I was wondering if some insightful minds might be able to tell me what sort of costs I would be looking at to produce a single PCB similar to this: http://www.openmobilefree.net/?p=1839
I'm able to obtain various fpgas used for relatively cheap (nice chips). I wanted to build a dev board that had an onboard jtag, usb, power, and 50mhz clock. I wanted the remaining unused FPGA pins to be available for re purposing later on (as seen in the site above). My problem is that the chips will be in different sizes, sockets, layouts. It shouldn't be very hard to route the 50mhz GPIO clock and jtag to where they're supposed to go. But that requires a completely new board. Would it be possible to do a base design then quickly change the design and print 4 or 5 boards at low cost depending on the pin-out?
Fail.....
1. You don't route the tracks where they want to go, you route the internal logic to the relevant pins.....
2. EVEN for the same major part number (lets say xilinx) with the SAME package, the control pins of the FPGA may be routed differently.
3. The power connections are located differently
pull this from Xilinx (ug195.pdf) take a look at the pin differences for package FF1136.
Your 'standard layout' is fantasy, absolutely the MAXIMUM you could get away with, would be a TWO sided PCB with BGA matrix & PTH tap off points.
You would then have to HAND place the Inductors/Capacitors, power connections and then hardwire any I/O clocks you need.
This would be the result:
http://www.chiaki.cc/Pyxis2010/images/pyxis2010-fpgasol2.jpg
http://www.chiaki.cc/Pyxis2010/images/pyxis2010-fpgasol1.jpg
I guess my OP was TL;DR?
I specifically said it would require a different board for each chip with different pin outs. That is what I wanted to know. How much would it cost to change the pin outs between printing but keep the components on board the same. The same jtag, usb, power, clock will work for all of the chips but the chip pin-out is different (As I said). I was wondering what It would cost to create just a few board for each chip.
For instance, I just picked up 3x EP4SE530 for 100$ a pop. If I can put them on boards for 100$ea I can have 1.8GH/s (assuming it has routing available for a full 9 cores) for 200$ea and still have it be repurposable later on when I stop using it for bitcoin mining by having unused pins being available for add-on mods. But later on I might get another chip; so I'd need to re-lay out all the pins in the PCB design so they're routed to the correct pins, print a new pcb, and then use that PCB with my new chips. (At 20-40 watts it's almost as power efficient as an avalon.)
Found this on another thread here: http://www.seeedstudio.com/depot/fusion-pcb-service-4-layers-p-1383.html?cPath=185
But i'd still need to get the components on the board at that point.