This is a RTC additional function. This is only for Nucleo F401RE & F411RE mbed(Added L152RE, F334R8, L476RG & F746xx). If you connected battery backup circuit for internal RTC, you can make a power-off and reset condition. RTC still has proper time and date.

Dependents:   Nucleo_rtos_sample PB_Emma_Ethernet

Please refer following NOTE information.
/users/kenjiArai/notebook/nucleo-series-rtc-control-under-power-onoff-and-re/

Revision:
8:88d30761683b
Parent:
2:765470eab2a6
Child:
12:4074fe3e67c7
--- a/modify_info_L152.h	Sat May 16 00:34:50 2015 +0000
+++ b/modify_info_L152.h	Sat May 16 01:55:33 2015 +0000
@@ -20,7 +20,8 @@
 //*************************************************************************************************
 //
 // (1) Update mbed-src library if you want
-// (2) File rtc_api_L152.c copy to directry /mbed-src/targets/hal/TARGET_STM/TARGET_NUCLEO_L152RE/
+// (2) File rtc_api_L152.c copy to directry
+//     /mbed-src/targets/hal/TARGET_STM/TARGET_STM32L1/
 // (3) Delete rtc_api.c in the same directory
 // (4) Edit rtc_api_L152.c
 //      (a)Delete 1st line