Getting started with FPGAs

Like a lot of engineers I was first exposed to FPGAs back in university. A number of years have since passed and most of the stuff I learnt I have since forgotten. At the time FPGAs were mysterious devices that cost a fortune and where insanely difficult to program. Fast forward some 10+ years and technology has moved on. These devices seem to be appearing more and more and not only in commercial products but in peoples personal endeavours as well. Development boards although still expensive when compared with those for micro controllers are coming down in price. So I decided it was high time I got myself a board and got up to speed.

Choosing a board wasn’t a simple task. Although the FPGA market appears to be dominated by two players Altera and Xilinx. Which to choose? For me it came down to the quality of the tools and support. Both offer free versions of their development tools but after reading numerous reviews, articles and blogs I had a slight leaning towards Xilinx. No particular reason I just felt their tools were a bit fresher, had less limitations and the support Xillinx provides appears to be first class.

After much deliberation I decided on the Papilio FPGA development board. The Papilio is an open source FPGA development board that comes in two flavours (technically its three). The Papilio One which contains a Spartan 3E FPGA (in 250K and 500K gate count) and the Papilio Pro which contains a Spartan 6 LX9 FPGA. Both boards are minimalistic in design.  The Papilio One in addition to the FPGA contains an on board power supply with selectable I/O voltage and two channel USB connection for JTAG and serial communications. The Papilio Pro also features an on board power supply, USB connection and an additional 64Mbit SDRAM.

Additional hardware maybe added in the form of wings. That way you can purchase wings to support the features you require and not be lumbered with things you don’t. This allows you to cut down on initial layout costs. Being open source the Papilio hardware has huge support in on-line forums.

The Paplio One 250K version is available from Gadget Factory for $37.99, the 500K version for $64.99 and the Papilio Pro is available for $84.99. Even when you take into account shipping costs and currency conversion these boards still represent excellent value for money.

Papilio One

I decided to order the Papilio One 500K version and the additional Logic Start mega wing. The Logic Start mega wing contains a 7 segment display, VGA port, mono audio jack, micro joystick, SPI ADC, 8 LEDs and 8 slide switches. Great for getting up and running and experimenting.

Just over a week later and the board arrived. Not bad considering this is coming all the way from the United States to the UK.

In the mean time I had already installed the Xilinx ISE Webpack development suite as well as downloading the “hello_word” bit file and the Papilio loader tool. The next stage was to brush up on my VHDL. I decided to start with VHDL as opposed Verilog since VHDL appears to be more popular in Europe than Verilog. Realistically a good FPGA engineer would be expected to be sufficiently competent in both VHDL and Verilog but everyone has to start somewhere.


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