完美解决了.
默认的就是外部时钟源噢。如果外部没有接32K的，需要更改hal_board_cfg.cfg文件里面的设置。
* hal_board_cfg.h
/* ------------------------------------------------------------------------------------------------
* Clock Speed
* ------------------------------------------------------------------------------------------------
*/
#define HAL_CPU_CLOCK_MHZ 32
#define OSC32K_CRYSTAL_INSTALLED FALSE // 插入此行!!!!!!!!!!!!!!!!
/* 32 kHz clock source select in CLKCONCMD */
#if !defined (OSC32K_CRYSTAL_INSTALLED) || (defined (OSC32K_CRYSTAL_INSTALLED) && (OSC32K_CRYSTAL_INSTALLED == TRUE))
#define OSC_32KHZ 0x00 /* external 32 KHz xosc */
#else
#define OSC_32KHZ 0x80 /* internal 32 KHz rcosc */
#endif