I'm working with the FX3 DVK, following the application notes AN65974 to perform stream_in, stream_out and loopback transfer with my Xilinx FPGA. When performing stream_in and stream_out transfer, it seems quite ok.
However, during loopback transfer, after transfer data out, when I was trying to read data back from bulk in endpoint, it shows that zero length data transfered. I tried to capture how each control signal data react from FPGA side during transfer. I found that sfter SLOE# and SLRD# were both asserted, no data came out from FX3, my FPGA did not recieve any data, flagc and flagd remained 1.