Motorola MPX4115A pressure sensor

[Texy]

Has anyone had experience of this device?

Although I don't know exactly my height above sea level, I estimate that it
is around 200-400feet.

According to the datasheet, I should expect Vout to be around 4.03 volts
with a 5volt supply,

but I,m getting 4.09 volts, which equates to -36 feet. This is reading
directly from the device with a high

quality DVM. Also some days it reads slightly less and other days slight
more, but never anywhere

near what I expect it to be. I can only assume that the atmospheric pressure
also plays a part in its reading.

I read in the datasheet that temperature is compensated for (over a large
range), but no mention of the

weather is mentioned.

What am I not taking into account?

(or does Motorola have a help forum).

TIA

Texy

 

[Hal Murray]

Although I don't know exactly my height above sea level, I estimate that it
is around 200-400feet.

but I,m getting 4.09 volts, which equates to -36 feet. This is reading
directly from the device with a high

I'll bet you have just discovered the barometer. They typically need
calibration/adjusting to correct for elevation and/or temperature.
Correspondingly, an altimiter needs correction for air pressure.

--
The suespammers.org mail server is located in California. So are all my
other mailboxes. Please do not send unsolicited bulk e-mail or unsolicited
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[Brian Aase]

This article should help:

http://davidbray.org/onewire/barometer.html


On Wed, 19 Jan 2005 23:43:28 +0000 (UTC), "Texy"
<texy@nospam.btinternet.com> wrote:

Has anyone had experience of this device?

Although I don't know exactly my height above sea level, I estimate that it
is around 200-400feet.

According to the datasheet, I should expect Vout to be around 4.03 volts
with a 5volt supply,

but I,m getting 4.09 volts, which equates to -36 feet. This is reading
directly from the device with a high

quality DVM. Also some days it reads slightly less and other days slight
more, but never anywhere

near what I expect it to be. I can only assume that the atmospheric pressure
also plays a part in its reading.

I read in the datasheet that temperature is compensated for (over a large
range), but no mention of the

weather is mentioned.

What am I not taking into account?

(or does Motorola have a help forum).

TIA

Texy

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