| Author |
Message |
Texy
Guest
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 Posted:
Wed Jan 19, 2005 11:43 pm Post subject:
Motorola MPX4115A pressure sensor |
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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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Brian Aase
Guest
|
| Posted:
Thu Jan 20, 2005 6:47 am Post subject:
Re: Motorola MPX4115A pressure sensor |
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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:
| Quote: | 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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Hal Murray
Guest
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| Posted:
Thu Jan 20, 2005 8:51 am Post subject:
Re: Motorola MPX4115A pressure sensor |
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| Quote: | 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.
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