Raspberry Pi HOWTO progress

[Eric S. Raymond]

Unless called out here I just merged your changes,

Gary E. Miller <gem at rellim.com>:
> Don't do it!  How long did it take to get you to solder???

Once I decided to learn it, all of about 15 minutes from a cold start.
My instructor allows how I got *good* at it quickly, too; I thank my
Swiss-German clockmaker ancestors :-)

> > The Adafruit HAT is shipped as two parts, a circuit board and a 40-pin
> > header.
> 
> Don't do it!  You can buy similar already assembled.

Source?

> >  Your first step will be to solder the header to the bottom of
> > the board, on the opposite side from the GPS module (under what would
> > be the east edge if the Adafruit logo were a map legend). Poke the
> > header pins upwards through the double row of through holes at the
> > east edge of the board and go.
> 
> This can easily lead to disaster for the newbie.  The alignment is
> critical.  It is too eassy for a newbie to tilt the pins so they will
> not insert into the RasPi.  Better to insert the pins in the RasPi
> connector, the place the HAT on the other end of the pins, then solder.
>  
> > The header on the assembled HAT fits down over the
> > double row of pins on the east edge of the Pi, such that the two
> > boards make a neat stack.
> 
> Swap, do this first, then solder.

New parts:

* (Optional) 2 hex standoffs, .625" with 440 threading, 2 compatible
  nuts, 2 compatible screws.  These are the standard spacers
  used in PC cases; if you keep the small parts from old PCs around
  you'll have a dozen of them.

New instructions:

   First: mate the female side of the detached 40-pin header with the
   40-pin GPIO connector on the SBC (this would be the east edge if the
   Adafruit logo were a map legend).

   Second: if you have them, bolt the the two hex standoffs to the corner
   holes on the opposite (west) side of the SBC, female end up.  These will
   support the HAT while you're soldering it to its header.

   Third: Lay the HAT over the board in such a way that the two sets
   of 4 corner holes line up and the header pins poke through a
   matching 40 holes in the HAT.  The GPS module and battery clip
   should face upwards. If you added standoffs, they should match the
   corner holes of the HAT.

   Fourth: Solder each header pin into its through-hole. This is the last
   bit of hardware hacking absolutely required.

   Fifth: If you added standoffs, now secure the HAT to their
   female-threaded upper ends using the screws.  This will help
   protect the headers and pins from mechanical stress if the
   assembly is dropped or has something sat on it.

> > (The device is shipped as parts almost certainly to evade a regulatory
> > requirement for FCC conformance testing to RF emission standards,
> > which is expensive and would have added to the unit cost.)
> 
> Irrelevant.  Probably wrong.

You can argue this with Phil at Penguicon.

> > Next, check to see if you can expand the filesystem on the SD card;
> > the option may be active or frozen depending on how your SD card was
> > made.
> 
> How to expand?

There's an option for it in both configurators.
 
> > ------------------------------------------------------------------------
> > # arp -a
> > ------------------------------------------------------------------------
> > 
> > run from any machine on your network, will give you a list of
> > IP-addresses/hostnames that are or have been active on your network
> > (the information is cached).
> 
> Gack, this  only works AFTER you have pinged the pi!  It will not help
> you find the pi.

I just shut down the Pi, booted it, and arp -a found the address before
I pinged it.
 
> > To disable the serial console, remove all "console" options.
> 
> And the result looks like?  I prefer to cut/paste your result, not to have
> to hunt/peck.

Added.
 
> > the north end of the connector. Most other GPIO pins can be
>       ^^^^^ North???

I explained this earlier. Orient as though the Adafruitlogo were
a map legend.
 
> > In all versions, you force the driver to be loaded by
> > editing /etc/modules to contain the line "pps-gpio".
> 
> Or compile it in the kernel, like a real man would do.

We're trying to keep things simple, here.
 
> > When the red LED on the HAT blinks once per second, you don't have a
> > satellite fix. When it achieves lock it will blink with much lower
> > frequency.
> 
> Nice to know BEFORE the ppstest, if PPS is gated on a good sat lock.

Good point.  Moved.

> > ------------------------------------------------------------------------
> > KERNEL=="ttyAMA0", SYMLINK+="gps0"  
> > KERNEL=="pps0", OWNER="root", GROUP="tty", MODE="0660",
> > SYMLINK+="gpspps0"
> > ------------------------------------------------------------------------
> 
> Sorta defeats the ttyAMA0 -> pps0 autodetect??

No, it still work. Those aliases are for NTP/NTPsec.

 
> > # Internet time servers for sanity
> > server 0.pool.ntp.org iburst prefer  
>                                ^^^^^^  huh???

Got me.  I don't know what that does either.  It's from <<NEVILL>>.  
It'd be nice to add an explanation.  Perhaps Hal knows.

> > The text "mode 17" tells it to look for $GPRMC messages at a baud of
> > 9600bps.
> 
> Except your earlier test was at 4800!

$ stty -F /dev/ttyAMA0 raw 9600 cs8 clocal -cstopb

> > Internet time servers for sanity::
> >    This section specifies some NTP pool servers to act as a sanity
> >    check for our GPS time. They will also keep the time accurate if
> >    your GPS loses signal.
> 
> Ho about using the us pool?  Or local country pool??

Config file was witten by a Brit.
 
> Talk about 'ntpq -p'.

Suggested wording welcome.  I've barely ever used it.

> Or do: # dmesg | tail

I'd prefer not to.  dmesg tends to be a firehose, and cryptic to boot.
 -- 
		<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
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