Over the last few months I’ve been trying out a number of low cost FPGA development boards with the view to how easy new people can get involved. FPGAs and the languages like VHDL and Verilog are not the easiest things to learn and a good kit make a lot of difference. In this post I look at the Papilio One which can be purchased via the GadgetFactory.net.
The main board comes in one of two options. Both boards are the same apart from the Xilinx chip fitted. The smaller board has the 250K (XC3S250E) and then there is the large 500K chip option as well. The board is supported by a EEPROM that you can load and program the configurations files into. This allows you to run the board without having to program it every time. Power is supplied via either the USB connector or a jack plug. The USB allows for programming and access to a UART onto, into the board via a FTDI 2232. On board regulators and selection of IO power is via jumpers and whopping 32Mhz clock is also supplied.
Left to right - Joystick interface, VGA, microSD, PS/2 and Audio Wings
The IO is arranged in Wings, like a butterfly! Each section contains 8 IO pins as well as power rails. In total there is 48 IO pins which is large enough for most applications. You can then plug in wings or expansions boards into the main board and use as required. I was supplied the LED/Button boards as well as the, Joystick IO board, VGA IO board, Audio, Memory card and PS2 keyboard / mouse board. I was also supplied the Arcade Board which I'll come back too. All the boards are open source like the main board so finding drawings is easy on the site.
The getting started guide can be found on the web site and this guides you though plugging in the board and in my case windows auto detecting the PCB, then on to downloading a demo. This works by flashing the LEDs and buttons and all worked very well. I then moved onto the arduino demo, this is where you can download the papilio distribution of the arduino IDE. Basically you can program the Papilio One just like an arduino. All great and worked well first time but I wanted to get more into the FPGA side of it.
At first I did not find an FPGA or VHDL / Verilog guide until I was looking for something else and fell upon it. However I was not totally impressed to be honest as it was quite short and basic. I would have liked worked examples of using the wings on the board. Yes I could go on and do this myself as I do know VHDL but keeping to the new user view point I decided to try some of the demo code I did find under the Projects area.
Something I’d not done myself is drive a VGA screen with any electronics so looking in the project area was excited about what I saw. Here you will see a nice demo of driving a monitor via the VGA wing - however I’ve not got it working for some reason and need to get my head around it as to why. This is not good news if your new as you want nice working examples you can then tweak.
I then moved onto the arcade wing which is larger than the main board and comes with two joystick interfaces, VGA output, Audio etc. From the site you can see people playing pac-man and this looks again very cool. However I was again disappointed to not get it working. Its not that there is anything wrong with the Dev Kit or the wing, just not great examples. I felt that I would have to understand more about VHDL and FPGAs to use this kit to its full potential.
I then took some time to re-look at the site and consider what the Papilio is and I took some time to talk to them directly. You see the Papilio is taking a different tack than some Development boards by introducing FPGAs though the easy to use Arduino IDE. One of these methods is by added to the Arduino core by adding FPGA code to it. Alternalivly you can also consider using the ZPUino which is a open source CPU, again programmable via the Adruino IDE.
Personally I’m still undecided if I like the Papilio One or not. For me I was looking for a easy to use and learn FPGA board but found that the designers have taken a very different approach to doing this. Personally I think if your looking to go into FPGAs and expecting to use something like the Xilinx IDE then this is not it, and this is only because of the documentation in my view. However if you used to the Arduino and like the methods they have come up with then I’m certain you will find all you need on the site to get you started.
Software is however only one side of a development kit and the hardware itself also has to be well designed too. The board and the wings are very good quality and the tests I have done have show it to be great. So is something that I’ll be keeping close by to play with and use myself.
