1) Please clarify what do you mean by data didn't transfer. I suppose the device enumerated on the PC and came up as a imaging device.
2)Connect a USB-UART bridge and check which FX3 API is getting failed. Please put debug print to count the number of producer and consumer event. Please report what do you see on the UART.
2 situation first for AN75779 sample change to 32bit: 1)device enumerated on the PC and did transfer few image data (traced by Bus hound) then stoped 2)im using cyusb3kit board to debug then i see the thread "tx_thread_schedule" & "tx_thread_system_suspend" is running. change back to 16bit it should be "tx_queue_receive" & "txe_queue_receive" & "CyU3DmaThreadEntry" & "tx_thread_shell_entry" second one is use example in http://www.cypress.com/forum/usb-known-problems-and-solutions/fx3-firmware-streaming-uvc-data-fpga?source=search&keywords=uvc%20with%20slavefifo use AN65974 fpga_StreamIn example to genrate fpga data but the device enumerated but no data transfer system run in txe_thread_relinquish thread