FPGA Implementation of a SD Card Controller using SPI communication

The Field Programmable Gate Array (FPGA) devices are being used more and more, especially in applications that require real-time data processing, for example in communication systems. To meet the memory requirements for FPGA systems, the onboard memory can be used, but it cannot be expanded easily by adding some cards. More useful are Secure Digital (SD) cards that are detachable and can be replaced easily. In this paper, we have designed and implemented a FPGA controller that allows writing and reading SD cards using the SPI protocol. The main objective is to provide a storage solution for FPGAs, to store large files on large capacity, cheap, portable and easy to use storage devices. Using the SPI protocol, the system can access multiple SD cards with a minimum usage of data lines from FPGA. The hardware design and implementation are developed on a Xilinx AC701 platform with Artix-7 FPGA, using VHDL language. The FPGA controller was tested with more SD cards and the results shown that the system can run without errors.