Update library.properties

doxygen + readme + cleanups

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,46 @@
+Thank you for opening an issue on an Adafruit Arduino library repository.  To
+improve the speed of resolution please review the following guidelines and
+common troubleshooting steps below before creating the issue:
+
+- **Do not use GitHub issues for troubleshooting projects and issues.**  Instead use
+  the forums at http://forums.adafruit.com to ask questions and troubleshoot why
+  something isn't working as expected.  In many cases the problem is a common issue
+  that you will more quickly receive help from the forum community.  GitHub issues
+  are meant for known defects in the code.  If you don't know if there is a defect
+  in the code then start with troubleshooting on the forum first.
+
+- **If following a tutorial or guide be sure you didn't miss a step.** Carefully
+  check all of the steps and commands to run have been followed.  Consult the
+  forum if you're unsure or have questions about steps in a guide/tutorial.
+
+- **For Arduino projects check these very common issues to ensure they don't apply**:
+
+  - For uploading sketches or communicating with the board make sure you're using
+    a **USB data cable** and **not** a **USB charge-only cable**.  It is sometimes
+    very hard to tell the difference between a data and charge cable!  Try using the
+    cable with other devices or swapping to another cable to confirm it is not
+    the problem.
+
+  - **Be sure you are supplying adequate power to the board.**  Check the specs of
+    your board and plug in an external power supply.  In many cases just
+    plugging a board into your computer is not enough to power it and other
+    peripherals.
+
+  - **Double check all soldering joints and connections.**  Flakey connections
+    cause many mysterious problems.  See the [guide to excellent soldering](https://learn.adafruit.com/adafruit-guide-excellent-soldering/tools) for examples of good solder joints.
+
+  - **Ensure you are using an official Arduino or Adafruit board.** We can't
+    guarantee a clone board will have the same functionality and work as expected
+    with this code and don't support them.
+
+If you're sure this issue is a defect in the code and checked the steps above
+please fill in the following fields to provide enough troubleshooting information.
+You may delete the guideline and text above to just leave the following details:
+
+- Arduino board:  **INSERT ARDUINO BOARD NAME/TYPE HERE**
+
+- Arduino IDE version (found in Arduino -> About Arduino menu):  **INSERT ARDUINO
+  VERSION HERE**
+
+- List the steps to reproduce the problem below (if possible attach a sketch or
+  copy the sketch code in too): **LIST REPRO STEPS BELOW**

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,26 @@
+Thank you for creating a pull request to contribute to Adafruit's GitHub code!
+Before you open the request please review the following guidelines and tips to
+help it be more easily integrated:
+
+- **Describe the scope of your change--i.e. what the change does and what parts
+  of the code were modified.**  This will help us understand any risks of integrating
+  the code.
+
+- **Describe any known limitations with your change.**  For example if the change
+  doesn't apply to a supported platform of the library please mention it.
+
+- **Please run any tests or examples that can exercise your modified code.**  We
+  strive to not break users of the code and running tests/examples helps with this
+  process.
+
+Thank you again for contributing!  We will try to test and integrate the change
+as soon as we can, but be aware we have many GitHub repositories to manage and
+can't immediately respond to every request.  There is no need to bump or check in
+on a pull request (it will clutter the discussion of the request).
+
+Also don't be worried if the request is closed or not integrated--sometimes the
+priorities of Adafruit's GitHub code (education, ease of use) might not match the
+priorities of the pull request.  Don't fret, the open source community thrives on
+forks and GitHub makes it easy to keep your changes in a forked repo.
+
+After reviewing the guidelines above you can delete this text from the pull request.

.gitignore

@@ -0,0 +1,8 @@
+# osx
+.DS_Store
+
+# doxygen
+Doxyfile*
+doxygen_sqlite3.db
+html
+*.tmp

.travis.yml

@@ -0,0 +1,29 @@
+language: c
+sudo: false
+
+cache:
+  directories:
+    - ~/arduino_ide
+    - ~/.arduino15/packages/
+
+git:
+  depth: false
+  quiet: true
+
+env:
+  global:
+    - ARDUINO_IDE_VERSION="1.8.7"
+    - PRETTYNAME="DHT sensor library"
+
+before_install:
+  - source <(curl -SLs https://raw.githubusercontent.com/adafruit/travis-ci-arduino/master/install.sh)
+
+install:
+  - arduino --install-library "Adafruit Unified Sensor"
+
+script:
+  - build_main_platforms
+
+after_success:
+  - source <(curl -SLs https://raw.githubusercontent.com/adafruit/travis-ci-arduino/master/library_check.sh)
+  - source <(curl -SLs https://raw.githubusercontent.com/adafruit/travis-ci-arduino/master/doxy_gen_and_deploy.sh)

DHT.cpp

@@ -1,53 +1,117 @@
-/* DHT library
-
-MIT license
-written by Adafruit Industries
-*/
+/*!
+ *  @file DHT.cpp
+ *
+ *  @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"
 
+#define MIN_INTERVAL 2000 /**< min interval value */
+#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) {
   _pin = pin;
   _type = type;
-  _firstreading = true;
+#ifdef __AVR
   _bit = digitalPinToBitMask(pin);
   _port = digitalPinToPort(pin);
-  _maxcycles = microsecondsToClockCycles(1000);  // 1 millisecond timeout for
-                                                 // reading pulses from DHT sensor.
+#endif
+  _maxcycles =
+      microsecondsToClockCycles(1000); // 1 millisecond timeout for
+                                       // reading pulses from DHT sensor.
   // Note that count is now ignored as the DHT reading algorithm adjusts itself
-  // basd on the speed of the processor.
+  // based on the speed of the processor.
 }
 
