add reset() + add lastRead() (#49)

* add reset()
* add lastRead()

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2017-2020 Rob Tillaart
+Copyright (c) 2017-2021 Rob Tillaart
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -74,6 +74,9 @@ Added Arduino-CI support + **gettype()** now tries to determine type if not know
 18. (0.4.2)
 Fix negative temperatures. Tested with DHTNew_debug.ino and hexdump in .cpp and a freezer.  
 Note: testing in a freezer is not so good for humidity readings.
+19. (0.4.3)
+Added **reset()** to reset internal variables when a sensor blocks this might help.
+Added **lastRead()** to return time the sensor is last read. (in millis).
 
 
 ## DHT PIN layout from left to right
@@ -88,36 +91,36 @@ Note: testing in a freezer is not so good for humidity readings.
 
 ## Specification DHT22
 
-| | | |
+| Model                     | DHT22         | Notes |
 |:----|:----|:----|
-| Model | DHT22 |
-| Power supply | 3.3 - 6 V DC | 
-| Output signal | digital signal via single-bus | 
-| Sensing element | Polymer capacitor | 
-| Operating range | humidity 0-100% RH | temperature -40~80° Celsius | 
-| Accuracy humidity | ±2% RH(Max ±5% RH) | temperature < ±0.5° Celsius | 
-| Resolution or sensitivity | humidity 0.1% RH | temperature 0.1° Celsius | 
-| Repeatability humidity | ±1% RH | temperature ±0.2° Celsius | 
-| Humidity hysteresis | ±0.3% RH | 
-| Long-term Stability | ±0.5% RH/year | 
-| Sensing period | Average: 2s | 
-| Interchangeability |  fully interchangeable | 
-| Dimensions | small size 14 x 18 x 5.5 mm;  | big size 22 x 28 x 5 mm | 
+| Power supply              | 3.3 - 6 V DC  | 
+| Output signal             | digital signal via single-bus | 
+| Sensing element           | Polymer capacitor  | 
+| Operating range           | humidity 0-100% RH | temperature -40~80° Celsius | 
+| Accuracy humidity         | ±2% RH(Max ±5% RH) | temperature < ±0.5° Celsius | 
+| Resolution or sensitivity | humidity 0.1% RH   | temperature 0.1° Celsius | 
+| Repeatability humidity    | ±1% RH             | temperature ±0.2° Celsius | 
+| Humidity hysteresis       | ±0.3% RH           | 
+| Long-term Stability       | ±0.5% RH/year      | 
+| Sensing period            | Average: 2s        | 
+| Interchangeability        | fully interchangeable  | 
+| Dimensions                | small 14 x 18 x 5.5 mm | big 22 x 28 x 5 mm | 
 
 
 ## Interface
 
-To elaborated
-
 
 ### Constructor
+
 - **DHTNEW(uint8_t pin)** defines the datapin of the sensor.
+- **reset()** might help to reset a sensor behaving badly.
 - **getType()**  0 = unknown, 11 or 22. 
 In case of 0, **getType()** will try to determine type.
 - **setType(uint8_t type = 0)** allows to force the type of the sensor. 
 
 
 ### Base interface
+
 - **read()** reads a new temperature and humidity from the sensor
 - **lastRead()** returns milliseconds since last **read()**
 - **getHumidity()** returns last read value (float) or -999 in case of error. 
@@ -126,15 +129,19 @@ Note this error value can be suppressed by **setSuppressError(bool)**.
 
 
 ### Offset 
+
 Adding offsets works well in normal range however they might introduce under- or overflow at the ends of the sensor range.
+
 - **setHumOffset(float offset)** typical < ±5% RH.
 - **setTempOffset(float offset)** typical < ±2°C.
 - **getHumOffset()** idem.
 - **getTempOffset()** idem.
 
 
 ### Control
+
 Functions to adjust the communication with the sensor.
+
 - **setDisableIRQ(bool b )** allows or suppresses interrupts during core read function to keep timing as correct as possible. **Note AVR only**
 - **getDisableIRQ()** returns the above setting. Default **false**
 - **setWaitForReading(bool b )** flag to enforce a blocking wait. 

