Netduino Weather Board with Humidity and Barometric Pressure

Had a few modules kicking around that I ordered on a whim a while back. Figured it’d be worth making something interesting out of them as an excuse to learn a little more about i2c. Slapped together this board with a couple of sensor breakouts on it and stuck it on the back of a Netduino Plus. I like the netduino boards because they’re hardware compatible with the arduino shields, but being able work in C# makes them a little more familiar. The sensors are a Bosch BMP085 barometric pressure sensor and a HTU21D. The HTU21D is on a Sparkfun breakout board, the BMP085 is a 3$ ebay dealie. Forgive the ugly solder job.


The idea is to stick this board in various locations around the house and see how the temperature and humidity vary throughout the day. Want to get an idea of just how dry it gets in this place during the winter and how well the furnace pushes the warm air around. This board will quietly log all of these items in a csv file on the SD card installed in the Netduino.

It took a fair bit of monkeying around but I managed to get two fairly useful classes for reading from both of these sensors. The I2C methods came from the library referenced in this post. The logic for the BMP085 sensor was modified from this Arduino specific tutorial to create the Netduino version.

I’ve posted the source in a github at for anyone that might be able to make use of it. The code might not be pretty but it might help if you’re trying to deal with either of these two sensor modules on the Netduino platform.

The data logs pretty well, the only thing I might need now is a real time clock module though because right now all I can record is the relative time from the board booting and beginning to log.

Temp Sensor1 23.05 Relative Humidity 29.3546143 Barometric Pressure 97889 Altitude(m) 290.07
Temp Sensor1 23.20 Relative Humidity 28.5993042 Barometric Pressure 97891 Altitude(m) 289.90
Temp Sensor1 23.14 Relative Humidity 27.9889526 Barometric Pressure 97897 Altitude(m) 289.38

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4 responses to “Netduino Weather Board with Humidity and Barometric Pressure”

  1. Tobias Vandenbempt says :

    Care to share some code you used as well? I’m stuck getting readings from the BMP085. If you have the time to take a look ?

    My blogpost
    Netduino Forums Post

  2. rhasbury says :

    Sure. It’s up at this github post:

    I thought I posted it there when I made the blog post but I guess I neglected to hit publish in the github client. Let me know if you have trouble getting to it.

    I’ll head on over to the netduino forum thread you’ve got started and respond if I can see anything I can contribute.

  3. Börje Johansson says :

    Really great example, I am just looking at the HTU21D (humidity sensor) an your CBus class helped me wireing it all up.

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