-void DHT::begin(void) {
+/*!
+ *  @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) {
   // set up the pins!
-  pinMode(_pin, INPUT);
-  digitalWrite(_pin, HIGH);
-  _lastreadtime = 0;
-  DEBUG_PRINT("Max clock cycles: "); DEBUG_PRINTLN(_maxcycles, DEC);
+  pinMode(_pin, INPUT_PULLUP);
+  // Using this value makes sure that millis() - lastreadtime will be
+  // >= MIN_INTERVAL right away. Note that this assignment wraps around,
+  // but so will the subtraction.
+  _lastreadtime = millis() - MIN_INTERVAL;
+  DEBUG_PRINT("DHT max clock cycles: ");
+  DEBUG_PRINTLN(_maxcycles, DEC);
+  pullTime = usec;
 }
 
-//boolean S == Scale.  True == Fahrenheit; False == Celcius
-float DHT::readTemperature(bool S) {
+/*!
+ *  @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 f = NAN;
 
-  if (read()) {
+  if (read(force)) {
     switch (_type) {
     case DHT11:
       f = data[2];
-      if(S) {
+      if (data[3] & 0x80) {
+        f = -1 - f;
+      }
+      f += (data[3] & 0x0f) * 0.1;
+      if (S) {
         f = convertCtoF(f);
       }
       break;
-    case DHT22:
-    case DHT21:
-      f = data[2] & 0x7F;
-      f *= 256;
-      f += data[3];
-      f /= 10;
+    case DHT12:
+      f = data[2];
+      f += (data[3] & 0x0f) * 0.1;
       if (data[2] & 0x80) {
         f *= -1;
       }
-      if(S) {
+      if (S) {
+        f = convertCtoF(f);
+      }
+      break;
+    case DHT22:
+    case DHT21:
+      f = ((word)(data[2] & 0x7F)) << 8 | data[3];
+      f *= 0.1;
+      if (data[2] & 0x80) {
+        f *= -1;
+      }
+      if (S) {
         f = convertCtoF(f);
       }
       break;
@@ -56,116 +120,172 @@ float DHT::readTemperature(bool S) {
   return f;
 }
 
-float DHT::convertCtoF(float c) {
-  return c * 9 / 5 + 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) * 5 / 9;
-}
+/*!
+ *  @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; }
 
-float DHT::readHumidity(void) {
+/*!
+ *  @brief  Read Humidity
+ *  @param  force
+ *					force read mode
+ *	@return float value - humidity in percent
+ */
+float DHT::readHumidity(bool force) {
   float f = NAN;
-  if (read()) {
+  if (read(force)) {
     switch (_type) {
     case DHT11:
-      f = data[0];
+    case DHT12:
+      f = data[0] + data[1] * 0.1;
       break;
     case DHT22:
     case DHT21:
-      f = data[0];
-      f *= 256;
-      f += data[1];
-      f /= 10;
+      f = ((word)data[0]) << 8 | data[1];
+      f *= 0.1;
       break;
     }
   }
   return f;
 }
 
-//boolean isFahrenheit: True == Fahrenheit; False == Celcius
-float DHT::computeHeatIndex(float temperature, float percentHumidity, bool isFahrenheit) {
-  // Adapted from equation at: https://github.com/adafruit/DHT-sensor-library/issues/9 and
-  // Wikipedia: http://en.wikipedia.org/wiki/Heat_index
-  if (!isFahrenheit) {
-    // Celsius heat index calculation.
-    return -8.784695 +
-             1.61139411 * temperature +
-             2.338549   * percentHumidity +
-            -0.14611605 * temperature*percentHumidity +
-            -0.01230809 * pow(temperature, 2) +
-            -0.01642482 * pow(percentHumidity, 2) +
-             0.00221173 * pow(temperature, 2) * percentHumidity +
-             0.00072546 * temperature*pow(percentHumidity, 2) +
-            -0.00000358 * pow(temperature, 2) * pow(percentHumidity, 2);
-  }
-  else {
-    // Fahrenheit heat index calculation.
-    return -42.379 +
-             2.04901523 * temperature +
-            10.14333127 * percentHumidity +
-            -0.22475541 * temperature*percentHumidity +
-            -0.00683783 * pow(temperature, 2) +
-            -0.05481717 * pow(percentHumidity, 2) +
-             0.00122874 * pow(temperature, 2) * percentHumidity +
-             0.00085282 * temperature*pow(percentHumidity, 2) +
-            -0.00000199 * pow(temperature, 2) * pow(percentHumidity, 2);
-  }
+/*!
+ *  @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 hi = computeHeatIndex(readTemperature(isFahrenheit), readHumidity(),
+                              isFahrenheit);
+  return hi;
 }
 
