== Data Logger

This is a fairly basic app designed to read data from a variety of
sensors over a serial port, store them in a PostgreSQL database, and
display them on the web.

The data comes from Arduino units.  The source code for that is in the
arduino directory.

Eventually it will support downloading data that has been logged in
the past.  Currently it assumes all data is freshly generated
(i.e. sensor was read just before transmission).

== Sensors

Right now, the only two sensors supported are a temperature sensor
(i.e. DS18B20 one-wire device) and a timing sensor - just counting
seconds between pin transitions.

The temperature sensors have been used extensively for several months.