Change in Barometer Chip

For the 2012 series board I used a barometer chip that I got from Hope RF in China.IMG_1356  The device is reasonably cheap, precise and stable but is a bit shy.   What I mean by this is that the sensor is not only sensitive to pressure, but also to light.  When I initially tested out the stations I noticed that the pressure always was higher by a few millibar during the day compared to the night.  Not exactly what you hope for in a barometer.  Since it also requires a local clock oscillator for operation the cost benefit was not not there and I decided to change over to a different device.

I choose the BOSCH BMP085 device which I previously used in a wireless sensor network. DSC01439_croppedUnlike the Hope-RF device it has a tiny aperture for the pressure to enter, is not sensitive to light, has a 16 bit Thermometer and doesn’t need a high precision, jitter free clock to operate.  Having done the code that reads the device and  applies the built in calibrations values it was a half days of work to port it over to the weather station system.

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