Sensor for barometric pressure

RDL2004

I was thinking of adding a barometer to my little "weather station". My first poking around on the internet led me to the Freescale (Motorola) mpx4115. I found quite a bit of info and it looks like a good place to start. I was just wondering if anyone else had tried it or if maybe there was a better choice.

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- Rick

Harrison.

I use a MPX4115AS in my weather station to measure barometric pressure. It is used in conjunction with a 10bit adc (gives me about .07 inHg steps). I am thinking about upgrading to a 12bit adc to get better accuracy.

Here is a code snippet of how I calculate the pressure using a 10bit adc directly connected to the sensor output. (This is CCS C code for a PIC16F876).

float get_barometer() {
   long raw;
   set_adc_channel(0);
   delay_ms(1);
   raw = read_adc();

   return ((float)raw * 0.03212) + 3.12 + BARO_LOCAL_OFFSET;    //calculate barometric pressure in inches hg
}

I ordered my sensor from www.phanderson.com. My weather station is at: wx.harrisonpham.com/ .

Harrison

Paul Baker

I have not worked with barometric pressure sensors before, but here is one which has 17 bits of accuracy, includes temperature·compensation and provides the data (pressure and temperature) in digital format: http://www.sparkfun.com/commerce/product_info.php?products_id=8161

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

N0QBH

I built my own weather station a few years ago and used a MPX4115A sensor along with an amplifier to get the resolution I wanted.
Works great. The amp circuit is attached as well as a spreadsheet the designer included. The resistor values I used are for 1000' above sea level and have to be changed if your altitude is over 3000'. My program is in PIC assembly, so I won't be any help coding it in BASIC.