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

[Gary E. Miller]

Yo Eric!

On Fri, 20 May 2016 10:10:54 -0400 (EDT)
address@hidden (Eric S. Raymond) wrote:

> I now have, at
> 
> http://www.catb.org/esr/faqs/stratum-1-microserver-howto/

Great progress, but...

It could use some photos, got a smart phone with camera?

My comments are in the same order as the howto, so you can go linear.

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"a HAT uses an internal RS-232 interface "

±5v to ±15V?  I think not, and not so 'internal'.  I'd say:

"a HAT uses an direct serial interface "

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Typo:

"Uputronics board snugs ino an on-board fitting and"

ino -> into

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"A bit of work with a dremel will fix that. "

Dremel(tm)

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"Note: your host may automount the card if it has been set up for Linux before. 
You should unmount it."

Uh, how?

I use "dmesg | tail" to check, you don't like that.  Do we tell the user about
df or mount?

I know Ubunut does automount, and it does so in a weird and barely predictable
manner.

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". On a host running Debian or Ubuntu, the device will likely be /dev/sdd and 
your command will look something like:"

Whoa Nelly! telling the user to dd to a device they have not triple
checked is the right one!  Gack.

----

"# ddimage sdd"

For upard compatibilty, maybe change the script to take the image file name?
Maybe even do the unzip to?

So, instead of:

# unzip 2016-03-18-raspbian-jessie-lite.zip
# ddimage sdd

Just:

# ddimage sdd 2016-03-18-raspbian-jessie-lite.zip

ddimage could unzip to stdout and save some disk space:

unzip -c 2016-03-18-raspbian-jessie-lite.zip | ddfldd bs=4M  of=/dev/sdd

I would copnsider adding "sync" to the end of the script so it does
not complete before the iamge is fully on the sd card.  otherwise
the user might remove the card after the script completes, but before
the card is fully written.

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"Make sure your Pi has a live Ethernet cable plugged in and "

The network leds should flash.  Then try the ssh...

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Typo in the clockmaker script:

# that the --nstall mode will install.
           ^^^^

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"These changes are not reversible, but you’d want them for any other
use of the SBC anyway."

How about:

"These changes are not reversible, but you always want to be updated
with security and other updates."

----

" but not before installing some packages need for the next step."

need -> needed

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Table 1. Blink interval in seconds

Same blink SKU 424254 for fix and not fix???

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"take 20-30 minutes to download a satellite ephemeris. "

ephemeris -> almanac

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"You should see NMEA0183 sentences issuing in bursts once per second"

example?

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"server 127.127.28.0
fudge 127.127.28.0 refid GPS"

maybe start with a 420 mS fudge?

So:

server 127.127.28.0
fudge 127.127.28.0 time1 0.420 refid GPS

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"Turn off the default ntpd service running on your SBC"

Maybe just uninstall the POS?

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Gack, you forgopt the -n!!!

# gpsd/gpsd /dev/gpsd0

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"Install the pinup script:"

Uh, I don't have that??

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" If you decide to ditch systemd you can mame a link"

mame a link?  Ouch!

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"and use ntpq -p to verify that you can see time samples coming in."

How about "watch ntpq -p" ?

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"On the SBC, create an account for "me" (whatever username you like)
using adduser run as root."

I have seen windows hosts hacked in minutes after going live.  Do this
WAY earlier in the process.

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Duplication!

"You will probably want to re-fetch clockmaker and do a "clockmaker --build" in 
your home directory."

Another reason to add the new account early.

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"Don’t be overly concerned if ntpq -p initially shows large jitter. "

Examples of good and bad?

---;


"The resulting configuration is pretty minimal, as you can verify by running 
"ps ax" 

I find perple get "pstree -paul" a lot quicker.

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"The important thing to check is whether the pps-gpio driver triggers on
leading or trailing edge."


Uh, no.  Always the leading edge, but is the leading edge the assert
(rising) or clear (falling) edge?

leading -> assert (rising)
trailing -> falling

The adafruit HAT has the leading edge on the assert edge.
Other GPS can have the leading edge on the falling edge...

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" as your Odroid will be running a stock Ubuntu rather than Raspbian. "

Mostly stock Ubuntu.  I found that out the hard way.  It is a custom
kernel.

---

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

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