Each sample application contains a p2_init() function that gets called before uC/OS-II starts. Since not all OS services are available, only the following operations are permitted in p2_init():

• Initialize global variables - e.g. by direct assignment or by using C functions such as memcpy, or memset.
• Create semaphores - e.g. calling OSSemCreate() or OSMutexCreate().
• Initialize tasks - e.g. calling OSTaskCreateExt(), OSTaskNameSet().
• Install callbacks. 

Some things you should not do:

• Call other OS functions
• Print to the CLI
• Interact with peripherals or the filesystem
• Make other API calls

Operations not permitted in p2_init() need to be done in your tasks before the while(1) loop. If Task A requires Task B to do something, then a semaphore should be used to provide synchronization.