5438UCS模块的疑问

francis_hao

5438UCS模块的疑问 [复制链接]

5438的时钟，在产生错误的时候文档上是这么说的：

If a fault isdetected for the oscillator sourcing MCLK , MCLK is automatically switched tothe DCO for its clock source(DCOCLKDIV) for all clock sources except XT1 LF mode.If MCLK is sourced from XT1 in LF mode , an oscillator fault causes MCLK to be automaticallyswitched to the REFO for its clock source(REFOCLK).This does not change theSELM bit settings. This condition must be handled by user software.

时钟会自动切换，但是又说要在用户程序中操作SELM。这不是矛盾了吗？应该是什么意思呢？
谢谢！