Barometric pressure readings are inconsistent. MPL115A1

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Barometric pressure readings are inconsistent. MPL115A1

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Contributor I

Why am I seeing the barometric readings fluctuate when accessing the barometric pressure registers of the MPL115A1?

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NXP TechSupport
NXP TechSupport

Hi Frederick,

How much do your data fluctuate? Do you have a graph or a table illustrating it?

 

Issues with accuracy or drifting measurements that do not correlate with the weather or ambient pressure changes can be related to a little-known fact about light sensitivity. The sensor die is light sensitive and direct light exposure through the port hole can lead to varied accuracy of pressure measurement. Our recommendation is to avoid any exposure to the port during normal operation. For example by putting a small piece of foam over the port to block out light, but still allow the air to reach the sensor.

 

Also make sure you wait the required time before reading the conversion results (0x00 – 0x03 registers). The recommended wait time is 3 ms.

Best regards,

Tomas

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Contributor I

Thank you, Tomas.

I am seeing as much as 0.04 inHg change between readings. The reading wait time has been set as high as 10ms and the bobble of the barometric pressure still exists.  I am seeing the MPL115A1 send changed raw pressure readings very often (within 2 seconds of the last reading). I am aware of the light sensitivity.  Maybe I'm not blocking the light well enough. The sensor will be enclosed in a light tight enclosure in the final product.  I can reduce the bobble by averaging 100 readings but that is really not acceptable.

I feel that I should be able to read the conversion result within the specified wait time and it be rock solid as barometric pressure typically does not drastically change in a matter of seconds.

Have fun,

Fred

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