Saturday, April 4, 2009

Board Bringup

Well, I have made some progress. I have at least one board with an fpga that i can program from my PC.
You can sort of see in the picture that 3 of the 4 leds are illuminated. I wrote a small core for the FPGA to test the two SRAMs that I soldered on. The top one is passing (led #3), but the bottom one is isn't (led #2). led #1 tells me that the test did start and led #4 signals that the test finished. It's just a sanity check (does two writes and checks the first one), I need to do a real integrity check soon.

Not sure what's wrong, yet. I'm hoping It's something simple, like I fried the sram chip, then I can just slice it off and solder up a new one. I guess it's not that big of a deal anyway, I should at least be able to test it with just the 2mbyte of sram. That's more than I had on the de2 at least. Plus I can still solder one more for another 2mbyte.

jeeze it's late. gonna head to bed and head back to my lab in the morning.


  1. come on it was only 1:13 i stayed up till 4 am :D

    but nice work && nice leds.. ;)

  2. there's actually something going on with the timestamps. When i posted that it was roughly ~5am

  3. We are working on a similar project. Not FPGA based, just a little proof of concept using a mcpu and 74er logic chips.

    Hope u get ur boards working :-)

  4. Reminds me of Blizzard's SNES development station...

  5. Wow, that's some A+ soldering there man, I wish I could do that!

    Did you run flux over the pins, then just wipe solder over it, or did you use a oven?

    Also, good luck on getting that second s-ram chip going!

    (Perhaps one of the red wires you hand-soldered to the chips is shorting a nearby pin, causing the error? Even if you don't think this is the case, it couldn't hurt to check!)

    -Ed the Nerd ;)

  6. @Ed I have fancy magnifiers and stuff in my lab. So unfortunately (or fortunately?), i can quickly rule out simple problems like a solder bridge or a crossed wire.

    In terms of soldering, I think i'm improving. The FPGA was soldered in a reflow oven, but I had to rework it a bit by hand with a soldering iron. The memory chips were done by hand with an iron, flux, some copper wick and a lot of patience.

    I'm stalled right now as I wait for some more parts to arrive, but I'm hoping I can now solder the FPGAs by hand as well. We'll see, I guess.

    I will probably end up redesigning the board eventually, so even if these boards turn out to be a complete failure, I have learned enough with this project to continue moving forward. So that's good, I guess.