add new sketch to change the rtc mode

examples/changeMode/changeMode.ino

@@ -0,0 +1,82 @@
+/*
+  change RTC mode from BCD --> MIX --> BIN
+
+  This sketch shows that changing the RTC mode does not affect the calendar
+  Configure the RTC, set an alarm, on alarm match change the RTC mode.
+
+  Creation 01 march 2024
+  by Francois Ramu for STMicroelectronics
+
+  This example code is in the public domain.
+
+  https://github.com/stm32duino/STM32RTC
+*/
+
+#include <STM32RTC.h>
+
+/* Get the rtc object */
+STM32RTC& rtc = STM32RTC::getInstance();
+bool rtc_mode_changed;
+
+void setup()
+{
+  Serial.begin(115200);
+
+  // Select RTC clock source: LSI_CLOCK, LSE_CLOCK or HSE_CLOCK.
+  rtc.setClockSource(STM32RTC::LSE_CLOCK);
+
+  /* Configure the RTC mode */
+  rtc.setBinaryMode(STM32RTC::MODE_BCD);
+  rtc_mode_changed = true;
+
+  /* RTC mode is in BCD mode by default */
+  rtc.begin(true, STM32RTC::HOUR_24);
+
+  /* wait for a while */
+  delay(500);
+
+  // Set the calendar
+  rtc.setDate(01, 03, 24);
+  rtc.setTime(14, 02, 58);
+
+  // Program ALARM A to change the RTC mode (set then enable)
+  rtc.attachInterrupt(alarmMatch);
+  rtc.setAlarmSeconds(5, STM32RTC::ALARM_A);
+  rtc.enableAlarm(rtc.MATCH_SS, STM32RTC::ALARM_A);
+}
+
+void loop()
+{
+  /* Reports the RTC  mode when it has been changed */
+  if (rtc_mode_changed) {
+    if (rtc.getBinaryMode() == STM32RTC::MODE_BCD) {
+      Serial.printf("RTC mode is MODE_BCD at ");
+    } else if (rtc.getBinaryMode() == STM32RTC::MODE_MIX) {
+      Serial.printf("RTC mode is MODE_MIX at ");
+    } else {
+      Serial.printf("RTC mode is MODE_BIN at ");
+    }
+
+    Serial.printf("%02d/%02d/%02d - ", rtc.getDay(), rtc.getMonth(), rtc.getYear());
+    Serial.printf("%02d:%02d:%02d \n", rtc.getHours(), rtc.getMinutes(), rtc.getSeconds());
+
+    rtc_mode_changed = false;
+  }
+}
+
+void alarmMatch(void *data)
+{
+  UNUSED(data);
+  Serial.printf("Alarm A Match! : change RTC mode at ");
+  Serial.printf("%02d:%02d:%02d \n", rtc.getHours(), rtc.getMinutes(), rtc.getSeconds());
+
+   /* Configure the new RTC mode */
+  if (rtc.getBinaryMode() == STM32RTC::MODE_BCD) {
+    rtc.setBinaryMode(STM32RTC::MODE_MIX);
+  } else if (rtc.getBinaryMode() == STM32RTC::MODE_MIX) {
+    rtc.setBinaryMode(STM32RTC::MODE_BIN);
+  } else {
+    rtc.setBinaryMode(STM32RTC::MODE_BCD);
+  }
+  rtc_mode_changed = true;
+}