-boolean DHT::read(void) {
+/*!
+ *  @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,
+                            bool isFahrenheit) {
+  float hi;
+
+  if (!isFahrenheit)
+    temperature = convertCtoF(temperature);
+
+  hi = 0.5 * (temperature + 61.0 + ((temperature - 68.0) * 1.2) +
+              (percentHumidity * 0.094));
+
+  if (hi > 79) {
+    hi = -42.379 + 2.04901523 * temperature + 10.14333127 * percentHumidity +
+         -0.22475541 * temperature * percentHumidity +
+         -0.00683783 * pow(temperature, 2) +
+         -0.05481717 * pow(percentHumidity, 2) +
+         0.00122874 * pow(temperature, 2) * percentHumidity +
+         0.00085282 * temperature * pow(percentHumidity, 2) +
+         -0.00000199 * pow(temperature, 2) * pow(percentHumidity, 2);
+
+    if ((percentHumidity < 13) && (temperature >= 80.0) &&
+        (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))
+      hi += ((percentHumidity - 85.0) * 0.1) * ((87.0 - temperature) * 0.2);
+  }
+
+  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) {
   // Check if sensor was read less than two seconds ago and return early
   // to use last reading.
   uint32_t currenttime = millis();
-  if (currenttime < _lastreadtime) {
-    // ie there was a rollover
-    _lastreadtime = 0;
-  }
-  if (!_firstreading && ((currenttime - _lastreadtime) < 2000)) {
+  if (!force && ((currenttime - _lastreadtime) < MIN_INTERVAL)) {
     return _lastresult; // return last correct measurement
   }
-  _firstreading = false;
-  _lastreadtime = millis();
+  _lastreadtime = currenttime;
 
   // Reset 40 bits of received data to zero.
   data[0] = data[1] = data[2] = data[3] = data[4] = 0;
 
+#if defined(ESP8266)
+  yield(); // Handle WiFi / reset software watchdog
+#endif
+
   // Send start signal.  See DHT datasheet for full signal diagram:
   //   http://www.adafruit.com/datasheets/Digital%20humidity%20and%20temperature%20sensor%20AM2302.pdf
 
   // Go into high impedence state to let pull-up raise data line level and
   // start the reading process.
-  digitalWrite(_pin, HIGH);
-  delay(250);
+  pinMode(_pin, INPUT_PULLUP);
+  delay(1);
 
-  // First set data line low for 20 milliseconds.
+  // First set data line low for a period according to sensor type
   pinMode(_pin, OUTPUT);
   digitalWrite(_pin, LOW);
-  delay(20);
+  switch (_type) {
+  case DHT22:
+  case DHT21:
+    delayMicroseconds(1100); // data sheet says "at least 1ms"
+    break;
+  case DHT11:
+  default:
+    delay(20); // data sheet says at least 18ms, 20ms just to be safe
+    break;
+  }
 
   uint32_t cycles[80];
   {
-    // Turn off interrupts temporarily because the next sections are timing critical
-    // and we don't want any interruptions.
-    InterruptLock lock;
-
     // End the start signal by setting data line high for 40 microseconds.
-    digitalWrite(_pin, HIGH);
-    delayMicroseconds(40);
+    pinMode(_pin, INPUT_PULLUP);
+
+    // Delay a moment to let sensor pull data line low.
+    delayMicroseconds(pullTime);
 
     // Now start reading the data line to get the value from the DHT sensor.
-    pinMode(_pin, INPUT);
-    delayMicroseconds(10);  // Delay a bit to let sensor pull data line low.
+
+    // Turn off interrupts temporarily because the next sections
+    // are timing critical and we don't want any interruptions.
+    InterruptLock lock;
 
     // First expect a low signal for ~80 microseconds followed by a high signal
     // for ~80 microseconds again.
-    if (expectPulse(LOW) == 0) {
-      DEBUG_PRINTLN(F("Timeout waiting for start signal low pulse."));
+    if (expectPulse(LOW) == TIMEOUT) {
+      DEBUG_PRINTLN(F("DHT timeout waiting for start signal low pulse."));
       _lastresult = false;
       return _lastresult;
     }
-    if (expectPulse(HIGH) == 0) {
-      DEBUG_PRINTLN(F("Timeout waiting for start signal high pulse."));
+    if (expectPulse(HIGH) == TIMEOUT) {
+      DEBUG_PRINTLN(F("DHT timeout waiting for start signal high pulse."));
       _lastresult = false;
       return _lastresult;
     }
@@ -176,50 +296,54 @@ boolean DHT::read(void) {
     // 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
     // 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
-    // the pulses are read into a array and then examined in a later step.
-    for (int i=0; i<80; i+=2) {
-      cycles[i]   = expectPulse(LOW);
-      cycles[i+1] = expectPulse(HIGH);
+    // 1 (high state cycle count > low state cycle count). Note that for speed
+    // all the pulses are read into a array and then examined in a later step.
+    for (int i = 0; i < 80; i += 2) {
+      cycles[i] = expectPulse(LOW);
+      cycles[i + 1] = expectPulse(HIGH);
     }
   } // Timing critical code is now complete.
 
