Freescale MPL115A2 Pressure

[copterrichie]

Question, just how accurate is ±1 kPa Accuracy in terms of actual altitude measuments?

http://cache.freescale.com/files/sensors/doc/data_sheet/MPL115A2.pdf

Miniature I2C Digital Barometer

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The MPL115A2 is an absolute pressure sensor with a digital I2C output targeting low cost applications. A miniature 5 by 3 by 1.2 mm LGA package is ideally suited for the space constrained requirements of portable electronic devices. Low current consumptions of 5 A during Active mode and 1 A during Shutdown (Sleep) mode are essential when focusing on low-power applications. The wide operating temperature range spans from -40°C to +105°C to fit demanding environmental conditions. The MPL115A2 employs a MEMS pressure sensor with a conditioning IC to provide accurate pressure measurements from 50 to 115 kPa. An integrated ADC converts pressure and temperature sensor readings to digitized outputs via a I2C port. Factory calibration data is stored internally in an on-board ROM. 

Utilizing the raw sensor output and calibration data, the host microcontroller executes a compensation algorithm to render Compensated Absolute Pressure with ±1 kPa accuracy. The MPL115A2 pressure sensor’s small form factor, low power capability, precision, and digital output optimize it for barometric measurement 
applications.

Features
• Digitized pressure and temperature information together with programmed
calibration coefficients for host micro use.
• Factory Calibrated
• 50 kPa to 115 kPa Absolute Pressure
• ±1 kPa Accuracy
• 2.375V to 5.5V Supply
• Integrated ADC
• I2C Interface (operates up to 400 kHz)
• 7 bit I2C address = 0x60
• Monotonic Pressure and Temperature Data Outputs
• Surface Mount RoHS Compliant Package

[Hamburger]

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Low current consumptions of 5 A during Active mode and 1 A during Shutdown (Sleep) mode are essential when focusing on low-power applications

not really low current consumption, is it? Was meant to read mA or uA?

Question, just how accurate is ±1 kPa Accuracy in terms of actual altitude measuments?

1 hPa <=> 1 mbar, so 1kPA <=> 10 mbar. Does that help?

[copterrichie]

1 hPa <=> 1 mbar, so 1kPA <=> 10 mbar. Does that help?

Pressure altitude divided by 100 feet (30m) as the flight level, and is used above the transition altitude (18,000 feet (5,500 m) in the US, but may be as low as 3,000 feet (910 m) in other jurisdictions); so when the altimeter reads 18,000 ft on the standard pressure setting the aircraft is said to be at "Flight level 180". When flying at a Flight Level, the altimeter is always set to standard pressure (29.92 inHg / 1013.25 mbar).
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Pressure altitude is the elevation above a standard datum air-pressure plane (typically, 1013.25 millibars or 29.92" Hg). Pressure altitude and indicated altitude are the same when the altimeter is set to 29.92" Hg or 1013.25 millibars.

http://en.wikipedia.org/wiki/Altitude

So is that Good or Bad?

[Hamburger]

approximately 100 hectopascals per 800 meters

from wikipedia again (altimeter).
100 hPa = 10 kPa, so
+-1 kPa would then equal +-80 meters. Would have to compare this with the sensors we usually use...
Min you, it is the accuracy of the absolute altitude. This does not automatically say how accurate it would be between two measurements (like copter on ground and copter in the air). That value could follow a different accuracy altogether.

We are not usually interested in our exact absolut altitude, are we? More often it would be about the height relative to starting position or height 5 sconds ago, I think.

The alt.hold guys would know more about this.

[copterrichie]

Thank you, there is just so much going on with this project and the topic of Barometer and now they work is something I had not ventured into until now.