lightmeter.py is a pure-python for the lightmeter. It is supposed to
spit out skyglow http://www.darksky.org/NSBM/sdf1.0.pdf, modelled after
http://www.darksky.org/NSBM/example_iyal_file.txt.

To install, run

sudo make install

This will install the program into /usr/local/bin.

It will also install a classical init script in /etc/init.d.  On
Debian-derived systems, it will also set the necessary links using
update-rc.d; on other systems, you'll have to run the equivalent of

	ln -s /etc/init.d/lightmeter /etc/rc2.d/S70lightmeter

(or whatever) yourself.  If you run systemd, would you contribute the
appropriate incantation?

You will probably want to add a system user that the driver will change to
when it is started as root (this happens, e.g., when the thing is started
from the init script):

	sudo adduser lightmeter

(if you don't like that name or would like to run the thing as an existing
user, you'll have to change the LM_USER in the initscript, too).  To run
the lightmeter, you should generally change to this user, e.g., via

  sudo -u lightmeter bash

or an equivalent command.


Finally, to let normal users access the the device, you need to add a
udev rule; the following will probably work:

	sudo tee /etc/udev/rules.d/10-lightmeter.rules <<EOF
	ATTR{idProduct}=="fcb7", ATTR{idVendor}=="04d8", SUBSYSTEM=="usb", MODE:="0666"
	EOF

If you had the device plugged in already, you'll need to replug it after this.


Configuration file
==================

To run this, you'll want a configuration file .mlumrc in the lightmeter user's
home (that'll be /home/lightmeter/.mlumrc with the standard init script).

Here's a commented template to get you started (it's the built-in default):

[general]
# The station id (mandatory!)
stationid =
# The station access key (mandatory!)
accesskey =
# latitude of the station, in decimal degrees (southern latitudes have
# a minus sign; mandatory!)
latitude = unconfigured
# longitude of the station east of Greenwich, in decimal degrees
# (i.e., eastern longitudes are positive, western negative; mandatory!)
longitude = unconfigured
# elevation of the station (in meters; manatory!)
elevation = unconfigured
# IANA timezone name of your *local* time zone; take a string from
# http://en.wikipedia.org/wiki/List_of_tz_database_time_zones
# (and make sure your computer is actually configured to use that
# time zone; mandatory)
timezone = unconfigured

# sample interval, in seconds
sampleInterval = 2
# upload interval, in hours
uploadInterval = 24
# root directory for data
rootDir = ~/lightmeter-data
# The base URL of the upload service
uploadbase = http://dc.zah.uni-heidelberg.de/lightmeter/q/upload/custom
# The type of the device; this is always IYA Lightmeter possibly with a
# version (in case you know, it'd look like "(Mark 2.3)")
deviceType = IYA Lightmeter
# some real name, possibly affiliation (like B. Honeydew, Muppet Labs)
operatorName: a/a
# Some verbose location description, like "Roof of the Muppet Theatre,
# Broadway, New York, USA)
locationName: n/a
# How does your computer get its time?  This could be something like
# NTP, GPS, monthly by hand; choose whatever conveys your practice to
# the users of your data.
syncMethod: n/a
# change this if your device doesn't look straight up.  North Horizon
# is 90,0, east horizon is 90, 90
pointing: 0,0

# The four calibration parameters.  What's given here is
# generic values that may make for bizarre results.  To have your
# data calibrated, contact GAVO.
calibA: 150000
calibB: 0.01
calibC: 2e-9
calibD: 0.004
# Change this to true once you have an actual calibration for your device.
calibrated: False

# The port the built-in HTTP server is listening on
httpPort: 1082
# A (valid) system user to run as when started as root
user:lightmeter


[TODO: run-as,...]