From e375a0b11f72e45f2a43f353c14c40e508885db7 Mon Sep 17 00:00:00 2001
From: edwin <edwinman7@yahoo.com>
Date: Tue, 6 Dec 2022 15:00:19 +0800
Subject: [PATCH] define an empty constructor and overload DHT::begin

---
 DHT.cpp | 40 ++++++++++++++++++++++++++++++++++++++++
 DHT.h   |  2 ++
 2 files changed, 42 insertions(+)

diff --git a/DHT.cpp b/DHT.cpp
index a48ac74..f8fa3d4 100644
--- a/DHT.cpp
+++ b/DHT.cpp
@@ -30,6 +30,24 @@
   UINT32_MAX /**< Used programmatically for timeout.                           \
                    Not a timeout duration. Type: uint32_t. */
 
+/**
+ * @brief Instantiates a default DHT class
+ * 
+ */
+DHT::DHT() {
+  _pin = 2;  // pin 2 set as the default data pin 
+  _type = DHT11; // using the DHT11 sensor as the default sensor type.
+  // Note that pin 2 and DHT11 are just default values to
+  // initialize members _pin and _type in the class definition.
+  // They can be modified via DHT::begin(uint8_t pin, uint8_t type, uint8_t usec).
+#ifdef __AVR
+  _bit = digitalPinToBitMask(pin);
+  _port = digitalPinToPort(pin);
+#endif
+  _maxcycles = microsecondsToClockCycles(1000); // 1 millisecond timeout for
+                                                // reading pulses from DHT sensor.
+}
+
 /*!
  *  @brief  Instantiates a new DHT class
  *  @param  pin
@@ -72,6 +90,28 @@ void DHT::begin(uint8_t usec) {
   pullTime = usec;
 }
 
+/**
+ * @brief Setup sensor pins and set pull timings
+ * 
+ * @param pin 
+ *        pin number that sensor is connected
+ * @param type 
+ *        type of sensor
+ * @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 pin, uint8_t type, uint8_t usec)
+{
+  _pin = pin;
+  _type = type;
+#ifdef __AVR
+  _bit = digitalPinToBitMask(pin);
+  _port = digitalPinToPort(pin);
+#endif
+  begin(usec);
+}
+
 /*!
  *  @brief  Read temperature
  *  @param  S
diff --git a/DHT.h b/DHT.h
index 95570e1..5e3db94 100644
--- a/DHT.h
+++ b/DHT.h
@@ -62,8 +62,10 @@ static const uint8_t AM2301{21}; /**< AM2301 */
  */
 class DHT {
 public:
+  DHT();
   DHT(uint8_t pin, uint8_t type, uint8_t count = 6);
   void begin(uint8_t usec = 55);
+  void begin(uint8_t pin, uint8_t type, uint8_t usec = 55);
   float readTemperature(bool S = false, bool force = false);
   float convertCtoF(float);
   float convertFtoC(float);