What is the precondition of the FCCU transtion from Normal Mode to Config Mode?

[liujinhang]

I know one of the preconditions is the NCF_Ss must be cleared all before transition. But in my test, somes time i found that the transition failed when NCF_Ss were all zero read from debugger.

so i want to know is there any other predconditions of the FCCU transtion from Normal Mode to Config Mode ?(except from 'clearing all NCF_Ss')

[davidtosenovjan]

See following document, chapter 6:

https://community.freescale.com/docs/DOC-329719

Also it is needed to realize that sequence normal->config->normal must not be interrupted (also you cannot step this sequence by debugger).