踏着时光去旅行的博客

1. 系统框图HXTAL：高速外部时钟；LXTAL：低速外部时钟；IRC8M：高速内部时钟；IRC40K：低速内部时钟；2. 时钟树/*! \brief get the system clock, bus and peripheral clock frequency \param[in] clock: the clock frequency which to get only one parameter can be selecte