I've uploaded the SPI Flash schematic to git. I'll do a video discussing this schematic & the connections between the Flash and the FPGA device @ the top level and how that ties into the backend Arduino and any other top-end boards you might...
Uploaded files to my git repository with the JTAG wiring completed. Video to follow. The basics are pretty straight forward:- Broke out JTAG signals- Add pullups to ensure JTAG is always in a known state- Add terminations - Generate...
FPGA decoupling can be tricky to sort out without some guidance. Thankfully, Xilinx provides a pretty comprehensive PCB Layout guide that has specific recommendations for decoupling schemas for the PCB, based on specific parts and pin counts. I...
Uploaded a heap of stuff to git. Working on video now. This includes two layers of top level documents that show sheet to sheet connectivity between SPI and the FPGA and also have the breakout for the FPGA IO and other various items. Added...
Updated the schematic over the weekend to clean up the wiring and group signals, sheets, etc. more intelligently. A new version of the source files and a PDF can be found on the git repository. A direct link to download the PDF can be...
Uploaded video no. 3 explaining the schematic overhaul, JTAG wiring (w/ a little background on JTAG - though focused on the implementation), and discussing the decoupling. For a detailed discussion of JTAG, I suggest having a look at...
Made a number of little tweaks this weekend and uploaded a new SRAM document, new SPI multiplexer doc, made tweaks to the top level to integrate these elements and just finalizing some bits here and there. Complete details in github. See...
Uploaded video number 4 to Youtube, showing both SPI Multiplexing with a TI Bus Switch, and also implementing Asychronous SRAM (128K x 16). Next up, power supply!
Had some fun tonight playing around with PCB routing. You can see in the PDF in git or the PCB file (you'll need altium to open it) that I'm all about "pretty". :) Still a fair bit to finalize the routing and design and such but moving...
Uploaded the power supply design to git hub today. The supply is laid out in a way to allow either driving the system from the Arduino's 5V supply or using an external power adapter. The Arduino's 3V3 supply is tiny (very little current,...
Uploaded the layout files to git today with routing completed and some final schematic tweaks. Released gerber files also to fab. Design is looking pretty good and should be pretty close without many major changes since last prototype I'd...
Released a complete collection of manufacturing outputs including Gerber, NC Drill, ODB++, Testpoint files, & Pick and Place. All of these are for building proper prototypes. Expect to have boards in 5 days. 2 Days for assembly, a day...
Made a cosmetic change the schematic (top level) and also uploaded PDFs to Git. One small change to PCB was required to get the cost down (increased via hole dia for QFN LDO from 2mm to 2.54mm...makes "low cost" standard mfg avail)
...But it's enough for the board house to balk at, even if they can't mfg to those tolerances. Oh well, released a slightly modified Gerber to deal with some "roundingness" in the mfg outputs and ensure things are a little cheaper overall (under...
I went ahead and added feedback from the fpga DONE pin via the addition of a status LED. Also added a jumper that enables that feedback to be sent back to the Arduino board. The jumper gives the option to route the DONE pin to the Arduino...