Check RTC LSE(External Xtal, 32.768kHz) mode

Dependencies:   mbed CheckRTC

Please refer follow links.
My notebook
http://developer.mbed.org/users/kenjiArai/notebook/nucleo-series-clock-structure-and-xtal-oscillation/
Q&A for RTC Xtal
http://developer.mbed.org/questions/4531/RTC-External-Crystal-Nucleo/

Committer:
kenjiArai
Date:
Sat May 16 23:38:13 2015 +0000
Revision:
4:56a0cbad89b0
Parent:
2:8b6a8cfa173a
STM team has changed start-up time but still has a problem. Simplified a checking procedure.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
kenjiArai 4:56a0cbad89b0 1 http://mbed.org/users/mbed_official/code/mbed/builds/dbbf35b96557