surface. Like the altimeter setting, it is a “reduced” pressure, which

uses observed conditions rather than “standard” conditions to

remove the effects of elevation from pressure readings.

The calculation to get from Pascals to ‘Altimeter setting’ is a bit gnarly:

Formula to convert Pascal pressure to Altimeter setting

Grab the full formula here and give this great Altimeter setting calculator a

try. This formula relies on two things: knowing the current pressure in

milibars and knowing the height above sea level that the pressure was

read. We recommend you capture altitude using a local survey point or a

GPS receiver.

If you installed the MPL3115A2 library, you should also have the

BarometricHgInch example sketch under the

Examples->MPL3115A2_Pressure menu under the Arduino IDE. We didn’t

build this calculation into the library because it could potentially chew up a

lot of RAM and code space calculating all the floating point math. But, if

you’re doing home weather station calculations, this should get you started.

Resources and Going Further

Now that you’ve got barometric pressure sensing under your belt, consider

checking out the following projects and products:

• MPL3115A2 Datasheet

• MPL3115A2 Breakout Schematic

• Combining with an Electric Imp to create a wireless pressure sensor

• Combining multiple pressure sensors to create a tactile robotic hand.

Also see TakkTile.

• Checkout the Weather Shield for the MPL3115A2 combined with

many other sensors

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2/12/2015

https://learn.sparkfun.com/tutorials/mpl3115a2-pressure-sensor-hookup-guide?_ga=1.47223329.725293211....