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Robin Coxe coxe at close-haul.comHi Alexander. I took a look at the schematic last night. Protel is hard for me to read, probably because I'm not used to it. Overall, the board looks very nice. I have a couple of questions/comments: 1) Is there a particular reason why there's an external SRAM on the board? I notice that there is one on the Ettus N210 board as well, but do guys have a particular purpose in mind for it? The Spartan-6 FPGA has ample on-board Block RAM resources. If it's not strictly necessary, it would remove an ~$10 part from the BOM. 2) Maybe it was just because it was really late, but I couldn't figure out what was happening to the 1 PPS GPS timing pulse. How are you planning to use GPS information to discipline the 26 MHz oscillator? 3) One general recommendation: add lots of test points, particularly around the DC power sources, clock signals, and digital signals of interest going to and from the FPGA. Probing BGAs is a pain without them. Also, strategically placed ground test posts that you can use to clip on a scope probe ground connection will make debugging much easier. 4) 6.5 V is kind of a weird voltage. I'd be inclined to go with a 12V connection to an external power source, which would enable the system to be powered off a car battery, but this point is a matter of opinion more than anything else. -Robin On Tue, Oct 4, 2011 at 5:45 PM, Alexander Chemeris < alexander.chemeris at gmail.com> wrote: > Hi all, > > Attached is a new version of our schematics and PCB layout (note, they > may differ a bit with schematics being more recent). > Btw, I found diffpdf tool very useful for schematics comparison: > http://www.qtrac.eu/diffpdf.html > It nicely highlights changes, so you don't miss something. > > Our current plan for hardware prototyping is like this: > > 1. Most important parts of PCB layout should be done by the end of this > week > 2. Then we have 1 week (maximum!) to do any small changes to layout we > may want and fix bugs we (hopefully) find. > 3. Then 1 week for the final layout polishing, adding labels, etc. > 4. Final ACK for the layout and we push it to the fab for printing. > Manufacturing and delivery to Moscow will take 2-3 weeks. > 5. 1 week for assembly > > This is about 5-7 weeks and then we will have a lot of fun with > hardware and software debug. > > Robin, do you want to get an assembled board to participate in the > hardware debug session? :) > Btw, could you get a quote for the FPGA from Xilinx for 100pcs? > > -- > Regards, > Alexander Chemeris. > -- Robin Coxe | Close-Haul Communications, Inc. | Boston, MA +1-617-470-8825 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/umtrx/attachments/20111005/54d28406/attachment.htm>