domingo, 15 de março de 2009

An ethernet weather station

Usando um ‘add-on’ para o já existente servidor AVR Ethernet, vamos construir uma estação meteorológica. Isto é: Uma estação meteorológica com um servidor Web integrado. Os artigos relacionados que descrevem como construir o servidor Web AVR estão aqui:
  1. An AVR microcontroller based Ethernet device
  2. HTTP/TCP with an atmega88 microcontroller (AVR web server)
Os componentes para a construção desta estação meteorológica podem ser encomendados a partir de http://shop.tuxgraphics.org/·
O sistema é modular. Você pode construir uma estação meteorológica Ethenet pura ou uma estação meteorológica Ethenet com um display LCD adicional.

Ver: http://tuxgraphics.org/electronics/200704/article07041.shtml

Sensors

My original plan was to have sensors for temperature, air pressure and wind. I started a prototype and it worked very well except for the wind measurement part. I have written a separate article about it: wind-vane-ver01.shtml. I plan to improve the wind measurement hardware and add it at a later point in time.

For now the weather station has 2 temperature sensors and an air pressure sensor. It works reliable and precise even after several month of testing.

For the sensors we will use:
  • For temperature measurements: LM335. This sensor is cheap and has a linear curve over a wide temperature range. This will give us very accurate temperature readings over a wide range. The accuracy will be almost constant over the whole range.

  • A Motorola/Freescale MPX4115A absolute air pressure sensor. This sensor is already calibrated at production time. The MPX4115A is not made for out-door use but that is not a problem. The circuit can be in a save and dry location inside the house as the air pressure is exactly the same inside and outside the house.

The weather station circuit diagram (add-on board)

 [weather station circuit with LCD, top view]

0 comentários:

 
View My Stats