add 1sec offset scetch example

rtctimestampbias_1sec.ino

@@ -0,0 +1,43 @@
+// RTC timestamp bias: Arduino with DS1307RTC exmaple
+// https://gitlab.com/simplemicrocontrollers/rtctimestampbias
+#include <Thread.h>
+#include <DS1307RTC.h>
+
+// Time bias correction variables:
+long correctionCheck = 43200000;       // Offset in one second per the number of milliseconds
+int correctionBias = 1;
+Thread correctionThread = Thread();    // Time bias correction thread
+
+void setup() {
+  Serial.begin(9600);                  // Initializes the Serial connection @ 9600 baud for debug
+  while (!Serial);                     // Wait until Arduino Serial Monitor opens
+  setSyncProvider(RTC.get);            // The function to get the time from the RTC
+  if(timeStatus()!= timeSet) {         // Checking the time setting
+    Serial.println("Unable to sync with the RTC");
+  } else {
+//    Serial.println("RTC has set the system time");
+    Serial.println(now());             // Sending a timestamp to the serial port if a RTC is detected
+  }
+
+  // Time bias correction thread initialization:
+  correctionThread.onRun(correctionLoop);
+  correctionThread.setInterval(correctionCheck);
+}
+
+void loop() {
+  // Threads:
+  if (correctionThread.shouldRun())
+    correctionThread.run();
+}
+
+void correctionLoop() {
+  tmElements_t RTCtime;
+  RTC.read(RTCtime);
+  time_t RTCtimestamp;
+  RTCtimestamp = makeTime(RTCtime);
+  tmElements_t timeNew;
+  time_t newTimestamp = RTCtimestamp - correctionBias;
+  breakTime(newTimestamp, timeNew);
+  RTC.write(timeNew);
+  setSyncProvider(RTC.get);
+}