Data buffers must reside in internal memory. EZ-Host's internal DMA engine can not access external memory. This means that all data buffers for USB, SPI, IDE, HSS and HPI must reside in internal memory. Any external DMA access attempts will result in the address wrapping around and the DMA engine will access internal memory and possibly overwrite vector tables or other important data/code space
In standalone development, if a Cypress design example supplied in the CY3663 developement kit is used, the linker script file (*.ld) will ensure the USB buffers get allocated in internal memory.