   // Inspect pulses and determine which ones are 0 (high state cycle count < low
   // state cycle count), or 1 (high state cycle count > low state cycle count).
-  for (int i=0; i<40; ++i) {
-    uint32_t lowCycles  = cycles[2*i];
-    uint32_t highCycles = cycles[2*i+1];
-    if ((lowCycles == 0) || (highCycles == 0)) {
-      DEBUG_PRINTLN(F("Timeout waiting for pulse."));
+  for (int i = 0; i < 40; ++i) {
+    uint32_t lowCycles = cycles[2 * i];
+    uint32_t highCycles = cycles[2 * i + 1];
+    if ((lowCycles == TIMEOUT) || (highCycles == TIMEOUT)) {
+      DEBUG_PRINTLN(F("DHT timeout waiting for pulse."));
       _lastresult = false;
       return _lastresult;
     }
-    data[i/8] <<= 1;
+    data[i / 8] <<= 1;
     // Now compare the low and high cycle times to see if the bit is a 0 or 1.
     if (highCycles > lowCycles) {
       // High cycles are greater than 50us low cycle count, must be a 1.
-      data[i/8] |= 1;
+      data[i / 8] |= 1;
     }
     // Else high cycles are less than (or equal to, a weird case) the 50us low
     // cycle count so this must be a zero.  Nothing needs to be changed in the
     // stored data.
   }
 
-  DEBUG_PRINTLN(F("Received:"));
-  DEBUG_PRINT(data[0], HEX); DEBUG_PRINT(F(", "));
-  DEBUG_PRINT(data[1], 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(F("Received from DHT:"));
+  DEBUG_PRINT(data[0], HEX);
+  DEBUG_PRINT(F(", "));
+  DEBUG_PRINT(data[1], 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);
 
   // Check we read 40 bits and that the checksum matches.
   if (data[4] == ((data[0] + data[1] + data[2] + data[3]) & 0xFF)) {
     _lastresult = true;
     return _lastresult;
-  }
-  else {
-    DEBUG_PRINTLN(F("Checksum failure!"));
+  } else {
+    DEBUG_PRINTLN(F("DHT checksum failure!"));
     _lastresult = false;
     return _lastresult;
   }
@@ -233,25 +357,29 @@ boolean DHT::read(void) {
 // in the very latest IDE versions):
 //   https://github.com/arduino/Arduino/blob/master/hardware/arduino/avr/cores/arduino/wiring_pulse.c
 uint32_t DHT::expectPulse(bool level) {
+#if (F_CPU > 16000000L)
   uint32_t count = 0;
-  // On AVR platforms use direct GPIO port access as it's much faster and better
-  // for catching pulses that are 10's of microseconds in length:
-  #ifdef __AVR
-    uint8_t portState = level ? _bit : 0;
-    while ((*portInputRegister(_port) & _bit) == portState) {
-      if (count++ >= _maxcycles) {
-        return 0; // Exceeded timeout, fail.
-      }
+#else
+  uint16_t count = 0; // To work fast enough on slower AVR boards
+#endif
+// On AVR platforms use direct GPIO port access as it's much faster and better
+// for catching pulses that are 10's of microseconds in length:
+#ifdef __AVR
+  uint8_t portState = level ? _bit : 0;
+  while ((*portInputRegister(_port) & _bit) == portState) {
+    if (count++ >= _maxcycles) {
+      return TIMEOUT; // Exceeded timeout, fail.
     }
-  // Otherwise fall back to using digitalRead (this seems to be necessary on ESP8266
-  // right now, perhaps bugs in direct port access functions?).
-  #else
-    while (digitalRead(_pin) == level) {
-      if (count++ >= _maxcycles) {
-        return 0; // Exceeded timeout, fail.
-      }
+  }
+// Otherwise fall back to using digitalRead (this seems to be necessary on
+// ESP8266 right now, perhaps bugs in direct port access functions?).
+#else
+  while (digitalRead(_pin) == level) {
+    if (count++ >= _maxcycles) {
+      return TIMEOUT; // Exceeded timeout, fail.
     }
-  #endif
+  }
+#endif
 
   return count;
 }

DHT.h

@@ -1,71 +1,92 @@
-/* DHT library
+/*!
+ *  @file DHT.h
+ *
+ *  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
+ */
 
-MIT license
-written by Adafruit Industries
-*/
 #ifndef DHT_H
 #define DHT_H
 
-#if ARDUINO >= 100
- #include "Arduino.h"
-#else
- #include "WProgram.h"
-#endif
+#include "Arduino.h"
 
-
-// Uncomment to enable printing out nice debug messages.
+/* Uncomment to enable printing out nice debug messages. */
 //#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
   #define DEBUG_PRINT(...) { DEBUG_PRINTER.print(__VA_ARGS__); }
   #define DEBUG_PRINTLN(...) { DEBUG_PRINTER.println(__VA_ARGS__); }
 #else
-  #define DEBUG_PRINT(...) {}
-  #define DEBUG_PRINTLN(...) {}
+  #define DEBUG_PRINT(...) {} /**< Debug Print Placeholder if Debug is disabled */
+  #define DEBUG_PRINTLN(...) {} /**< Debug Print Line Placeholder if Debug is disabled */
 #endif
 
-// Define types of sensors.
-#define DHT11 11
-#define DHT22 22
-#define DHT21 21
-#define AM2301 21
-
+/* Define types of sensors. */
+#define DHT11 11 /**< DHT TYPE 11 */
+#define DHT12 12 /**< DHY TYPE 12 */
+#define DHT22 22 /**< DHT TYPE 22 */
+#define DHT21 21 /**< DHT TYPE 21 */
+#define AM2301 21 /**< AM2301 */
 
