!
* @brief Read temperature
* @param S
* Scale. Boolean value:
* - true = Fahrenheit
* - false = Celcius
* @param force
* true if in force mode
* @return Temperature value in selected scale
*/
float DHT::readTemperature(bool S, bool force) { float DHT::readTemperature(bool S, bool force) {
float f = NAN; float f = NAN;
@ -77,14 +120,28 @@ float DHT::readTemperature(bool S, bool force) {
return f; return f;
} }
float DHT::convertCtoF(float c) { /*!
return c * 1.8 + 32; * @brief Converts Celcius to Fahrenheit
} * @param c
* value in Celcius
* @return float value in Fahrenheit
*/
float DHT::convertCtoF(float c) { return c * 1.8 + 32; }
float DHT::convertFtoC(float f) { /*!
return (f - 32) * 0.55555; * @brief Converts Fahrenheit to Celcius
} * @param f
* value in Fahrenheit
* @return float value in Celcius
*/
float DHT::convertFtoC(float f) { return (f - 32) * 0.55555; }
/*!
* @brief Read Humidity
* @param force
* force read mode
* @return float value - humidity in percent
*/
float DHT::readHumidity(bool force) { float DHT::readHumidity(bool force) {
float f = NAN; float f = NAN;
if (read(force)) { if (read(force)) {
@ -103,29 +160,44 @@ float DHT::readHumidity(bool force) {
return f; return f;
} }
//boolean isFahrenheit: True == Fahrenheit; False == Celcius /*!
* @brief Compute Heat Index
* Simplified version that reads temp and humidity from sensor
* @param isFahrenheit
* true if fahrenheit, false if celcius (default
*true)
* @return float heat index
*/
float DHT::computeHeatIndex(bool isFahrenheit) { float DHT::computeHeatIndex(bool isFahrenheit) {
float hi = computeHeatIndex(readTemperature(isFahrenheit), readHumidity(), float hi = computeHeatIndex(readTemperature(isFahrenheit), readHumidity(),
isFahrenheit); isFahrenheit);
return hi; return hi;
} }
//boolean isFahrenheit: True == Fahrenheit; False == Celcius /*!
* @brief Compute Heat Index
* Using both Rothfusz and Steadman's equations
* (http://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml)
* @param temperature
* temperature in selected scale
* @param percentHumidity
* humidity in percent
* @param isFahrenheit
* true if fahrenheit, false if celcius
* @return float heat index
*/
float DHT::computeHeatIndex(float temperature, float percentHumidity, float DHT::computeHeatIndex(float temperature, float percentHumidity,
bool isFahrenheit) { bool isFahrenheit) {
// Using both Rothfusz and Steadman's equations
// http://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml
float hi; float hi;
if (!isFahrenheit) if (!isFahrenheit)
temperature = convertCtoF(temperature); temperature = convertCtoF(temperature);
hi = 0.5 * (temperature + 61.0 + ((temperature - 68.0) * 1.2) + (percentHumidity * 0.094)); hi = 0.5 * (temperature + 61.0 + ((temperature - 68.0) * 1.2) +
(percentHumidity * 0.094));
if (hi > 79) { if (hi > 79) {
hi = -42.379 + hi = -42.379 + 2.04901523 * temperature + 10.14333127 * percentHumidity +
2.04901523 * temperature +
10.14333127 * percentHumidity +
-0.22475541 * temperature * percentHumidity + -0.22475541 * temperature * percentHumidity +
-0.00683783 * pow(temperature, 2) + -0.00683783 * pow(temperature, 2) +
-0.05481717 * pow(percentHumidity, 2) + -0.05481717 * pow(percentHumidity, 2) +
@ -133,16 +205,26 @@ float DHT::computeHeatIndex(float temperature, float percentHumidity,
0.00085282 * temperature * pow(percentHumidity, 2) + 0.00085282 * temperature * pow(percentHumidity, 2) +
-0.00000199 * pow(temperature, 2) * pow(percentHumidity, 2); -0.00000199 * pow(temperature, 2) * pow(percentHumidity, 2);
if((percentHumidity < 13) && (temperature >= 80.0) && (temperature <= 112.0)) if ((percentHumidity < 13) && (temperature >= 80.0) &&
hi -= ((13.0 - percentHumidity) * 0.25) * sqrt((17.0 - abs(temperature - 95.0)) * 0.05882); (temperature <= 112.0))
hi -= ((13.0 - percentHumidity) * 0.25) *
sqrt((17.0 - abs(temperature - 95.0)) * 0.05882);
else if((percentHumidity > 85.0) && (temperature >= 80.0) && (temperature <= 87.0)) else if ((percentHumidity > 85.0) && (temperature >= 80.0) &&
(temperature <= 87.0))
hi += ((percentHumidity - 85.0) * 0.1) * ((87.0 - temperature) * 0.2); hi += ((percentHumidity - 85.0) * 0.1) * ((87.0 - temperature) * 0.2);
} }
return isFahrenheit ? hi : convertFtoC(hi); return isFahrenheit ? hi : convertFtoC(hi);
} }
/*!
