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Welcome to the office-weather wiki!

This project is Arduino and Python/Twisted code to implement a simplest-
possible ‘office weather station’ that presents temperature and relative
humidity readings via a webserver interface.

The sensors are:

• LM35CAZ Nice, TO-92 cased, temperature sensor with 0-5VDC output and no
  external components required. A few bucks from National.
  http://www.national.com/mpf/LM/LM35.html#Overview
• Ohmic Instruments SC-600 humidity sensor and signal conditioning module.
  http://www.ohmicinstruments.com/pdf/SC-600.pdf
  About $15, quite cheap for a sensor this nice. You need an external RC
  lowpass, so two more components in the circuit. See the PDF.

Software:

• The Arduino sketch simply sends the two ADC counts, as integers, on
  a single text line once per second, nothing else.
• The Python code, implemented as a Twisted app, uses their LineReceiver
  class to get notifications of each new line, after which it does the
  parsing, linearization and units. Overkill but simple.

The twisted code also adds a simplest-possible HTTP interface, running on port 2000. The format used is designed for ingestion into Cacti, for nice time-based RRD graphs.

Notes:

• The Mac Mini I’m using to host this has to have the Arduino drivers in
  place to use the virtual serial port for communications.
• I’m debating an ethernet shield, but $50 seems overpriced for now.