[time-nuts] looking for low-power system for gps ntp timekeeping

[Mark C. Stephens]

At the risk of hijacking a thread, shooting of the subject and just generally bad etiquette for news group posting, I am running all my S1 NTP servers on HP thin clients!
They only draw ~14 watts of power.
I have managed to fit a 3.5 inch laptop drive in the T150's so they run a (minimal text based) full version of centos.

And the serial port seems to be okay:
NTP 1 running of a HP 58534A integrated timing antenna:
State	Remote		Refid	Stratum	Type		When	Poll	Reach	Delay	Offset	Jitter
o	127.127.20.0		GPS	0	Local clock	8	16	377	0.000	-0.001	0.002	

NTP2 running off an Acutime (hmm, marketing) Gold:
State	Remote		Refid	Stratum	Type		When	Poll	Reach	Delay	Offset	Jitter
*	127.127.29.0		GPS	0	Local clock	2	32	377	0.000	0.166	0.005	

I Don't know about Load handling, I farm most of the NTP requests off to a Stratum 2 (well technically S3 as GPS PPS is not true stratum 1, please correct me if I am wrong?)

But works well for me, I'd love to find a ref driver for the Z3805A port 2 even second string...
Perhaps using the parse driver w/ PPS refclock (is possible?)

Anyway, there is my 0.02c :p

-marki


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Iain Young
Sent: Tuesday, 2 July 2013 4:14 PM
To: time-nuts at febo.com
Subject: Re: [time-nuts] looking for low-power system for gps ntp timekeeping

On 02/07/13 06:43, NeonJohn wrote:

> Before anyone wastes his money on a BeagleBone, I suggest you join the 
> mailing list and read the hundreds of messages each day that pass 
> through, most of them citing problems, mostly with the Linux implementation.
>
> Basically, the ancient implementation of Angstrom Linux is a POS.  
> Just barely enough code to be able to say, for example, that SPI 
> works.  It does - sorta - but not well enough for any application 
> where clock timing or jitter matters.

You are not restricted to just Angstrom. My fleet run Debian. FreeBSD is also available. First thing I do is blow away Angstrom from any SD card.

> I had intended to embed the BB white in my next revision induction 
> heater.  After several months of frustration and a considerable amount 
> of money to a kernel programmer to write drivers that actually worked, 
> I gave up.  I could easily had a man-year in the application that I 
> can do bare metal in a few months.

Hmm, is this a case of Angstrom being beind the kernel curve, or is it still an issue when running things like Debian ? I've not had the need to use SPI on the BB yet, only the Pi.

> The thing that finally canned the BB for me was the short SD card life.
>   Even though the implementation uses a virtualized root file system, 
> it still writes to the SD card about once a second.  The result is 
> that even industrial grade SD cards rarely live over a year.  With the 
> Black they tried to address the problem by putting some NAND memory on 
> board but that only prolongs the problem and with components that are 
> not easily changed.

I've only ever had one SD card go dead on me on my entire fleet, and I suspect that was actually my fault, not Debian's :)

  > A final negative is the support.  The team member, a guy named Gerald,
> who provides official support on the mailing lists is one of the most 
> hateful persons I've encountered on the net. No, I never personally 
> had an encounter with him but I daily shook my head in amazement that 
> TI would let such a person rep them.
>

I've heard he can be somewhat robust to deal with. That said, he is very knowledgeable from what I've seen/understand. Never actually had to mail the mailing list itself though - found all the answers I needed in the archive - often from him!

> PS: Before you go to buy the Black, take a careful look at what all 
> they left off in an effort to compete with the Pi.

Hmm. I checked a lot of the things I'd need on the black for this type of application, and found they were all still there (Serial Ports, PRUSS, Timers etc). Yes you may need to twiddle the pinmux as by default it goes to  he HDMI stuff etc, but they are still there

Is there something specific here you are thinking of ? Maybe I just don't need what they left off. I do remember looking and going "Meh, not important for what I'm doing"


Best Regards

Iain


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