当rtc电池，晶振都正常的时候，rtc寄存器的访问是正常的。
如果把晶振去掉，然后读取rtc的寄存器的时候，程序在jtag下直接就死机，表现为：
Trouble Halting Target CPU:
(Error -1202 @ 0x0)
Device core is hung. The debugger will attempt to force the device to a ready state to recover debug control. Your application's state will be corrupt. You should have limited access to memory and registers, but you may need to reset the device to debug further.
(Emulation package 5.1.73.0)
请ti的技术支持指导下
