Add flags to handle localtime/utc selection and NTPSync

src/ArduinoCellular.cpp

@@ -78,7 +78,7 @@ bool ArduinoCellular::connect(String apn, String username, String password, bool
         return true;       
     }
 
-    if(connectToGPRS(apn.c_str(), username.c_str(), password.c_str())){
+    if(connectToGPRS(apn.c_str(), username.c_str(), password.c_str(), waitForever)){
         auto response = this->sendATCommand("+QIDNSCFG=1,\"8.8.8.8\",\"8.8.4.4\"");
 
         if(response.indexOf("OK") != -1){
@@ -126,17 +126,26 @@ Time ArduinoCellular::getGPSTime(){
     return Time(year, month, day, hour, minute, second);
 }
 
-Time ArduinoCellular::getCellularTime(){
+Time ArduinoCellular::getCellularTime(bool localTime, bool forceNTPSync) {
     int year = 1970;
     int month = 1;
     int day = 1;
     int hour = 0;
     int minute = 0;
     int second = 0;
     float tz;
-    if (modem.NTPServerSync() == 0) {
+
+    if ((needNTPSync || forceNTPSync) && (modem.NTPServerSync() != 0)) {
+        return Time(year, month, day, hour, minute, second);
+    }
+    needNTPSync = false;
+
+    if (localTime) {
       modem.getNetworkTime(&year, &month, &day, &hour, &minute, &second, &tz);
+    } else {
+      modem.getNetworkUTCTime(&year, &month, &day, &hour, &minute, &second, &tz);
     }
+
     return Time(year, month, day, hour, minute, second);
 }
 
@@ -187,11 +196,16 @@ bool ArduinoCellular::isConnectedToOperator(){
     return modem.isNetworkConnected();
 }
 
-bool ArduinoCellular::connectToGPRS(const char * apn, const char * gprsUser, const char * gprsPass){
+bool ArduinoCellular::connectToGPRS(const char * apn, const char * gprsUser, const char * gprsPass, bool waitForever){
     if(this->debugStream != nullptr){
         this->debugStream->println("Connecting to 4G network...");
     }
     while(!modem.gprsConnect(apn, gprsUser, gprsPass)) {
+
+        if(!waitForever) {
+            return false;
+        }
+
         if(this->debugStream != nullptr){
             this->debugStream->print(".");
         }
@@ -243,7 +257,7 @@ bool ArduinoCellular::awaitNetworkRegistration(bool waitForever){
         this->debugStream->println("Waiting for network registration...");
     }
     while (!modem.waitForNetwork(waitForNetworkTimeout)) {
-        
+
         if(!waitForever) {
             return false;
         }

src/ArduinoCellular.h

@@ -163,7 +163,7 @@ class ArduinoCellular {
          * @brief Gets the current time from the network.
          * @return The current time.
          */
-        Time getCellularTime();
+        Time getCellularTime(bool localTime = true, bool forceNTPSync = false);
 
         /**
          * @brief Gets the current time from the GPS module.
@@ -276,8 +276,7 @@ class ArduinoCellular {
         SimStatus getSimStatus();
 
     private:
-        bool connectToGPRS(const char * apn, const char * gprsUser, const char * gprsPass);
-
+        bool connectToGPRS(const char * apn, const char * gprsUser, const char * gprsPass, bool waitForever = true);
 
         /**
          * @brief Waits for network registration. (Blocking call)
@@ -304,6 +303,8 @@ class ArduinoCellular {
         static unsigned long getTime(); /** Callback for getting the current time as an unix timestamp. */
 
         static constexpr unsigned long waitForNetworkTimeout = 20000L; /**< Maximum wait time for network registration (In milliseconds). */
+
+        bool needNTPSync = true; /**< Flag to indicate if NTP synchronization is needed. */
 };
 
 

src/TimeUtils.h

@@ -91,19 +91,35 @@ class Time {
          * @return The time in UNIX timestamp format.
          */
         String getUNIXTimestampString() {
-            // Simple conversion to UNIX timestamp, not accounting for leap years or time zones
-            long timestamp = second + minute*60 + hour*3600 + day*86400 + (month-1)*2629743 + (year-1970)*31556926;
-            return String(timestamp);
+            return String(getUNIXTimestamp());
         }
 
         /**
          * Returns the time in UNIX timestamp format.
          * @return The time in UNIX timestamp format.
          */
         unsigned long getUNIXTimestamp() {
-            // Simple conversion to UNIX timestamp, not accounting for leap years or time zones
-            unsigned long timestamp = second + minute*60 + hour*3600 + day*86400 + (month-1)*2629743 + (year-1970)*31556926;
-            return timestamp;
+            struct tm t =
+            {
+              0 /* tm_sec   */,
+              0 /* tm_min   */,
+              0 /* tm_hour  */,
+              0 /* tm_mday  */,
+              0 /* tm_mon   */,
+              0 /* tm_year  */,
+              0 /* tm_wday  */,
+              0 /* tm_yday  */,
+              0 /* tm_isdst */
+            };
+            t.tm_mon = month - 1;
+            t.tm_mday = day;
+            t.tm_year = year - 1900;
+            t.tm_hour = hour;
+            t.tm_min = minute;
+            t.tm_sec = second;
+            t.tm_isdst = -1;
+
+            return mktime(&t);
         }
 
         /**