SDRAM
Static RAM is simple to drive and has very fast random access characteristics but it’s too expensive to produce in large sizes and that’s where DRAM comes in. The part that I’ve selected is the 256Mb 16-bit Micron MT48LC16M16A2P-6A. As a single data rate (SDR) 166MHz device it should not be difficult to drive and won’t require the difficult PCB routing that you get with the recent DDR chips.
Flash
Here’s another one that I used before in the FPGA graphics accelerator project. It’s a 128Mb S25FL127S SPI serial part from Spansion. I know it well and I’ve driven it in the very fast 4-bit mode so I know what to expect from this one.
LEDs and switches
It wouldn’t be the same without a light or two to flash. Seriously though, FPGAs are not easy to debug and it can be invaluable to have the ability to just switch on a LED. There’s five of them on this board as well as a PCB button for user input.
Programming
Xilinx FPGAs offer a multitude of programming options. In my previous projects I’ve used the slave serial mode that allows an external intelligent device, in my case an MCU, to load up the FPGA configuration at boot time using a SPI-like protocol to the FPGA. This makes sense for a complete embedded design but doesn’t work for a development board where the JTAG connector is far more useful. I’ll provided one of those 14-pin JTAG socketed headers that will accept a standard IDC cable from a Xilinx platform USB programmer.
