I am using PSOC 5lp
SD card connection is emFile system.
Please refer to the emFile datasheet: https://www.cypress.com/documentation/component-datasheets/file-system-library-emfile .
The component provides an interface to the SD Card and can be used for communication with the SD Card.
In order transfer data using the USBFS component the following application notes might prove to be helpful:
You can also refer to the psoc3/4/5LP Code Example page for code examples on communication using USBFS component.
Can you please let me know if you are planning to utilize the the Mass storage class of USB?
It sounds like the optimum situation for you is to configure the USBFS interface as a 'passthru' for the SD card. In this case, plugging in the PSoC with this feature would appear as an logical drive (just like plugging in a FLASH drive). As another logical drive, you can access any file or directory as you would any FLASH drive.
Can anyone with more USB configuration experience help here?
I'm not a USB expert however I found this site that describes UMS class (=0x08) for USB access to mass storage devices.
It's a start.