+/*! 
+ *  @brief  Class that stores state and functions for DHT
+ */
 class DHT {
   public:
    DHT(uint8_t pin, uint8_t type, uint8_t count=6);
-   void begin(void);
-   float readTemperature(bool S=false);
+   void begin(uint8_t usec=55);
+   float readTemperature(bool S=false, bool force=false);
    float convertCtoF(float);
    float convertFtoC(float);
+   float computeHeatIndex(bool isFahrenheit=true);
    float computeHeatIndex(float temperature, float percentHumidity, bool isFahrenheit=true);
-   float readHumidity(void);
-   boolean read(void);
+   float readHumidity(bool force=false);
+   bool read(bool force=false);
 
  private:
-  uint8_t data[6];
-  uint8_t _pin, _type, _bit, _port;
+  uint8_t data[5];
+  uint8_t _pin, _type;
+  #ifdef __AVR
+    // Use direct GPIO access on an 8-bit AVR so keep track of the port and bitmask
+    // for the digital pin connected to the DHT.  Other platforms will use digitalRead.
+    uint8_t _bit, _port;
+  #endif
   uint32_t _lastreadtime, _maxcycles;
-  bool _firstreading;
   bool _lastresult;
+  uint8_t pullTime; // Time (in usec) to pull up data line before reading
 
   uint32_t expectPulse(bool level);
 
 };
 
+/*! 
+ *  @brief  Class that defines Interrupt Lock Avaiability
+ */
 class InterruptLock {
   public:
    InterruptLock() {
+#if !defined(ARDUINO_ARCH_NRF52)  
     noInterrupts();
+#endif
    }
    ~InterruptLock() {
+#if !defined(ARDUINO_ARCH_NRF52)  
     interrupts();
+#endif
    }
-
 };
 