* @brief Read value from sensor or return last one from less than two
*seconds.
* @param force
* true if using force mode
* @return float value
*/
bool DHT::read(bool force) { bool DHT::read(bool force) {
// Check if sensor was read less than two seconds ago and return early // Check if sensor was read less than two seconds ago and return early
// to use last reading. // to use last reading.
@ -214,8 +296,8 @@ bool DHT::read(bool force) {
// then it's a 1. We measure the cycle count of the initial 50us low pulse // then it's a 1. We measure the cycle count of the initial 50us low pulse
// and use that to compare to the cycle count of the high pulse to determine // and use that to compare to the cycle count of the high pulse to determine
// if the bit is a 0 (high state cycle count < low state cycle count), or a // if the bit is a 0 (high state cycle count < low state cycle count), or a
// 1 (high state cycle count > low state cycle count). Note that for speed all // 1 (high state cycle count > low state cycle count). Note that for speed
// the pulses are read into a array and then examined in a later step. // all the pulses are read into a array and then examined in a later step.
for (int i = 0; i < 80; i += 2) { for (int i = 0; i < 80; i += 2) {
cycles[i] = expectPulse(LOW); cycles[i] = expectPulse(LOW);
cycles[i + 1] = expectPulse(HIGH); cycles[i + 1] = expectPulse(HIGH);
@ -244,19 +326,23 @@ bool DHT::read(bool force) {
} }
DEBUG_PRINTLN(F("Received from DHT:")); DEBUG_PRINTLN(F("Received from DHT:"));
DEBUG_PRINT(data[0], HEX); DEBUG_PRINT(F(", ")); DEBUG_PRINT(data[0], HEX);
DEBUG_PRINT(data[1], HEX); DEBUG_PRINT(F(", ")); DEBUG_PRINT(F(", "));
DEBUG_PRINT(data[2], HEX); DEBUG_PRINT(F(", ")); DEBUG_PRINT(data[1], HEX);
DEBUG_PRINT(data[3], HEX); DEBUG_PRINT(F(", ")); DEBUG_PRINT(F(", "));
DEBUG_PRINT(data[4], HEX); DEBUG_PRINT(F(" =? ")); DEBUG_PRINT(data[2], HEX);
DEBUG_PRINT(F(", "));
DEBUG_PRINT(data[3], HEX);
DEBUG_PRINT(F(", "));
DEBUG_PRINT(data[4], HEX);
DEBUG_PRINT(F(" =? "));
DEBUG_PRINTLN((data[0] + data[1] + data[2] + data[3]) & 0xFF, HEX); DEBUG_PRINTLN((data[0] + data[1] + data[2] + data[3]) & 0xFF, HEX);
// Check we read 40 bits and that the checksum matches. // Check we read 40 bits and that the checksum matches.
if (data[4] == ((data[0] + data[1] + data[2] + data[3]) & 0xFF)) { if (data[4] == ((data[0] + data[1] + data[2] + data[3]) & 0xFF)) {
_lastresult = true; _lastresult = true;
return _lastresult; return _lastresult;
} } else {
else {
DEBUG_PRINTLN(F("DHT checksum failure!")); DEBUG_PRINTLN(F("DHT checksum failure!"));
_lastresult = false; _lastresult = false;
return _lastresult; return _lastresult;
@ -285,8 +371,8 @@ uint32_t DHT::expectPulse(bool level) {
return TIMEOUT; // Exceeded timeout, fail. return TIMEOUT; // Exceeded timeout, fail.
} }
} }
// Otherwise fall back to using digitalRead (this seems to be necessary on ESP8266 // Otherwise fall back to using digitalRead (this seems to be necessary on
// right now, perhaps bugs in direct port access functions?). // ESP8266 right now, perhaps bugs in direct port access functions?).
#else #else
while (digitalRead(_pin) == level) { while (digitalRead(_pin) == level) {
if (count++ >= _maxcycles) { if (count++ >= _maxcycles) {

55
DHT.h
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@ -1,41 +1,49 @@
/* DHT library /*!
* @file DHT.h
MIT license *
written by Adafruit Industries * This is a library for DHT series of low cost temperature/humidity sensors.
*
* You must have Adafruit Unified Sensor Library library installed to use this class.
*
* Adafruit invests time and resources providing this open source code,
* please support Adafruit andopen-source hardware by purchasing products
* from Adafruit!
*
* Written by Adafruit Industries.
*
* MIT license, all text above must be included in any redistribution
*/ */
#ifndef DHT_H #ifndef DHT_H
#define DHT_H #define DHT_H
#if ARDUINO >= 100
#include "Arduino.h" #include "Arduino.h"
#else
#include "WProgram.h"
#endif
/* Uncomment to enable printing out nice debug messages. */
// Uncomment to enable printing out nice debug messages.
