STM32429 Discovery SATA communication.

Very interesting task, but I'd ask your professor what they mean?  SATA is a very high speed serial bus, where the slowest version operates at 1.5GigaBits/sec.  There is no interface on the STM32F4 series of microcontrollers that could interface to this without and external controller.  Of course most of the existing controller chips have a SATA bus on one side, and USB on the other.  You could use one of these and read the SATA drive through the USB interface on your eval board, but it seems that this is the opposite of what has been assigned.  If they want you to build an external interface using an FPGA or some other logic to work with the SATA interface, that might be doable but rather impractical based on the existing chips that do this.

In any event a first step might be to look at the actual SATA specification documents, and perhaps at the data sheets of existing SATA to USB adapter chips.  They may at least give you an idea of what you need to do.  On the USB side, I would assume they want you to have the USB port on the chip act like a USB drive to the attached host system.  This is the inverse of some existing middleware provided by ST, which enables you to easily connect an external USB drive to your microcontroller.  again an interesting task.

If you go to the Wikipedia page on Serial ATA the references at the bottom should provide a good index as a start point.  This is a link to a pdf of the Rev 3.0 spec:

http://www.lttconn.com/res/lttconn/pdres/201005/20100521170123066.pdf

and here is a link to a data sheet of a TI chip that does what you are being asked to reinvent:

http://www.ti.com/lit/ds/symlink/tusb9260.pdf