Many years ago, as a college student, I designed and built an audio digital delay using TTL logic and 64k of dynamic RAM, reclaimed from an old PCB. It was a beast - it had 8 bit converters, and control waveforms were generated by a 32x4 PAL chip, which I programmed with DIP switches. It sounded, erm, special, with lots of odd warbling and whistling noises - but it probably had so much ground bounce and other problems that, well, it was amazing that it worked at all. And it earned me a distinction, which was a big deal for me back then.

Time and digital electronics have come a very long way since those days. I've done many projects with PIC microcontrollers, but that is different from designing with registers and latches. These days you wouldn't dream of building anything with discrete IC's of course. Now it is all about CPLD's, FPGA's and hardware description languages - much of which has somehow passed me by.

Mimas V2 FPGA card

I decided to brush up my skills, so I started looking for am FPGA demo board to play with. Xilinx make some of the most powerful FPGAs around. The Spartan 6 series boast tens of thousands of configurable gates, along with sophisticated sub-systems such as DSP slices, DRAM interfaces, the possibility to program in a custom microcontroller, and so on. The problem is price; the dev kits for them start at about 300€. More than I wanted to spend, but there are a few smaller companies making inexpensive alternatives. (You could also learn Verilog or VHDL using one of the many free simulators out there, but then you miss out on the satisfaction of running on real hardware.)

The board I went for is called the Mimas V2, and it is made by some guys in India called Numato. The price is very reasonable at 46€, and it has some nice features. There are enough switches and LEDs that you can do a lot of playing without adding any peripherals, there are lots of expansion headers, and it can also produce VGA video and some kind of audio signal. They have also designed it so that you can program it with Xilinx's free tools and a standard USB cable, instead of the expensive JTAG cables from Xilinx. (There is a header for JTAG if you do want to go that way.) They also have some decent tutorials on their site, good for the complete noob (like me).

So I placed the order, and two days later the board arrived. Build quality and service both great so far. Later that day I had the Xilinx software installed, and with the help of this excellent pdf tutorial as well as the ones on Numato's site, I managed to get things working.

I did have one issue; programming the board was a bit flaky. Sometimes it would work, sometimes there were errors showing in the config utility. I did the usual re-installing of drivers, swapping cables, and so on, and then raised a ticket with Numato. Their rep Tom got back to me very soon, and we tried a few things to resolve the issue, before deciding that there must be some sort of intermittent problem with the board. Well, it can happen, so no drama. Without being asked Tom offered to ship me a replacement board. So I can officially say - they are a great company to deal with. Thanks Tom!

Verilog has a steepish learning curve, but I am making progress. I am not sure if I will ever re-create my fabulous 1980's digital delay on this thing, but I'll have some fun trying, and no doubt learn something useful.