[time-nuts] inexpensive, black box, GPS or NTP based TTL time capture?

Nick Sayer nsayer at kfu.com
Tue Oct 24 20:04:01 EDT 2017


FWIW, I’ve documented the whole R-Pi GPS NTP thing at https://hackaday.io/project/15137

As a disclaimer I will also say that I’m not even remotely the first. But what’s kind of nice is that I have a R-Pi desk clock display board that plays really well with a bolt-on GPS cap. In fact, I’ve got two of them in the NTP pool right now.

Sent from my iPhone

> On Oct 21, 2017, at 7:50 AM, ROY PHILLIPS <phill.r1 at btinternet.com> wrote:
> 
> 
> ----Original message----
> From : hmurray at megapathdsl.net
> Date : 21/10/2017 - 7:49 am (GMTDT)
> To : gem at rellim.com
> Cc : time-nuts at febo.com, hmurray at megapathdsl.net
> Subject : Re: [time-nuts] inexpensive, black box, GPS or NTP based TTL time capture?
> 
>>>> For under a $100 you could get a Raspberry Pi, a GPS HAT, and
>>>> connect your input to a GPIO pin.  Configure ntpd to log the real
>>>> PPS and the input as another 'PPS'.
> 
>>> Is there an option to log all individual PPS events?
> 
>>   # ppswatch /dev/pps0
> 
> That's a way to log stuff, but I don't think it comes under "Configure ntpd".
> 
> I remember some option to log lots of stuff, but I don't remember the 
> details.  It could have been in a driver.  I couldn't find it in the man page 
> for the PPS driver.
> 
> [amazon]
>> Looks like $96 to me.  You can save some if you buy in bulk,
> 
> You can save $7 if you get the starter package that has only Pi, SD card, 
> power, and case.  (Many starter packages include stuff you probably don't 
> need and that raises the price.  But maybe one has a HDMI adapter.  I didn't 
> look.)
> 
> Beware of using normal USB cables and/or normal USB power supplies.  The Pi 
> is not happy with low voltage.  The drop in a USB cable can be significant.  
> The setups intended for use with Pis normally have 5.1 or 5.25 volts and 
> heavier gage wire in the cable.
> 
> 
> [display, kbd, mouse...]
>> Yeah, just for setup.  Shall we include the price of the desk it sits and
>> the building it is in?
> 
> I'm willing to assume somebody has a table and a roof.
> 
> The display and such are not a problem if you have a PC you can borrow them 
> from.  (You probably need a HDMI adapter.)  But that doesn't work if all you 
> have is a laptop or smart phone.
> 
> I think most of my friends have PCs but I wouldn't be surprised if some of 
> them had a laptop and no PC.
> 
> If your PC is old enough, the keyboard and mouse may be PS2 rather than USB.
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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