有3种方式可以加快wakeup的流程
1. This chip supports an optional feature that bypasses SIRC trimming, FIRC trimming, PMC trimming and DCM scanning phases in case of Standby mode exit sequence by writing 1 to DCM's DCMRWF2[6], DCMRWF2[5], DCMRWF2[4], and DCMRWF2[3] fields respectively before Standby mode entry for bypass operation.
This results in a considerable reduction in Standby mode exit duration. The trim values are retained across Standby mode and bypassing these values does not cause any impact.
通过减少一些不需要重复的配置流程，可以加快启动
2. 除了上面的设置可以加快速度,还可通过使能PMC.CONFIG[LPM25EN](bit3),即不关闭V25的供电，使得FXOSC能够在退出standby后快速恢复,但是显然，会增加相应的功耗
3. 还有第三个地方可以加快速度，PMC.CONFIG[FASTREC](bit2),简单来说，就是启动的电容同时充电，对电源的供电能力比较高，大概是正常启动电流的3倍。