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Measuring atmospheric pressure

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Hi. I have a pic micro controller and motorola's differential sensor MPX5100DP. Sensor measures pressure up to 100kPa and it gives output voltage from 0.2-4.7V according to datasheet.

Can i connect this sensor (Vout pin) directly to ADC input of micro controller?
How do i measure atmospheric pressure with it? I know i need to get some sort of constant pressure on one of inputs of sensor but how and with what to achieve that?
Thanks in advance.
 

Simpe truth: You can't measure atmospheric (absolute) pressure with a differential (relative) pressure sensor. An absolute pressure sensor can't work without a vacuum at it's reference port. For this reason, it's a bit more expensive than a differential type, but also available in a wide choice of types.

P.S.: A supplement. A hermeticly closed box with constant pressure would act as a thermometer, p ~ T. Refer to elementary physical laws. The only temperature independent constant pressure is zero pressure - a vacuum.
 
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Have no idea how to make hermeticly sealed chamber? Do i need a voltage divider when connecting sensor?
 

Have no idea how to make hermeticly sealed chamber?
Click to expand...
Simply assume, that you don't have the technique to make it.

Freescale MPX5100A is an example of an absolute pressure sensor. It has a sealed vacuum cavity inside the pressure sensor chip. See a drawing from a Freescale datasheet:



Do i need a voltage divider when connecting sensor?
Click to expand...
MPX5100 is an "integrated" pressure sensor with buit-in amplifier. It's specified for 5V operation and has a 0 - 5V output. So it's perfectly suited to be used with a 5V microprocessor and it's internal ADC.
 

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