Update example to properly use millisecond

Signed-off-by: Frederic Pillon <frederic.pillon@st.com>

Author: fpistm

examples/AlarmTimedWakeup/AlarmTimedWakeup.ino

@@ -17,8 +17,9 @@
 /* Get the rtc object */
 STM32RTC& rtc = STM32RTC::getInstance();
 
-// Time in second between blink
-static uint32_t atime = 1;
+/* Change this value to set alarm match offset in millisecond */
+/* Note that STM32F1xx does not manage subsecond only second */
+static uint32_t atime = 567;
 
 // Declare it volatile since it's incremented inside an interrupt
 volatile int alarmMatch_counter = 0;
@@ -41,21 +42,21 @@ void setup() {
   pinMode(LED_BUILTIN, OUTPUT);
 
   Serial.begin(9600);
-  while(!Serial) {}
+  while (!Serial) {}
 
   // Configure low power
   LowPower.begin();
   LowPower.enableWakeupFrom(&rtc, alarmMatch, &atime);
 
   // Configure first alarm in 2 second then it will be done in the rtc callback
-  rtc.setAlarmEpoch( rtc.getEpoch() + 2 );
+  rtc.setAlarmEpoch( rtc.getEpoch() + 2, rtc.MATCH_DHHMMSS, atime );
 }
 
 void loop() {
   Serial.print("Alarm Match: ");
   Serial.print(alarmMatch_counter);
   Serial.println(" times.");
-  delay(100);
+  Serial.flush();
   digitalWrite(LED_BUILTIN, HIGH);
   LowPower.deepSleep();
   digitalWrite(LED_BUILTIN, LOW);
@@ -67,15 +68,37 @@ void alarmMatch(void* data)
   // This function will be called once on device wakeup
   // You can do some little operations here (like changing variables which will be used in the loop)
   // Remember to avoid calling delay() and long running functions since this functions executes in interrupt context
-  uint32_t sec = 1;
-  if(data != NULL) {
-    sec = *(uint32_t*)data;
+  uint32_t epoc;
+  uint32_t epoc_ms;
+  uint32_t sec = 0;
+  uint32_t _millis = 1000;
+
+  if (data != NULL) {
+    _millis = *(uint32_t*)data;
     // Minimum is 1 second
-    if (sec == 0){
+    if (sec == 0) {
       sec = 1;
     }
   }
+
+  sec = _millis / 1000;
+#ifdef STM32F1xx
+  // Minimum is 1 second
+  if (sec == 0) {
+    sec = 1;
+  }
+  epoc = rtc.getEpoch(&epoc_ms);
+#else
+  _millis = _millis % 1000;
+  epoc = rtc.getEpoch(&epoc_ms);
+
+  //Update epoch_ms - might need to add a second to epoch
+  epoc_ms += _millis;
+  if (epoc_ms >= 1000) {
+    sec ++;
+    epoc_ms -= 1000;
+  }
+#endif
   alarmMatch_counter++;
-  rtc.setAlarmEpoch( rtc.getEpoch() + sec);
+  rtc.setAlarmEpoch(epoc + sec, STM32RTC::MATCH_SS, epoc_ms);
 }
-