How to speed-up bit file loading from flash

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On larger Spartan-6 FPGAs like the LX45 on Pipistrello the bit file loading from flash can take several seconds. However, there are ways to speed this up by changing some of the property setting for the bit file generation task.

Here are the steps in ISE to do this:

1) Bring up the project in ISE

2) Right-click on the "Generate Programming File" task in the processes window pane:





3) Click on "Process Properties", this will bring up a popup window like this:




4) Click on "Configuration Options"


5) Change the "Configuration Rate" from 2 MHz to max value (26 MHz), this will give a 13x speedup



6) Optional (Pipistrello only!)  The flash wiring on Pipistrello supports 4-bit wide data transfers so additional speedup can be achieved by changing the "SPI Configuration Bus Width" from 1 bit to 4 bits





7) Click OK and rerun the bit-file generation task to generate a new bit file which will load in a fraction of a second.








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Yep, good call. I thought about playing with those settings but never really had a big problem with the slow load time, not enough to bug me into doing anything about it.

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in the webshop, the Pipistrello boards are always sold out. Any idea when you'll make another batch?

I wonder whether you could convince Trenz Elektronik in Germany to stock them as European distributor, they also sell Xess and Digilent boards.

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Yeah, I sold all 100 boards in the previous batch and I got caught off-guard by the long component lead time now days, I guess the economy is doing good.  I do have boards on order, it just will take a little longer than the two weeks I was hoping for.


As for Trenz Electronics, sure I can check with them but they would probably want 30% or so for them which means I wont make any money at all :(

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OK, no hurry here. Can I pre-order in the webshop? I didn't try to submit an order with backorder items, maybe it works just like that.


Try Trenz, they sell a lot of other stuff at the same price as the vendor's own site. Somehow it has to work for them.

A regular distributor would make it easier to buy. For example, I can't order Papilios for work, the sourcing guys don't have paypal.


The Pipistrello looks like be the perfect lab board, GPIO headers, on-board USB, USB powered and the largest Spartan6 where I don't need a license and at a reasonable cost (take a FMC carrier S6 + GPIB breakout board for comparison, Pipistrello is half the price twice the FPGA size). I think they might be interested.

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