FFT MegaCore Function - burst mode data flow problems

[Altera_Forum]

Hi, 

 I am trying to use the FFT MegaCore Function (v8.1) for the first time. I am trying to operate in Burst mode, 256 point FFT with 16 bit precision and twiddle. I don't think I am correctly understating how the data flow between the source and sink is suppose to be.  First, the documentation is confusing. The waveform graphs seem to contradict the explanatory text. According to the text, when the sink asserts the sink_ready, the source can assert the sink_sop together with the first data sample. The waveforms in the documentation show the sink_sop being asserted right when the sink_ready is disasserted. What's up with that?  I've basically implemented the data flow according to the text. I assert the sink_sop right after the sink_ready is asserted by the sink. But then, immediately afterwards, I receive a source_eop with a source_error of 2h. I send 256 data sample and on the last data sample I assert the sink_eop. I then get the source_eop again with source_error 2h.  I've attached a .doc with signal tap snapshots. The signal tap is triggered on the sink_sop (count 0 on the signal tap). You can see the 256 samples of the sink_real signal being attempted to be loaded into the FFT engine. Right after the trigger (sink_sop), source_sop is asserted and an source_error of 2 is indicated.