Airspeed from MPX5500DP differential pressure sensor using a PIC16F88

[mackrackit]

As an example, using the ISA standard sea level conditions of P = 101325 Pa and T = 15 deg C, the air density at sea level, may be calculated as:

D = (101325) / (287.05 * (15 + 273.15)) = 1.2250 kg/m3

Above is from
http://wahiduddin.net/calc/density_altitude.htm

[aratti]

D = (101325) / (287.05 * (15 + 273.15)) = 1.2250 kg/m3

Dave you are correct, fluid density is temperature dipendent. I made a wrong assumption, Alain forget my previous post.

Al.

[marcusvm]

Thank you all for the help.

I'll explain to all of you what this is all for. What I am have been building this semester is a open circuit wind tunnel for a mechatronics class. We have several criteria that it has to meet, which I will spare you the details of. But, the basic set up I have at the moment is that I have a DC motor spinning an RC plane prop to create the wind with a PWM function off of a PIC16F88. We are using a keypad to control the different speed settings and LED's to display the speed setting for the keys pressed. Then we have another PIC16F88 running a pitot tube set up which consist of a differential pressure sensor, op amp, voltage regulators, PIC16F88, and then an LCD for outputting displays and for helping as a "heart beat" monitor. We had a deadline coming up this Tuesday for an extra %10 on the project if we had everything function. I got it all locked down tonight and should be set for the deadline.

Alain - I realized when I started the programming for the sensor last week that I had one that was WAY over sized for what I was using it for. I got it as a sample and am happy it has gotten me to where it has, but I am planning on ordering a more realistic one next week for the final presentation. Realistically I only need one that hits 1 psi because I am only planning on hitting 60 mph wind speeds. Its a matter of finding one that can give me what I want without the high cost.

Al - We are indeed working with air and yes 1.2 is the density of air. That is even straight from my fluid dynamics text book.

Again, thank you all for the help! I have most of the stuff completely ironed out except for calibrating of the pitot tube (probably need a better pressure sensor ). But now with the month left in the project it leaves me the chance to add in safety features such as a open door sensor, tachometer, refine the pitot tube setup and possibly a data acquisition set up.


I doubt I can help many people on here with any programming, but I do have a lab book that has examples for PWM and other simple functions to fun things. Let me know if there is ever anything I can help with.

-Marcus