 #endif

DHT_U.cpp

@@ -0,0 +1,246 @@
+/*!
+ *  @file DHT_U.cpp
+ *
+ *  Temperature & Humidity Unified Sensor Library
+ *
+ *  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!
+ */
+#include "DHT_U.h"
+
+/*!
+ *  @brief  Instantiates a new DHT_Unified class
+ *  @param  pin
+ *          pin number that sensor is connected
+ *  @param  type
+ *          type of sensor
+ *  @param  count
+ *          number of sensors
+ *  @param  tempSensorId
+ *          temperature sensor id
+ *  @param  humiditySensorId
+ *          humidity sensor id
+ */
+DHT_Unified::DHT_Unified(uint8_t pin, uint8_t type, uint8_t count, int32_t tempSensorId, int32_t humiditySensorId):
+  _dht(pin, type, count),
+  _type(type),
+  _temp(this, tempSensorId),
+  _humidity(this, humiditySensorId)
+{}
+
+/*!
+ *  @brief  Setup sensor (calls begin on It)
+ */
+void DHT_Unified::begin() {
+  _dht.begin();
+}
+
+/*!
+ *  @brief  Sets sensor name
+ *  @param  sensor
+ *          Sensor that will be set
+ */
+void DHT_Unified::setName(sensor_t* sensor) {
+  switch(_type) {
+    case DHT11:
+      strncpy(sensor->name, "DHT11", sizeof(sensor->name) - 1);
+      break;
+    case DHT12:
+      strncpy(sensor->name, "DHT12", sizeof(sensor->name) - 1);
+      break;
+    case DHT21:
+      strncpy(sensor->name, "DHT21", sizeof(sensor->name) - 1);
+      break;
+    case DHT22:
+      strncpy(sensor->name, "DHT22", sizeof(sensor->name) - 1);
+      break;
+    default:
+      // TODO: Perhaps this should be an error?  However main DHT library doesn't enforce
+      // restrictions on the sensor type value.  Pick a generic name for now.
+      strncpy(sensor->name, "DHT?", sizeof(sensor->name) - 1);
+      break;
+  }
+  sensor->name[sizeof(sensor->name)- 1] = 0;
+}
+
+/*!
+ *  @brief  Sets Minimum Delay Value
+ *  @param  sensor
+ *          Sensor that will be set
+ */
+void DHT_Unified::setMinDelay(sensor_t* sensor) {
+  switch(_type) {
+    case DHT11:
+      sensor->min_delay = 1000000L;  // 1 second (in microseconds)
+      break;
+    case DHT12:
+      sensor->min_delay = 2000000L;  // 2 second (in microseconds)
+      break;
+    case DHT21:
+      sensor->min_delay = 2000000L;  // 2 seconds (in microseconds)
+      break;
+    case DHT22:
+      sensor->min_delay = 2000000L;  // 2 seconds (in microseconds)
+      break;
+    default:
+      // Default to slowest sample rate in case of unknown type.
+      sensor->min_delay = 2000000L;  // 2 seconds (in microseconds)
+      break;
+  }
+}
+
+/*!
+ *  @brief  Instantiates a new DHT_Unified Temperature Class
+ *  @param  parent
+ *          Parent Sensor
+ *  @param  id
+ *          Sensor id
+ */
+DHT_Unified::Temperature::Temperature(DHT_Unified* parent, int32_t id):
+  _parent(parent),
+  _id(id)
+{}
+
+/*!
+ *  @brief  Reads the sensor and returns the data as a sensors_event_t
+ *  @param  event
+ *  @return always returns true
+ */
+bool DHT_Unified::Temperature::getEvent(sensors_event_t* event) {
+  // Clear event definition.
+  memset(event, 0, sizeof(sensors_event_t));
+  // Populate sensor reading values.
+  event->version     = sizeof(sensors_event_t);
+  event->sensor_id   = _id;
+  event->type        = SENSOR_TYPE_AMBIENT_TEMPERATURE;
+  event->timestamp   = millis();
+  event->temperature = _parent->_dht.readTemperature();
+  
+  return true;
+}
+
+/*!
+ *  @brief  Provides the sensor_t data for this sensor
+ *  @param  sensor
+ */
+void DHT_Unified::Temperature::getSensor(sensor_t* sensor) {
+  // Clear sensor definition.
+  memset(sensor, 0, sizeof(sensor_t));
+  // Set sensor name.
+  _parent->setName(sensor);
+  // Set version and ID
+  sensor->version         = DHT_SENSOR_VERSION;
+  sensor->sensor_id       = _id;
+  // Set type and characteristics.
+  sensor->type            = SENSOR_TYPE_AMBIENT_TEMPERATURE;
+  _parent->setMinDelay(sensor);
+  switch (_parent->_type) {
+    case DHT11:
+      sensor->max_value   = 50.0F;
+      sensor->min_value   = 0.0F;
+      sensor->resolution  = 2.0F;
+      break;
+    case DHT12:
+      sensor->max_value   = 60.0F;
+      sensor->min_value   = -20.0F;
+      sensor->resolution  = 0.5F;
+      break;
+    case DHT21:
+      sensor->max_value   = 80.0F;
+      sensor->min_value   = -40.0F;
+      sensor->resolution  = 0.1F;
+      break;
+    case DHT22:
+      sensor->max_value   = 125.0F;
+      sensor->min_value   = -40.0F;
+      sensor->resolution  = 0.1F;
+      break;
+    default:
+      // Unknown type, default to 0.
+      sensor->max_value   = 0.0F;
+      sensor->min_value   = 0.0F;
+      sensor->resolution  = 0.0F;
+      break;
+  }
+}
+
+/*!
+ *  @brief  Instantiates a new DHT_Unified Humidity Class
+ *  @param  parent
+ *          Parent Sensor
+ *  @param  id
+ *          Sensor id
+ */
+DHT_Unified::Humidity::Humidity(DHT_Unified* parent, int32_t id):
+  _parent(parent),
+  _id(id)
+{}
+
+/*!
+ *  @brief  Reads the sensor and returns the data as a sensors_event_t
+ *  @param  event
+ *  @return always returns true
+ */
+bool DHT_Unified::Humidity::getEvent(sensors_event_t* event) {
+  // Clear event definition.
+  memset(event, 0, sizeof(sensors_event_t));
+  // Populate sensor reading values.
+  event->version           = sizeof(sensors_event_t);
+  event->sensor_id         = _id;
+  event->type              = SENSOR_TYPE_RELATIVE_HUMIDITY;
+  event->timestamp         = millis();
+  event->relative_humidity = _parent->_dht.readHumidity();
+  
+  return true;
+}
+
+/*!
+ *  @brief  Provides the sensor_t data for this sensor
+ *  @param  sensor
+ */
+void DHT_Unified::Humidity::getSensor(sensor_t* sensor) {
+  // Clear sensor definition.
+  memset(sensor, 0, sizeof(sensor_t));
+  // Set sensor name.
+  _parent->setName(sensor);
+  // Set version and ID
+  sensor->version         = DHT_SENSOR_VERSION;
+  sensor->sensor_id       = _id;
+  // Set type and characteristics.
+  sensor->type            = SENSOR_TYPE_RELATIVE_HUMIDITY;
+  _parent->setMinDelay(sensor);
+  switch (_parent->_type) {
+    case DHT11:
+      sensor->max_value   = 80.0F;
+      sensor->min_value   = 20.0F;
+      sensor->resolution  = 5.0F;
+      break;
+    case DHT12:
+      sensor->max_value   = 95.0F;
+      sensor->min_value   = 20.0F;
+      sensor->resolution  = 5.0F;
+      break;
+    case DHT21:
+      sensor->max_value   = 100.0F;
+      sensor->min_value   = 0.0F;
+      sensor->resolution  = 0.1F;
+      break;
+    case DHT22:
+      sensor->max_value   = 100.0F;
+      sensor->min_value   = 0.0F;
+      sensor->resolution  = 0.1F;
+      break;
+    default:
+      // Unknown type, default to 0.
+      sensor->max_value   = 0.0F;
+      sensor->min_value   = 0.0F;
+      sensor->resolution  = 0.0F;
+      break;
+  }
+}

