I am looking for a digital pressure sensor (for measuring alitude). I have seen Freescale's extensive line of pressure sensors but they have an analog out, which is not very accurate. Is there some kind of pressure sensor with digital communication like i2c or something? Thanks!

 

What is the range in pressure that you need to measure?

hgmjr

 

I would like sea level (101.33 kPa or 760mm Hg) to about 1000 feet (97.63 kPa or 746.3mm Hg). Accuracy is important, doing some calculations with the analog-out sensors the accuracy is like +- 100ft which is too much.

 

One thing to keep in mind, to measure altitude with a pressure sensor requires it to be of a absolute pressure type/model, not a gage or differential pressure type/model. I've seen several people order the wrong type for this application. Also if accuracy is important remember that you need to factor in the local barometric pressure variation as the standard/fixed altitude Vs absolute pressure formulas typically assume standard temperature/pressure conditions which is not the case in real life use. I used a aircraft VHF band radio to pick up broadcasts from local air fields as their station ID gives continuous local temp and barometric pressure.

I found the analog output accuracy to be good enough for this kind of application as other physical variables will most likely swamp the results.

Lefty

 

Helo,

Freescale seems to have a digital pressure sensor with i2c connection:
http://www.earthtimes.org/articles/show/freescale-digital-pressure-sensor-enables,844992.shtml

Greetings,
Bertus