PCB with Spartan 6 schematic

[sphare]

Hello. I have to design a PCB project with Spartan 6 FPGA. It should be a SD Cards Controller with 8 SD cards working together - creating one external memory area (if any of cards is missed or broken, device should be working). What should the project contain apart from a Spartan6 FPGA, SD sockets and a power system (from USB) ?

 

[ArticCynda]

Why would you want to connect them to a Spartan 6 FPGA? Wouldn't it be much more convenient to wire them to a microcontroller (or two microcontrollers, if you like the redundance) and control their chip select lines with MCU GPIOs? You can then do with a smaller FPGA for your DSP needs, which will be a far cheaper and easier to implement solution.

 

[sphare]

It's not up to me, I can't change this concept.

 

[ArticCynda]

SD cards readily accept 3.3V so if you set the VCCIO of the Spartan 6 to 3.3V then you can hook up the SD card sockets directly to the Spartan 6 GPIO. I'd recommend putting small series resistors (22 - 100 Ohm) in series to reduce the EMI, but aside from that there shouldn't be too many issues arising. Card Detect and Write Protect need pullups if you want to read them in.