DHT_U.h

@@ -0,0 +1,101 @@
+/*!
+ *  @file DHT_U.h
+ *
+ *  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.
+ */
+
+#ifndef DHT_U_H
+#define DHT_U_H
+
+#include <Adafruit_Sensor.h>
+#include <DHT.h>
+
+#define DHT_SENSOR_VERSION 1 /**< Sensor Version */
+
+/*!
+ *  @brief  Class that stores state and functions for interacting with
+ * DHT_Unified.
+ */
+class DHT_Unified {
+public:
+  DHT_Unified(uint8_t pin, uint8_t type, uint8_t count = 6,
+              int32_t tempSensorId = -1, int32_t humiditySensorId = -1);
+  void begin();
+
+  /*!
+   *  @brief  Class that stores state and functions about Temperature
+   */
+  class Temperature : public Adafruit_Sensor {
+  public:
+    Temperature(DHT_Unified *parent, int32_t id);
+    bool getEvent(sensors_event_t *event);
+    void getSensor(sensor_t *sensor);
+
+  private:
+    DHT_Unified *_parent;
+    int32_t _id;
+  };
+
+  /*!
+   *  @brief  Class that stores state and functions about Humidity
+   */
+  class Humidity : public Adafruit_Sensor {
+  public:
+    Humidity(DHT_Unified *parent, int32_t id);
+    bool getEvent(sensors_event_t *event);
+    void getSensor(sensor_t *sensor);
+
+  private:
+    DHT_Unified *_parent;
+    int32_t _id;
+  };
+
+	/*!
+   *  @brief  Returns temperature stored in _temp
+   *  @return Temperature value
+   */
+  Temperature temperature() { return _temp; }
+
+	/*!
+   *  @brief  Returns humidity stored in _humidity
+   *  @return Humidity value
+   */
+  Humidity humidity() { return _humidity; }
+
+private:
+  DHT _dht;
+  uint8_t _type;
+  Temperature _temp;
+  Humidity _humidity;
+
+  void setName(sensor_t *sensor);
+  void setMinDelay(sensor_t *sensor);
+};
+
+#endif

README.md

@@ -0,0 +1,14 @@
+# Adafruit DHT Humidity & Temperature Sensor Library [![Build Status](https://travis-ci.org/adafruit/DHT-sensor-library.svg?branch=master)](https://travis-ci.org/adafruit/DHT-sensor-library)
+
+An Arduino library for the DHT series of low cost temperature/humidity sensors.
+
+Tutorial: https://learn.adafruit.com/dht
+
+**You must have the following Arduino libraries installed to use this class:**
+
+- [Adafruit Unified Sensor Library](https://github.com/adafruit/Adafruit_Sensor)
+
+Examples include both a "standalone" DHT example, and one that works along with the Adafruit Unified Sensor Library. Unified sensor library is required even if using the standalone version.
+
+Recent Arduino IDE releases include the Library Manager for easy installation. Otherwise, to download, click the DOWNLOADS button in the top right corner, rename the uncompressed folder DHT. Check that the DHT folder contains DHT.cpp and DHT.h. Place the DHT library folder your <arduinosketchfolder>/libraries/ folder. You may need to create the libraries subfolder if its your first library. Restart the IDE.
+

README.txt

@@ -1,3 +0,0 @@
-This is an Arduino library for the DHT series of low cost temperature/humidity sensors. 
-
-To download. click the DOWNLOADS button in the top right corner, rename the uncompressed folder DHT. Check that the DHT folder contains DHT.cpp and DHT.h. Place the DHT library folder your <arduinosketchfolder>/libraries/ folder. You may need to create the libraries subfolder if its your first library. Restart the IDE.

examples/DHT_Unified_Sensor/DHT_Unified_Sensor.ino

@@ -0,0 +1,85 @@
+// DHT Temperature & Humidity Sensor
+// Unified Sensor Library Example
+// Written by Tony DiCola for Adafruit Industries
+// Released under an MIT license.
+
+// REQUIRES the following Arduino libraries:
+// - DHT Sensor Library: https://github.com/adafruit/DHT-sensor-library
+// - Adafruit Unified Sensor Lib: https://github.com/adafruit/Adafruit_Sensor
+
+#include <Adafruit_Sensor.h>
+#include <DHT.h>
+#include <DHT_U.h>
+
+#define DHTPIN 2     // Digital pin connected to the DHT sensor 
+// Feather HUZZAH ESP8266 note: use pins 3, 4, 5, 12, 13 or 14 --
+// Pin 15 can work but DHT must be disconnected during program upload.
+
+// Uncomment the type of sensor in use:
+//#define DHTTYPE    DHT11     // DHT 11
+#define DHTTYPE    DHT22     // DHT 22 (AM2302)
+//#define DHTTYPE    DHT21     // DHT 21 (AM2301)
+
+// See guide for details on sensor wiring and usage:
+//   https://learn.adafruit.com/dht/overview
+
+DHT_Unified dht(DHTPIN, DHTTYPE);
+
+uint32_t delayMS;
+
+void setup() {
+  Serial.begin(9600);
+  // Initialize device.
+  dht.begin();
+  Serial.println(F("DHTxx Unified Sensor Example"));
+  // Print temperature sensor details.
+  sensor_t sensor;
+  dht.temperature().getSensor(&sensor);
+  Serial.println(F("------------------------------------"));
+  Serial.println(F("Temperature Sensor"));
+  Serial.print  (F("Sensor Type: ")); Serial.println(sensor.name);
+  Serial.print  (F("Driver Ver:  ")); Serial.println(sensor.version);
+  Serial.print  (F("Unique ID:   ")); Serial.println(sensor.sensor_id);
+  Serial.print  (F("Max Value:   ")); Serial.print(sensor.max_value); Serial.println(F("°C"));
+  Serial.print  (F("Min Value:   ")); Serial.print(sensor.min_value); Serial.println(F("°C"));
+  Serial.print  (F("Resolution:  ")); Serial.print(sensor.resolution); Serial.println(F("°C"));
+  Serial.println(F("------------------------------------"));
+  // Print humidity sensor details.
+  dht.humidity().getSensor(&sensor);
+  Serial.println(F("Humidity Sensor"));
+  Serial.print  (F("Sensor Type: ")); Serial.println(sensor.name);
+  Serial.print  (F("Driver Ver:  ")); Serial.println(sensor.version);
+  Serial.print  (F("Unique ID:   ")); Serial.println(sensor.sensor_id);
+  Serial.print  (F("Max Value:   ")); Serial.print(sensor.max_value); Serial.println(F("%"));
+  Serial.print  (F("Min Value:   ")); Serial.print(sensor.min_value); Serial.println(F("%"));
+  Serial.print  (F("Resolution:  ")); Serial.print(sensor.resolution); Serial.println(F("%"));
+  Serial.println(F("------------------------------------"));
+  // Set delay between sensor readings based on sensor details.
+  delayMS = sensor.min_delay / 1000;
+}
+
+void loop() {
+  // Delay between measurements.
+  delay(delayMS);
+  // Get temperature event and print its value.
+  sensors_event_t event;
+  dht.temperature().getEvent(&event);
+  if (isnan(event.temperature)) {
+    Serial.println(F("Error reading temperature!"));
+  }
+  else {
+    Serial.print(F("Temperature: "));
+    Serial.print(event.temperature);
+    Serial.println(F("°C"));
+  }
+  // Get humidity event and print its value.
+  dht.humidity().getEvent(&event);
+  if (isnan(event.relative_humidity)) {
+    Serial.println(F("Error reading humidity!"));
+  }
+  else {
+    Serial.print(F("Humidity: "));
+    Serial.print(event.relative_humidity);
+    Serial.println(F("%"));
+  }
+}