dhtnew.cpp

@@ -1,48 +1,52 @@
 //
 //    FILE: dhtnew.cpp
 //  AUTHOR: Rob.Tillaart@gmail.com
-// VERSION: 0.4.2
+// VERSION: 0.4.3
 // PURPOSE: DHT Temperature & Humidity Sensor library for Arduino
 //     URL: https://github.com/RobTillaart/DHTNEW
 //
-// HISTORY:
-// 0.1.0  2017-07-24 initial version based upon DHTStable
-// 0.1.1  2017-07-29 add begin() to determine type once and for all instead of every call + refactor
-// 0.1.2  2018-01-08 improved begin() + refactor()
-// 0.1.3  2018-01-08 removed begin() + moved detection to read() function
-// 0.1.4  2018-04-03 add get-/setDisableIRQ(bool b)
-// 0.1.5  2019-01-20 fix negative temperature DHT22 - issue #120
-// 0.1.6  2020-04-09 #pragma once, readme.md, own repo
-// 0.1.7  2020-05-01 prevent premature read; add waitForReading flag (Kudo's to Mr-HaleYa),
-// 0.2.0  2020-05-02 made temperature and humidity private (Kudo's to Mr-HaleYa),
-// 0.2.1  2020-05-27 Fix #11 - Adjust bit timing threshold
-// 0.2.2  2020-06-08 added ERROR_SENSOR_NOT_READY and differentiate timeout errors
-// 0.3.0  2020-06-12 added getReadDelay & setReadDelay to tune reading interval
-//                   removed get/setDisableIRQ; adjusted wakeup timing; refactor
-// 0.3.1  2020-07-08 added powerUp() powerDown();
-// 0.3.2  2020-07-17 fix #23 added get/setSuppressError(); overrulable DHTLIB_INVALID_VALUE
-// 0.3.3  2020-08-18 fix #29, create explicit delay between pulling line HIGH and 
-//                   waiting for LOW in handshake to trigger the sensor.
-//                   On fast ESP32 this fails because the capacity / voltage of the long wire
-//                   cannot rise fast enough to be read back as HIGH.
-// 0.3.4  2020-09-23 Added **waitFor(state, timeout)** to follow timing from datasheet.
-//                   Restored disableIRQ flag as problems occured on AVR. The default of 
-//                   this flag on AVR is false so interrupts are allowed. 
-//                   This need some investigation
-//                   Fix wake up timing for DHT11 as it does not behave according datasheet.
-//                   fix wakeupDelay bug in setType();
-// 0.4.0  2020-11-10 added DHTLIB_WAITING_FOR_READ as return value of read (minor break of interface)
-// 0.4.1  2020-11-11 getType() attempts to detect sensor type
-//        2020-12-12 add arduino -CI + readme
-// 0.4.2  2020-12-15 fix negative temperatures
+//  HISTORY:
+//  0.1.0  2017-07-24  initial version based upon DHTStable
+//  0.1.1  2017-07-29  add begin() to determine type once and for all instead of every call + refactor
+//  0.1.2  2018-01-08  improved begin() + refactor()
+//  0.1.3  2018-01-08  removed begin() + moved detection to read() function
+//  0.1.4  2018-04-03  add get-/setDisableIRQ(bool b)
+//  0.1.5  2019-01-20  fix negative temperature DHT22 - issue #120
+//  0.1.6  2020-04-09  #pragma once, readme.md, own repo
+//  0.1.7  2020-05-01  prevent premature read; add waitForReading flag (Kudo's to Mr-HaleYa),
+//  0.2.0  2020-05-02  made temperature and humidity private (Kudo's to Mr-HaleYa),
+//  0.2.1  2020-05-27  Fix #11 - Adjust bit timing threshold
+//  0.2.2  2020-06-08  added ERROR_SENSOR_NOT_READY and differentiate timeout errors
+//  0.3.0  2020-06-12  added getReadDelay & setReadDelay to tune reading interval
+//                     removed get/setDisableIRQ; adjusted wakeup timing; refactor
+//  0.3.1  2020-07-08  added powerUp() powerDown();
+//  0.3.2  2020-07-17  fix #23 added get/setSuppressError(); overrulable DHTLIB_INVALID_VALUE
+//  0.3.3  2020-08-18  fix #29, create explicit delay between pulling line HIGH and 
+//                     waiting for LOW in handshake to trigger the sensor.
+//                     On fast ESP32 this fails because the capacity / voltage of the long wire
+//                     cannot rise fast enough to be read back as HIGH.
+//  0.3.4  2020-09-23  Added **waitFor(state, timeout)** to follow timing from datasheet.
+//                     Restored disableIRQ flag as problems occured on AVR. The default of 
+//                     this flag on AVR is false so interrupts are allowed. 
+//                     This need some investigation
+//                     Fix wake up timing for DHT11 as it does not behave according datasheet.
+//                     fix wakeupDelay bug in setType();
+//  0.4.0  2020-11-10  added DHTLIB_WAITING_FOR_READ as return value of read (minor break of interface)
+//  0.4.1  2020-11-11  getType() attempts to detect sensor type
+//         2020-12-12  add arduino -CI + readme
+//  0.4.2  2020-12-15  fix negative temperatures
+//  0.4.3  2021-01-13  add reset(), add lastRead()
 
 
 #include "dhtnew.h"
 #include <stdint.h>
+
+
 // these defines are not for user to adjust
 #define DHTLIB_DHT11_WAKEUP        18
 #define DHTLIB_DHT_WAKEUP          1
 
+
 // READ_DELAY for blocking read
 // datasheet: DHT11 = 1000 and DHT22 = 2000
 // use setReadDelay() to overrule (at own risk)
@@ -51,28 +55,48 @@
 #define DHTLIB_DHT11_READ_DELAY    1000
 #define DHTLIB_DHT22_READ_DELAY    2000
 
