[time-nuts] Shera revisted

[bownes]

There are also some nice cypresses semiconductor parts that are similar and have a really nice dev environment. 
Basically a core surrounded by programmable logic. Code in C ore close to it. 



> On Aug 11, 2016, at 07:06, Bob Camp <kb8tq at n1k.org> wrote:
> 
> Hi
> 
> To your earlier point, there are a number of fairly low cost boards with Zynq’s on them. 
> They aren’t into the $5 range, but they are not that much more than one of the Beagle 
> boards. 
> 
> Bob
> 
> 
>> On Aug 10, 2016, at 11:18 PM, Chris Albertson <albertson.chris at gmail.com> wrote:
>> 
>> Thanks for pointing out the Zynq.  Wow you get a dual core ARM and an
>> FPGA all in one package.   It seems overkill for a GPSDO but not the
>> type you are making as you can transferring the time out of the GPSDO
>> using PTP.
>> 
>> The Zyng looks to the the perfect platform for low-cost SDR.
>> 
>> On Wed, Aug 10, 2016 at 2:30 PM, Joakim Langlet
>> <joakim.langlet at seaview.se> wrote:
>>> Dear time-nuts,
>>> 
>>> My name is Joakim Langlet (SM0OET) and I just recently joined this list. As
>>> Brooks Shera was mentioned, I remembered that I was referenced in the
>>> footnotes of the original article in the QST - July 1998. It feels almost
>>> historical now. Brooks bought a few OCXOs from me.
>>> 
>>> I am currently working on a GPS stabilized OCXO.
>>> It is based on a Xilinx Zynq FPGA as the processor and counter arrangement.
>>> The hardware is starting to take shape. The control voltage of a 20 MHz OCXO
>>> is set by a DAC coupling from which I hope to set the voltage in very small
>>> steps.
>>> The OCXO has a CMOS level output which is converted to LVDS and is wired to
>>> the FPGA board. The Xilinx Zynq take a minimum frequency of 19 MHz as input
>>> to the PLL of the clock tile. My intention is to scale up the clock to some
>>> where a bit over 200 MHz to be fed to the counters.The 1 PPS from the GPS
>>> receiver is also fed into the FPGA to gate the counters.
>>> 
>>> The reason for my choice of processor is that I want to run Linux on it in
>>> order benefit from the large software base. Time distribution using PTPv2
>>> and a nice web-application to visualize and control what is going on inside
>>> is part of the intended concept.
>>> 
>>> I still have a long way to the finish line but I will try to present some
>>> results as I proceed.
>>> 
>>> I am following what is written on this list with great interest. It feels
>>> good to know that I am not the only nut ....
>>> 
>>> BR/
>>> Joakim
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>> 
>> 
>> 
>> -- 
>> 
>> Chris Albertson
>> Redondo Beach, California
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> 
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