[time-nuts] FPGA GPSDO (Was: Re: NTP jitter with Linux)

Jim Lux jimlux at earthlink.net
Sat Apr 7 18:29:23 EDT 2012

On 4/7/12 8:57 AM, Chris Albertson wrote:
> If you are looking for free soft core CPUs for use in an FPGA then look here:
> http://opencores.org/projects
> Look under "processors" for many CPU cores.   They also have some
> Eithernet controllers you'd need.
Like all things opencores/sourceforge/etc  you need to examine whats out 

We've used a SDRAM controller from opencores (and modified it for our 
puproses) and it works pretty well.  Some other stuff, maybe not so 
finished and ready for use.

It all depends on provenance....

To blow our horn a bit, we've got some useful building blocks available 
for free.. We are targeting Xilinx Virtex II, but they're designed to be 
pretty generic Verilog for any target.

If you need a 64 bit timer core with a bunch of latches and a 
programmable pulse generator, let me know.  We've got one at JPL we're 
happy to distribute (for free).

Goddard Space FLight Center has a variety of SpaceWire cores (in VHDL), 
and we've got a Verilog wrapper for it at JPL.

Simple cores to do things like record samples from an ADC into a giant 
SDRAM buffer or play back samples from SDRAM into a DAC, we've also got. 
  You want that digital oscilloscope or ARB with a 10s of MegaSample 
buffer.. we've got it.

Gaisler has a lot of useful, well debugged, cores for free.. Ethernet, 
RAM controlkers, various other peripherals.

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