+
 /////////////////////////////////////////////////////
 //
 // PUBLIC
 //
 DHTNEW::DHTNEW(uint8_t pin)
 {
   _dataPin = pin;
+  reset();
+};
+
+
+void DHTNEW::reset()
+{
   // Data-bus's free status is high voltage level.
   pinMode(_dataPin, OUTPUT);
   digitalWrite(_dataPin, HIGH);
-  _readDelay = 0;
-  #if defined(__AVR__)
+
+  _wakeupDelay   = 0;
+  _type          = 0;
+  _humOffset     = 0.0;
+  _tempOffset    = 0.0;
+  _humidity      = 0.0;
+  _temperature   = 0.0;
+  _lastRead      = 0;
+  _disableIRQ    = true;
+  _waitForRead   = false;
+  _suppressError = false;
+  _readDelay     = 0;
+#if defined(__AVR__)
   _disableIRQ = false;
-  #endif
-};
+#endif
+}
+
 
 uint8_t DHTNEW::getType()
 {
   if (_type == 0) read();
   return _type;
 }
 
+
 void DHTNEW::setType(uint8_t type)
 {
   if ((type == 0) || (type == 11))
@@ -87,6 +111,7 @@ void DHTNEW::setType(uint8_t type)
   }
 }
 
+
 // return values:
 // DHTLIB_OK
 // DHTLIB_WAITING_FOR_READ
@@ -128,6 +153,7 @@ int DHTNEW::read()
   return rv;
 }
 
+
 // return values:
 // DHTLIB_OK
 // DHTLIB_ERROR_CHECKSUM
@@ -209,18 +235,21 @@ int DHTNEW::_read()
   return DHTLIB_OK;
 }
 
+
 void DHTNEW::powerUp()
 {
   digitalWrite(_dataPin, HIGH);
   // do a dummy read to sync the sensor
   read();
 };
 
+
 void DHTNEW::powerDown()
 {
   digitalWrite(_dataPin, LOW);
 }
 
+
 /////////////////////////////////////////////////////
 //
 // PRIVATE

dhtnew.h

@@ -2,13 +2,14 @@
 //
 //    FILE: dhtnew.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.4.2
+// VERSION: 0.4.3
 // PURPOSE: DHT Temperature & Humidity Sensor library for Arduino
 //     URL: https://github.com/RobTillaart/DHTNEW
 //
 // HISTORY:
 // see dhtnew.cpp file
 
+
 // DHT PIN layout from left to right
 // =================================
 // FRONT : DESCRIPTION
@@ -17,9 +18,11 @@
 // pin 3 : Not Connected
 // pin 4 : GND
 
+
 #include "Arduino.h"
 
-#define DHTNEW_LIB_VERSION          "0.4.2"
+#define DHTNEW_LIB_VERSION                (F("0.4.2"))
+
 
 #define DHTLIB_OK                         0
 #define DHTLIB_ERROR_CHECKSUM            -1
@@ -51,6 +54,10 @@ class DHTNEW
 
   DHTNEW(uint8_t pin);
 
+  // resets all internals to construction time 
+  // might help to reset a sensor behaving badly..
+  void     reset();
+
   // 0 = unknown, 11 or 22
   uint8_t  getType();
   void     setType(uint8_t type = 0);
@@ -89,6 +96,7 @@ class DHTNEW
   bool     getSuppressError()            { return _suppressError; };
   void     setSuppressError(bool b)      { _suppressError = b; };
 
+
 private:
   uint8_t  _dataPin       = 0;
   uint8_t  _wakeupDelay   = 0;

keywords.txt

@@ -4,6 +4,7 @@
 DHTNEW	KEYWORD1
 
 # Methods and Functions (KEYWORD2)
+reset	KEYWORD2
 getType	KEYWORD2
 setType()	KEYWORD2
 read	KEYWORD2
@@ -17,6 +18,9 @@ setTempOffset	KEYWORD2
 getHumOffset	KEYWORD2
 getTempOffset	KEYWORD2
 
+getDisableIRQ	KEYWORD2
+setDisableIRQ	KEYWORD2
+
 getWaitForReading	KEYWORD2
 setWaitForReading	KEYWORD2
 getSuppressError	KEYWORD2
@@ -43,3 +47,5 @@ DHTLIB_ERROR_TIMEOUT_C	LITERAL1
 DHTLIB_ERROR_TIMEOUT_D	LITERAL1
 DHTLIB_ERROR_SENSOR_NOT_READY	LITERAL1
 DHTLIB_WAITING_FOR_READ	LITERAL1
+DHTLIB_BIT_THRESHOLD	LITERAL1
+

library.json

@@ -13,7 +13,7 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/DHTNEW.git"
   },
-  "version":"0.4.2",
+  "version":"0.4.3",
   "frameworks": "arduino",
   "platforms": "*"
 }

library.properties

@@ -1,5 +1,5 @@
 name=DHTNEW
-version=0.4.2
+version=0.4.3
 author=Rob Tillaart <rob.tillaart@gmail.com>
 maintainer=Rob Tillaart <rob.tillaart@gmail.com>
 sentence=Arduino library for DHT temperature and humidity sensor, with automatic sensortype recognition.