//#define DHT_DEBUG //#define DHT_DEBUG
// Define where debug output will be printed.
#define DEBUG_PRINTER Serial
// Setup debug printing macros. #define DEBUG_PRINTER Serial /**< Define where debug output will be printed. */
/* Setup debug printing macros. */
#ifdef DHT_DEBUG #ifdef DHT_DEBUG
#define DEBUG_PRINT(...) { DEBUG_PRINTER.print(__VA_ARGS__); } #define DEBUG_PRINT(...) { DEBUG_PRINTER.print(__VA_ARGS__); }
#define DEBUG_PRINTLN(...) { DEBUG_PRINTER.println(__VA_ARGS__); } #define DEBUG_PRINTLN(...) { DEBUG_PRINTER.println(__VA_ARGS__); }
#else #else
#define DEBUG_PRINT(...) {} #define DEBUG_PRINT(...) {} /**< Debug Print Placeholder if Debug is disabled */
#define DEBUG_PRINTLN(...) {} #define DEBUG_PRINTLN(...) {} /**< Debug Print Line Placeholder if Debug is disabled */
#endif #endif
// Define types of sensors. /* Define types of sensors. */
#define DHT11 11 #define DHT11 11 /**< DHT TYPE 11 */
#define DHT12 12 #define DHT12 12 /**< DHY TYPE 12 */
#define DHT22 22 #define DHT22 22 /**< DHT TYPE 22 */
#define DHT21 21 #define DHT21 21 /**< DHT TYPE 21 */
#define AM2301 21 #define AM2301 21 /**< AM2301 */
/*!
* @brief Class that stores state and functions for DHT
*/
class DHT { class DHT {
public: public:
DHT(uint8_t pin, uint8_t type, uint8_t count=6); DHT(uint8_t pin, uint8_t type, uint8_t count=6);
@ -64,6 +72,9 @@ class DHT {
}; };
/*!
* @brief Class that defines Interrupt Lock Avaiability
*/
class InterruptLock { class InterruptLock {
public: public:
InterruptLock() { InterruptLock() {

77
DHT_U.h
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@ -1,37 +1,56 @@
// DHT Temperature & Humidity Unified Sensor Library /*!
// Copyright (c) 2014 Adafruit Industries * @file DHT_U.h
// Author: Tony DiCola *
* DHT Temperature & Humidity Unified Sensor Library<Paste>
*
* Adafruit invests time and resources providing this open source code,
* please support Adafruit andopen-source hardware by purchasing products
* from Adafruit!
*
* Written by Tony DiCola (Adafruit Industries) 2014.
*
* MIT license, all text above must be included in any redistribution
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#ifndef DHT_U_H #ifndef DHT_U_H
#define DHT_U_H #define DHT_U_H
#include <Adafruit_Sensor.h> #include <Adafruit_Sensor.h>
#include <DHT.h> #include <DHT.h>
#define DHT_SENSOR_VERSION 1 #define DHT_SENSOR_VERSION 1 /**< Sensor Version */
/*!
* @brief Class that stores state and functions for interacting with
* DHT_Unified.
*/
class DHT_Unified { class DHT_Unified {
public: public:
DHT_Unified(uint8_t pin, uint8_t type, uint8_t count=6, int32_t tempSensorId=-1, int32_t humiditySensorId=-1); DHT_Unified(uint8_t pin, uint8_t type, uint8_t count = 6,
int32_t tempSensorId = -1, int32_t humiditySensorId = -1);
void begin(); void begin();
/*!
* @brief Class that stores state and functions about Temperature
*/
class Temperature : public Adafruit_Sensor { class Temperature : public Adafruit_Sensor {
public: public:
Temperature(DHT_Unified *parent, int32_t id); Temperature(DHT_Unified *parent, int32_t id);
@ -41,9 +60,11 @@ public:
private: private:
DHT_Unified *_parent; DHT_Unified *_parent;
int32_t _id; int32_t _id;
}; };
/*!
* @brief Class that stores state and functions about Humidity
*/
class Humidity : public Adafruit_Sensor { class Humidity : public Adafruit_Sensor {
public: public:
Humidity(DHT_Unified *parent, int32_t id); Humidity(DHT_Unified *parent, int32_t id);
@ -53,16 +74,11 @@ public:
private: private:
DHT_Unified *_parent; DHT_Unified *_parent;
int32_t _id; int32_t _id;
}; };
Temperature temperature() { Temperature temperature() { return _temp; }
return _temp;
}
Humidity humidity() { Humidity humidity() { return _humidity; }
return _humidity;
}
private: private:
DHT _dht; DHT _dht;
@ -72,7 +88,6 @@ private:
void setName(sensor_t *sensor); void setName(sensor_t *sensor);
void setMinDelay(sensor_t *sensor); void setMinDelay(sensor_t *sensor);
}; };
#endif #endif