added method to test if time was set correctly

NTPClient.cpp

@@ -101,6 +101,10 @@ bool NTPClient::update() {
   return true;
 }
 
+bool NTPClient::isTimeSet() const {
+  return (this->_lastUpdate != 0); // returns true if the time has been set, else false
+}
+
 unsigned long NTPClient::getEpochTime() const {
   return this->_timeOffset + // User offset
          this->_currentEpoc + // Epoc returned by the NTP server

NTPClient.h

@@ -65,6 +65,13 @@ class NTPClient {
      */
     bool forceUpdate();
 
+    /**
+     * This allows to check if the NTPClient successfully received a NTP packet and set the time.
+     *
+     * @return true if time has been set, else false
+     */
+    bool isTimeSet() const;
+
     int getDay() const;
     int getHours() const;
     int getMinutes() const;

examples/IsTimeSet/IsTimeSet.ino

@@ -0,0 +1,53 @@
+#include <NTPClient.h>
+// change next line to use with another board/shield
+#include <ESP8266WiFi.h>
+//#include <WiFi.h> // for WiFi shield
+//#include <WiFi101.h> // for WiFi 101 shield or MKR1000
+#include <WiFiUdp.h>
+
+const char *ssid     = "<SSID>";
+const char *password = "<PASSWORD>";
+
+WiFiUDP ntpUDP;
+// initialized to a time offset of 10 hours
+NTPClient timeClient(ntpUDP,"pool.ntp.org", 36000,);
+//                           HH:MM:SS
+// timeClient initializes to 10:00:00 if it does not receive an NTP packet
+// before the 100ms timeout.
+// Without isTimeSet() the LED would be switched on, although the time
+// was not yet set correctly.
+
+// blue led on ESP12F
+const int led = 2;
+const int hour = 10;
+const int minute = 0;
+
+void setup(){
+  Serial.begin(115200);
+
+  pinMode(led, OUTPUT);
+  // led is off when pin is high
+  digitalWrite(led, 1);
+
+  WiFi.begin(ssid, password);
+
+  while ( WiFi.status() != WL_CONNECTED ) {
+    delay ( 500 );
+    Serial.print ( "." );
+  }
+
+  timeClient.begin();
+}
+
+void loop() {
+  timeClient.update();
+
+  Serial.println(timeClient.getFormattedTime());
+  if(timeClient.isTimeSet()) {
+    if (hour == timeClient.getHours() && minute == timeClient.getMinutes()) {
+      digitalWrite(led, 0);
+    }
+  }
+
+  delay(1000);
+}

keywords.txt

@@ -12,6 +12,7 @@ begin	KEYWORD2
 end	KEYWORD2
 update	KEYWORD2
 forceUpdate	KEYWORD2
+isTimeSet KEYWORD2
 getDay	KEYWORD2
 getHours	KEYWORD2
 getMinutes	KEYWORD2