v1.8.1 to add waitingForDRD() function

### Releases v1.8.1

1. Add waitingForDRD() function to signal in DRD wating period. Check [DRD is waiting for a double reset? #14](khoih-prog/ESP_DoubleResetDetector#14)
2. Add example [checkWaitingDRD](https://github.com/khoih-prog/DoubleResetDetector_Generic/tree/master/examples/checkWaitingDRD) to demo how to use the new feature.
3. Add support to `Sparkfun Pro nRF52840 Mini`
4. Update `Packages' Patches`

examples/checkWaitingDRD/checkWaitingDRD.ino

@@ -0,0 +1,164 @@
+/****************************************************************************************************************************
+   checkWaitingDRD.ino
+   DoubleResetDetector_Generic.h
+  For AVR Mega, Teensy, STM32, nRF52, SAM DUE, SAMD21, SAMD51 boards
+
+  DoubleResetDetector_Generic is a library for the Arduino AVR, Teensy, SAM-DUE, SAMD, STM32. etc. boards
+  to enable trigger configure mode by resetting the boards twice within configurable timeout seconds.
+
+  Based on and modified from DataCute https://github.com/datacute/DoubleResetDetector and
+  https://github.com/khoih-prog/ESP_DoubleResetDetector
+
+  Built by Khoi Hoang https://github.com/khoih-prog/DoubleResetDetector_Generic
+  Licensed under MIT license
+ *****************************************************************************************************************************/
+
+/****************************************************************************************************************************
+   This example will open a configuration portal when the reset button is pressed twice.
+   This method works well on Wemos boards which have a single reset button on board. It avoids using a pin for launching the configuration portal.
+
+   How It Works
+   1) AVR Mega, Teensy
+   Save data in EPPROM from address 1020, size 1024 bytes (both configurable)
+   Note: Teensy 4.0 has only 1080 bytes of EEPROM-simulated Flash
+   2) SAMD
+   Save data in EEPROM-simulated FlashStorage from address 0 (configurable to avoid conflict)
+   3) SAM DUE
+   Save data in DueFlashStorage from address 1020 (configurable to avoid conflict)
+   4) Adafruit nRF52-based boards
+   Save data in InternalFS, fle "/drd.dat" location 0
+   5) RTL8720
+   Save data in FlashStorage from address 0 (configurable to avoid conflict)
+   6) STM32
+   Save data in EEPROM-simulated FlashStorage from address 0 (configurable to avoid conflict)
+
+   So when the device starts up it checks the InternalFS file "/drd.dat", EEPROM or (Due)FlashStorage for a flag to see if it has been
+   recently reset within the configurable timeout seconds
+   It'll then set a flag, and display a message to signal if the DR is detected
+
+   Settings
+   There are two values to be set in the sketch.
+
+   DRD_TIMEOUT - Number of seconds to wait for the second reset. Set to 10s in the example.
+   DRD_ADDRESS - The address in ESP8266 RTC RAM to store the flag. This memory must not be used for other purposes in the same sketch. Set to 0 in the example.
+
+   This example, originally relied on the Double Reset Detector library from https://github.com/datacute/DoubleResetDetector
+   To support ESP32, use ESP_DoubleResetDetector library from https://github.com/khoih-prog/ESP_DoubleResetDetector
+   To support AVR, Teensy, SAM DUE, SAMD and STM32, etc., use this DoubleResetDetector_Generic from //https://github.com/khoih-prog/DoubleResetDetector_Generic
+ *****************************************************************************************************************************/
+
+
+// These defines must be put before #include <DoubleResetDetector_Generic.h>
+// to select where to store DoubleResetDetector's variable.
+// For ESP32, You must select one to be true (EEPROM or SPIFFS)
