Internal pressure sensor

Stroller stroller at
Thu Oct 1 16:57:18 CEST 2009

On 30 Sep 2009, at 22:18, Christoph Mair wrote:
> ...
> I successfully added a pressure sensor to my Freerunner. The BMP085  
> chip from
> Bosch Sensortec is a small (5x5x1.5mm) chip which includes a  
> pressure and a
> temperature sensor. Power and I2C is enough to get it working. I  
> glued it next
> to the BT antenna. The wiki page contains some pictures:
> Sourcecode is available from
> board/bmp085

Cool! How accurate do you find it?

This makes the Freerunner a nice mobile for glider / hang-glider /  
paraglider pilots. They most always carry a varioaltimeter with them,  
and last time I flew (some years ago) GPS was beginning to have a  
significant impact upon that (niche) market. The combination of  
barometric pressure with groundspeed allows one to easily find the  
optimal speed-to-fly, allowing for head- or tail-wind on a glide  
between lift sources (thermals).

I'm sure that this sensor must be at least as accurate as those used  
in the cheap commercial ($250) varioaltimeters of 10 years ago, so it  
looks really good for this sport, if someone has the time to make a  
nice interface.

It would be interesting (for me, anyway) to test by climbing a small  
hill and see if the pressure difference is reflected accurately. 30m  
should be a good initial test.


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