BMP180 and Raspberry Pi

Update: I found this gave incorrect readings, see this post for the method I used to correct problems with height measurements.

The I2C pins on my Raspberry Pi for the Weather Ballon project were tied up with a Real Time Clock. However, this stopped working after a week and so I decided to add the BMP 180 atmospheric pressure sensor. This would not only give the pressure but would provide an air temperature reading that the onboard thermometer in the radio could be compared against. There does not seem to be too much information on the Internet about using this sensor on the Pi and using Python, so I went over to the Adafruit site and followed their instructions.

I added the the library but as soon as I tried to run the script in IDLE it showed an error. When I tried the Adafruit example it worked perfectly as long as I ran the script directly. If I loaded into IDLE and tried to run it would not work. So, I made the alterations to my weather balloon script and saved the file. I shut down VNC and opened up connection via SSH. I use Serverauditor on my iPad, and once it was running I used the following commands:

Cd /home/pi/Weather_Balloon

Sudo Python

Once the programme was running I could monitor the output from the slave on my iPad.

I made some alterations to the main control panel software running on my laptop and now the local pressure, sea level pressure and height (measured on the balloon) are shown. I am hoping to be able to show how pressure decreases with height above sea level.


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