F5XX RAM 存储器根据RAM空间的不同，分为多个Section 每个Section 4k
　　　　　　　 拥有四种模式。每个Section 关闭可以由RCCTL0 来控制，一旦某个section
　　　　　　　　　 被关闭后那么以前存储的数据都将丢失，对已经关闭的SECTION 进行写是没有效果的，被关闭RAM SECTION 部分读为0；(F5XX RAM memory is divided into several Section, each Section 4K according to the different RAM space.
There are four types of models. Every Section shutdown can be controlled by RCCTL0, once a section.
After being closed, the previously stored data will be lost. Writing on the closed SECTION is ineffective. The RAM SECTION part is read as 0.)