Re: [gpsd-dev] Draft Stratum 1 Microserver HOWTO is up

[Clark B. Wierda]

I just finished a pass using a GR-601W and adjusting as needed.  I will only address the items that still apply and that are not already mentioned by Hal.

On Sat, May 21, 2016 at 12:03 AM, Hal Murray <address@hidden> wrote:

> A micro-SD card. 1GB is minimal. 4GB is plenty.

I decided 4 GB wasn't big enough, but I build gpsd, NTPsec, and NTP classic,
and keep lots of log files.  It felt like builds were slowing down, but maybe
I was just getting impatient.  I don't have hard numbers.  I think SD cards
work better if they are not close to full.

The Rasbian-lite image is 1.3 GB.  My 1 GB microSD failed before it ran out of space, so I was not able to test this explicitly.

Also, after finishing the process, the space used was 1.3 GB.  I started with a fresh install and only did the builds mentioned in the manual steps.

 

You describe assembling the board and HAT before inserting it into the case.
Have you tried that?  I don't think it will work.  The board has to go in
tilted, HMDI side first.  The HAT gets in the way of the tilt.

You might mention the DogBone case.

GeauxRobot Dogbone Case for RPi 3 (and others) 

 

> device will likely be /dev/sdd

Mine works out to be sdd, but I think that depends on several things.  I have
a second hard disk that gets sdb, and I use a multi-slot USB to small-card
adapter that sets up sdc, sdd, sde, and sdf.  The SD slot just happens to be
sdd.

It was /dev/mmcblk0 using the built-in card reader on my laptop.

 

> There is a different, non-HAT Adafruit product, the "Ultimate GPS Breakout
> Board", that also uses GPIO18/P1-12. This may be a source of confusion if
> you read some of the references in this document.

The breakout board doesn't know anything about GPIO pins.  You are probably
thinking of some writeup that cloned the Uputronics pins.

There is a write-up on the Adafruit site that wires the PPS to GPIO18.

 

> # Known Stratum 1 servers with excellent quality and connectivity.
> server 199.102.46.72 iburst     # tock.usshc.com
> server 149.20.64.28 iburst      # clock.isc.org
> server 17.254.0.49 iburst       # tick.apple.com

This gets complicated.  It's also important.

In general, you don't want to wire a name or address into gear that you don't
directly control without the owner's permission.  If you do get their
permission, you want to set things up so that they can easily and cleanly
revoke that permission.  This holds for things like anti-spam black lists as
well as NTP servers.

One way to revoke permission is to insert a layer of indirection in the DNS,
a cname.  Deleting that cname (or the landing name) breaks things and stops
the traffic.  (It may shift the load to the DNS servers.)

The wikipedia page on NTP abuse is very good.
  https://en.wikipedia.org/wiki/NTP_server_misuse_and_abuse
I think Dave Plonka's writeup should be required reading for any computer
science degree.

On top of all that, the connectivity is only good if you are located near the
servers.

We may want to just use the NTP Pool (and get a vendor code which addresses issue Hal mentions).  That should be good enough for sanity checking.

Something like:

server 0.ntpsec.pool.ntp.org

server 1.ntpsec.pool.ntp.org

server 2.ntpsec.pool.ntp.org (this one will also support IPv6)

We could also mention that the ntpsec could be replaced with their region (us, europe, ...).

 

> GPS Serial data reference (NTP0) [Second one]
  NTP0 => NTP1

> Internet time servers

There is no section of the ntp.conf labeled "Internet time servers"

Your ntp.conf doesn't enable any logging.


> # ntpsec/build/main/ntpq/ntpq -p

The printout doesn't match the ntp.conf you just described.  It's still using
4 pool servers.

> # cp pinup /usr/local/bin
What's "pinup"?  Where did it come from?

'pinup' is downloaded by the automated script.  Also, in that script, it is expected to be in the directory above the 'ntpsec' directory with 'ntp.conf' which doesn't quite match the manual instructions.

I stopped after copying the text into the correct files and rebooting.

 

> Odroid C2

I'll test this one after verifying the Adafruit HAT against the RPi2 and the RPi3.

Clark