Dangerous Prototypes

In the beginning of december, Numato Lab (http://http://numato.com) added two new FPGA boards to their offering - Mimas (http://http://numato.com/mimas-spartan-6-fpga-development-board) and Saturn (http://http://numato.com/mimas-spartan-6-fpga-development-board). Tom from NumatoLab was so kind to send me one of each, kind of a late Christmas present. They arrived on the second of January, and I had some spare time since then to test them a little bit. So I took the time to write a review for both FPGA boards (http://http://blog.hendriklipka.de/archives/2014/01/numato_fpga_saturn_mimas_boards.html).



They are little bit smaller than the existing Elbert (http://http://numato.com/elbert-spartan-3a-fpga-development-board) board (seem my previous review (http://http://blog.hendriklipka.de/archives/2013/05/elbert_fpga_board.html)), though they pack much more punch - both are Spartan6 boards. Both come with a LX9, but Saturn is available in different configurations up to a LX45.

The original Elbert board was explicitely designed for FPGA first timers, and is not really suited for more complex projects (due its limited amount of available GPIOs). So I was curious to see how the new boards stack up against it.

Mimas seems to be the better board for the advanced FPGA beginner - it's not so expensive, and comes with onboard push buttons and LEDs to aid first designs (and debugging). Saturn in contrast is more for the power user - it comes with 512MBit SDRAM, and breaks out nearly all GPIOs (depending on the configuration up to 150).

Both can be programmed via USB, with a configuration upload program from Numato (available only on Windows). Additionally there are JTAG headers on the boards (a 2x3-one on Mimas, and a 2x7 one on Saturn). Unfortunately the JTAG connector on Saturn only looks like its a standard pinout - it swaps TDI and TDO, so be careful. Also, pin 1 is nor marked there, so one needs to remember how to insert the cable.

Apart from this, the boards are really nice. They are small, and don't come with unnecessary stuff on board. So if you are looking for a small, inexpensive yet powerful FPGA board, look at them.

I bought one of the Saturn boards (xc6slx9) and won another through their new year give-away. I'm a newbie when it comes to FPGAs but found their Verilog tutorial (http://http://numato.com/tutorials) very helpful to get started. The IO pins didn't provide enough current to power simple LEDs so I had to use transistors to drive them.

The Saturn uses LPDDR memory, for which you need to use an IP core from Xilinx, though it comes for free with the Webpack ISE license. I looked at the memory interfaces from opencores and it should be possible to adjust the DDR memory core to use this particular memory chip, though I'm far from experienced enough to even start looking at this yet.

Schematics and board layout for KiCad are provided on the numato website so the board is fully open source hardware. A good number of IOs are length matched for differential IO, which should make the board usable for things like HDMI or PCI-X.

If anyone has any suggestions for a good book or web resource to learn more about FPGAs in general or Spartan6 in particular please let me know :)

I can suggest looking at the books (http://http://www.freerangefactory.org/site/pmwiki.php/Main/Books) from FreeRangeFactory. There are several eBooks taking on topics such as digital design in general, using VHDL for PFGA programming and one about using the Xula boards (its for the Spartan3A boards, but its the most hands-on guide).

Thanks hlipka for the suggestion. The books look great, and their additional content on the site also looks to be very interesting.
I also found asic-world.com (http://http://www.asic-world.com) and fpga4fun.com (http://http://www.fpga4fun.com) to contain very useful information. Especially fpga4fun seems to be especially tailored towards enthusiasts.

I'm thinking about designing an HDMI shield for the Saturn with two plugs connected together through the fpga so you can look at the data that's going through the "cable" and potentially save it to a disk (to do HDMI recording where it's normally not allowed) or do some modifications like generating on-screen overlays (maybe a banner at the top or bottom showing emails, tweets or breaking news).

I don't really have any experience with circuit design yet but I hope connecting two plugs to a row of headers isn't too difficult even if the traces have to be length matched (no sure if that is required for HDMI). Numato published the KiCad files for the board so I guess I can use this as a start for an add-on shield since the board size and header layout are already done...

HDMI intercept is not trivial.

http://hackaday.com/2012/01/21/overlayi ... nnections/ (http://hackaday.com/2012/01/21/overlaying-video-on-encrypted-hdmi-connections/)


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Just an quick update to that: Numato labs has now introduced a range of breakout boards (http://http://blog.hendriklipka.de/archives/2014/04/update_numato.html) designed to fit their FPGA boards. And they are giving away some of them each week...
There is also a new FPGA board - this time just a FPGA breakout with a Spartan6A LX45 on it. Its just 40x36.5mm...