Arduino with BMP085 barometric pressure and temperature sensor

This post is part of a series on Arduino-based energy and climate monitoring.

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The BMP085 is a barometric pressure and temperature sensor that connects over i2c to a Arduino pro mini (3.3V) with a RFM12b transceiver. The barometric pressure will be the same everywhere in and around the house, but the -40 to +85°C operational range makes this sensor specifically suited for outdoor use.

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Power is provided by connecting a rechargeable 18650 LiPo battery to VCC on the programming header of the Arduino. This battery provides nominally 3.7V, which in my experience is close enough for the board to work fine.

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The Arduino, battery and sensor are packaged in a zip-lock bag to keep moisture out and are lying in a shady spot on the balcony. It performs a temperature and pressure reading every 64 seconds and transmits it to the central relay module. Between recordings it falls asleep to save power.

You can find the sketch for the Arduino here.