+// For ESP8266, You must select one to be true (RTC, EEPROM, LITTLEFS or SPIFFS)
+// Otherwise, library will use default EEPROM storage
+
+// This example demonstrates how to use new function waitingForDRD() to signal the stage of DRD
+// waitingForDRD() returns true if in DRD_TIMEOUT, false when out of DRD_TIMEOUT
+// In this example, LED_BUILTIN will blink in DRD_TIMEOUT period, ON when DR has been detected, OFF otherwise
+
+#define DRD_GENERIC_DEBUG       false
+
+// You have to select true for the first time for any board
+#define FORCE_REFORMAT          false
+
+// Uncomment to have debug
+//#define DOUBLERESETDETECTOR_DEBUG       true
+
+#include <DoubleResetDetector_Generic.h>      //https://github.com/khoih-prog/DoubleResetDetector_Generic
+
+// Number of seconds after reset during which a 
+// subsequent reset will be considered a double reset.
+#define DRD_TIMEOUT 10
+
+// RTC Memory Address for the DoubleResetDetector to use
+#define DRD_ADDRESS 0
+
+DoubleResetDetector_Generic* drd;
+
+// Change according to your board
+#ifndef LED_BUILTIN
+  // Generic boards following LED at pin 13
+  #define LED_BUILTIN       13
+#endif
+
+// Change according to your board
+#define LED_OFF             LOW
+#define LED_ON              HIGH
+
+bool DRD_Detected = false;
+
+void check_status()
+{
+  static unsigned long checkstatus_timeout  = 0;
+  static bool LEDState = LED_OFF;
+
+  static unsigned long current_millis;
+
+#define DRD_CHECK_INTERVAL    500L
+
+  current_millis = millis();
+
+  // If DRD_Detected, don't need to blink, just keep LED_BUILTIN ON
+  if ( !DRD_Detected && ((current_millis > checkstatus_timeout) || (checkstatus_timeout == 0)) )
+  {
+    // If in DRD checking loop, blinking the LED_BUILTIN
+    if ( drd->waitingForDRD() )
+    {
+      digitalWrite(LED_BUILTIN, LEDState);
+
+      LEDState = !LEDState;    
+    }
+    else
+    {
+      digitalWrite(LED_BUILTIN, LED_OFF);
+    }
+
+    checkstatus_timeout = current_millis + DRD_CHECK_INTERVAL;
+  }
+}
+
+void setup()
+{
+  pinMode(LED_BUILTIN, OUTPUT);
+
+  Serial.begin(115200);
+  while (!Serial);
+
+  delay(200);
+
+#if defined(BOARD_NAME)
+  Serial.print(F("\nStarting checkWaitingDRD on")); Serial.println(BOARD_NAME);
+#else
+  Serial.print(F("\nStarting checkWaitingDRD"));
+#endif  
+
+  Serial.println(DOUBLERESETDETECTOR_GENERIC_VERSION);
+  Serial.println("-----------------------------------");
+
+  drd = new DoubleResetDetector_Generic(DRD_TIMEOUT, DRD_ADDRESS);
+
+  if (drd->detectDoubleReset()) 
+  {
+    Serial.println("Double Reset Detected");
+    digitalWrite(LED_BUILTIN, LED_ON);
+    DRD_Detected = true;
+  } 
+  else 
+  {
+    Serial.println("No Double Reset Detected");
+    digitalWrite(LED_BUILTIN, LED_OFF);
+  }
+}
+
+void loop()
+{
+  // Call the double reset detector loop method every so often,
+  // so that it can recognise when the timeout expires.
+  // You can also call drd.stop() when you wish to no longer
+  // consider the next reset as a double reset.
+  drd->loop();
+
+  check_status();
+}

examples/minimal/minimal.ino

@@ -46,7 +46,7 @@
    To support AVR, Teensy, SAM DUE, SAMD and STM32, etc., use this DoubleResetDetector_Generic from //https://github.com/khoih-prog/DoubleResetDetector_Generic
  *****************************************************************************************************************************/
 
-#define DRD_GENERIC_DEBUG       true  //false
+#define DRD_GENERIC_DEBUG       false
 
 // You have to select true for the first time for any board
 #define FORCE_REFORMAT          false
@@ -64,7 +64,7 @@
 DoubleResetDetector_Generic* drd;
 
 #ifndef LED_BUILTIN
-#define LED_BUILTIN       25  //13
+  #define LED_BUILTIN       25  //13
 #endif
 
 void setup()