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:
14:78e453d7bb85
Parent:
13:44e5327acb05
--- a/modify_info_L476.h	Fri May 27 20:16:09 2016 +0000
+++ b/modify_info_L476.h	Sat Jul 02 03:00:33 2016 +0000
@@ -6,7 +6,7 @@
  *  http://www.page.sannet.ne.jp/kenjia/index.html
  *  http://mbed.org/users/kenjiArai/
  *      Created: May       28th, 2016
- *      Revised: May       28th, 2016
+ *      Revised: July       2nd, 2016
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
  * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
@@ -20,7 +20,7 @@
 //*************************************************************************************************
 //
 // (1) Update mbed-dev library if you want
-// (2) File rtc_api_L152.c copy to directry
+// (2) File rtc_api_L476.c copy to directry
 //     /mbed-dev/targets/hal/TARGET_STM/TARGET_STM32L4/
 // (3) Delete rtc_api.c in the same directory
 // (4) Edit rtc_api_L476.c