5509a, McBSP and one frame sync

Hello,

I've been trying send 32 bits data to McBSP asychronously. Just generate one 
frame sync internally and then send 32 bits data. I'm using external clock.

Now frame sync comes all the time and even the 32 bits are sent many times 
even I sent it once.

How to configure? Is there any way to do it?

Thanks,
Parru