[time-nuts] Time tagging fpga

Anders Wallin anders.e.e.wallin at gmail.com
Sat Nov 22 03:12:16 EST 2014

On Sat, Nov 22, 2014 at 5:37 AM, Robert Darby <bobdarby at triad.rr.com> wrote:

> I finally got the time tagging fpga I was playing with to a semi-usable
> state.  I mentioned in an earlier post that I was unable to compile or link
> the FTDI library but Magnus Karlsson very kindly rewrote a program of his
> to provide me with a utility to set up the USB asynchronous parallel
> interface characteristics on the PC.  Only bad thing is you're running
> blind so it pays to do a short run to make sure all's well before
> committing to a long capture.

Interesting! How do you generate a clock (what frequency) for the FPGA?
Are you using a coarse-counter + interpolator (delay-line?) approach?

I'm planning to explore this with a Pipistrello (sparta6 LX45) board, which
has the same fpga used in this work:
the VHDL is available on ohwr:


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