[time-nuts] Frequency counter recommendation

jimlux jimlux at earthlink.net
Sun Dec 19 15:35:39 UTC 2010


Gerhard Hoffmann wrote:
> Am 19.12.2010 05:52, schrieb Bob Camp:
> 
>>  The real thing you would learn about is writing code that runs an FPGA.
> 
> Yes. A good starting point would be a Xilinx SP605 kit.
> It's about the $750 for a decent 5370 and includes
> many points from Bobs option list.
>> The other gotcha here is that the feature list can get pretty large:
>>
>>
>> 3) USB 2.0 interface
>> 4) RS-232 interface
>> 5) HPIB emulation of an HP box    (w/o drivers)
>> 6) Ethernet interface
>> 1) Web server software
>> 1) Front pannel controls       (W/o mechanic)
>> 2) Front pannel display        (VGA output)
>> 3) Front interface connections (DUT's)
>> 4) Rear pannel standard interfaces and controls  (w/o mechanics)
>> 2) Flash card storage
>> 3) USB stick storage
>> 4) SD card storage
>> 5) Battery backed RAM storage
>> 1) Some number of counter inputs ( some programmable SMA I/O)
>> 2) Some number of reference inputs
>>
>> 1) Battery power
>> 2) Auto 12 V power
>> 3) AC line power
> use as a PCIE card in a pc or mac


I hate cards that plug into a PC.  The PC bus respin cycle is much too 
short, and you have device drivers, etc. to worry about.  At work, we 
use rack mounted PCs to control a bunch of test equipment.  Since we're 
doing spacecraft stuff, the "design use life" of the rack is 2-3 years, 
but it will be used beyond that, and often, will get reused for the next 
project.

I've spent way too many hours hunting for another ISA bus machine, or 
trying to resurrect NT4.0, because there's no device drivers for 
anything newer.

In my book, RS232 is fine for low end, Ethernet is even better, USB 
looks pretty good and has some staying power.  Folks implementing things 
on USB tend to use simple conceptual models (e.g. emulated serial port).

My only gripe about USB is that it's a very master/slave sort of thing.





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