examples/DHTtester/DHTtester.ino

@@ -1,13 +1,19 @@
 // Example testing sketch for various DHT humidity/temperature sensors
 // Written by ladyada, public domain
 
+// REQUIRES the following Arduino libraries:
+// - DHT Sensor Library: https://github.com/adafruit/DHT-sensor-library
+// - Adafruit Unified Sensor Lib: https://github.com/adafruit/Adafruit_Sensor
+
 #include "DHT.h"
 
-#define DHTPIN 2     // what pin we're connected to
+#define DHTPIN 2     // Digital pin connected to the DHT sensor
+// Feather HUZZAH ESP8266 note: use pins 3, 4, 5, 12, 13 or 14 --
+// Pin 15 can work but DHT must be disconnected during program upload.
 
 // Uncomment whatever type you're using!
 //#define DHTTYPE DHT11   // DHT 11
-#define DHTTYPE DHT22   // DHT 22  (AM2302)
+#define DHTTYPE DHT22   // DHT 22  (AM2302), AM2321
 //#define DHTTYPE DHT21   // DHT 21 (AM2301)
 
 // Connect pin 1 (on the left) of the sensor to +5V
@@ -25,7 +31,7 @@ DHT dht(DHTPIN, DHTTYPE);
 
 void setup() {
   Serial.begin(9600);
-  Serial.println("DHTxx test!");
+  Serial.println(F("DHTxx test!"));
 
   dht.begin();
 }
@@ -44,7 +50,7 @@ void loop() {
 
   // Check if any reads failed and exit early (to try again).
   if (isnan(h) || isnan(t) || isnan(f)) {
-    Serial.println("Failed to read from DHT sensor!");
+    Serial.println(F("Failed to read from DHT sensor!"));
     return;
   }
 
@@ -53,17 +59,15 @@ void loop() {
   // Compute heat index in Celsius (isFahreheit = false)
   float hic = dht.computeHeatIndex(t, h, false);
 
-  Serial.print("Humidity: ");
+  Serial.print(F("Humidity: "));
   Serial.print(h);
-  Serial.print(" %\t");
-  Serial.print("Temperature: ");
+  Serial.print(F("%  Temperature: "));
   Serial.print(t);
-  Serial.print(" *C ");
+  Serial.print(F("°C "));
   Serial.print(f);
-  Serial.print(" *F\t");
-  Serial.print("Heat index: ");
+  Serial.print(F("°F  Heat index: "));
   Serial.print(hic);
-  Serial.print(" *C ");
+  Serial.print(F("°C "));
   Serial.print(hif);
-  Serial.println(" *F");
+  Serial.println(F("°F"));
 }

keywords.txt

@@ -12,11 +12,11 @@ DHT	KEYWORD1
 # Methods and Functions (KEYWORD2)
 ###########################################
 
-begin KEYWORD2
-readTemperature KEYWORD2
-convertCtoF KEYWORD2
-convertFtoC KEYWORD2
-computeHeatIndex KEYWORD2
-readHumidity KEYWORD2
-read KEYWORD2
+begin	KEYWORD2
+readTemperature	KEYWORD2
+convertCtoF	KEYWORD2
+convertFtoC	KEYWORD2
+computeHeatIndex	KEYWORD2
+readHumidity	KEYWORD2
+read	KEYWORD2
 

library.properties

@@ -1,5 +1,5 @@
 name=DHT sensor library
-version=1.1.1
+version=1.3.6
 author=Adafruit
 maintainer=Adafruit <info@adafruit.com>
 sentence=Arduino library for DHT11, DHT22, etc Temp & Humidity Sensors