[SYS] Add utc & unix timestamp options to SYStoMQTT and Sensor messages (#1533)

Add optional timestamps to the SYStoMQTT and modules messages
Also, the sync with the NTP time server now occurs every hour (can be defined with TimeBetweenCheckingSYS in UserConfig.h)

main/User_config.h

@@ -386,6 +386,12 @@ int lowpowermode = DEFAULT_LOW_POWER_MODE;
 #ifndef simpleReceiving
 #  define simpleReceiving true //define false if you don't want to use old way reception analysis
 #endif
+#ifndef message_UTCtimestamp
+#  define message_UTCtimestamp false //define true if you want messages to be timestamped in ISO8601 UTC format (e.g.: "UTCtime"="2023-12-26T19:10:20Z")
+#endif
+#ifndef message_unixtimestamp
+#  define message_unixtimestamp false //define true if you want messages to have an unix timestamp (e.g.: "unixtime"=1679015107)
+#endif
 
 /*-------------DEFINE YOUR OTA PARAMETERS BELOW----------------*/
 #ifndef ota_hostname

main/ZgatewayBT.ino

@@ -592,6 +592,14 @@ void procBLETask(void* pvParameters) {
       String mac_adress = advertisedDevice->getAddress().toString().c_str();
       mac_adress.toUpperCase();
       BLEdata["id"] = (char*)mac_adress.c_str();
+#  if defined(ESP8266) || defined(ESP32)
+#    if message_UTCtimestamp == true
+      BLEdata["UTCtime"] = UTCtimestamp();
+#    endif
+#    if message_unixtimestamp == true
+      BLEdata["unixtime"] = unixtimestamp();
+#    endif
+#  endif
       BLEdata["mac_type"] = advertisedDevice->getAddress().getType();
       BLEdata["adv_type"] = advertisedDevice->getAdvType();
       Log.notice(F("Device detected: %s" CR), (char*)mac_adress.c_str());

main/main.ino

@@ -1613,6 +1613,9 @@ void loop() {
       if (now > (timer_sys_checks + (TimeBetweenCheckingSYS * 1000)) || !timer_sys_checks) {
 #  if defined(ESP32) && defined(MQTT_HTTPS_FW_UPDATE)
         checkForUpdates();
+#  endif
+#  if defined(ESP8266) || defined(ESP32)
+        syncNTP();
 #  endif
         timer_sys_checks = millis();
       }
@@ -1782,11 +1785,54 @@ float intTemperatureRead() {
 }
 #endif
 
+#if defined(ESP8266) || defined(ESP32)
+void syncNTP() {
+  configTime(0, 0, NTP_SERVER);
+  time_t now = time(nullptr);
+  uint8_t count = 0;
+  Log.trace(F("Waiting for NTP time sync" CR));
+  while ((now < 8 * 3600 * 2) && count++ < 60) {
+    delay(500);
+    now = time(nullptr);
+  }
+
+  if (count >= 60) {
+    Log.error(F("Unable to update - invalid time" CR));
+#  if defined(ZgatewayBT) && defined(ESP32)
+    startProcessing();
+#  endif
+    return;
+  }
+}
+
+int unixtimestamp() {
+  return time(nullptr);
+}
+
+String UTCtimestamp() {
+  time_t now;
+  time(&now);
+  char buffer[sizeof "yyyy-MM-ddThh:mm:ssZ"];
+  strftime(buffer, sizeof buffer, "%FT%TZ", gmtime(&now));
+  return buffer;
+}
+
+#endif
+
 #if defined(ESP8266) || defined(ESP32) || defined(__AVR_ATmega2560__) || defined(__AVR_ATmega1280__)
 void stateMeasures() {
   StaticJsonDocument<JSON_MSG_BUFFER> jsonBuffer;
   JsonObject SYSdata = jsonBuffer.to<JsonObject>();
   SYSdata["uptime"] = uptime();
+#  if defined(ESP8266) || defined(ESP32)
+#    if message_UTCtimestamp == true
+  SYSdata["UTCtime"] = UTCtimestamp();
+#    endif
+#    if message_unixtimestamp == true
+  SYSdata["unixtime"] = unixtimestamp();
+#    endif
+#  endif
+
   SYSdata["version"] = OMG_VERSION;
 #  ifdef ZmqttDiscovery
   SYSdata["discovery"] = disc;
@@ -2175,22 +2221,7 @@ void MQTTHttpsFWUpdate(char* topicOri, JsonObject& HttpsFwUpdateData) {
           client.disconnect();
           update_client = *(WiFiClientSecure*)eClient;
         } else {
-          configTime(0, 0, NTP_SERVER);
-          time_t now = time(nullptr);
-          uint8_t count = 0;
-          Log.trace(F("Waiting for NTP time sync" CR));
-          while ((now < 8 * 3600 * 2) && count++ < 60) {
-            delay(500);
-            now = time(nullptr);
-          }
-
-          if (count >= 60) {
-            Log.error(F("Unable to update - invalid time" CR));
-#  if defined(ZgatewayBT) && defined(ESP32)
-            startProcessing();
-#  endif
-            return;
-          }
+          syncNTP();
         }
 
 #  ifdef ESP32