# Pressure sensor 3 wire Honeywell PX2 as depth controller for Underwater vehicle

Dear All
I am new in this forum. I am using a pressure sensor Honeywell PX2EF1XX030PAAAX with 3 wires (red-supply vol (0.5~4.5V), black Gnd and white-output). It is absolute type and maximum operating pressure is 30 PSI. I want to use it for maximum depth of 5 m underwater. It has an accuracy of ±0.25 %FSS.
Can anyone guide me how to connect it with arduino Mega and data logger and how to get readings after each 3 inch depth of water.
Thank you

Connect red to the 5volt pin, black to ground, and white to A0.
Start by reading the atmospheric pressure.
That value will be the offset.

If the sensor has a range of 30psi, and a span of 80% of VCC (VCC - 10% and ground + 10%), and you read the sensor with Arduino's 10-bit A/D, and atmospheric pressure is 14.7psi, then:
rawValue = 1024 * 0.8 * (14.7 / 30) = ~410 at atmospheric pressure
See if you get that with the atached (untested) code.

rawValue of 1024 * 0.9 (VCC - 10%) = ~922 is reached at 30psi.
30 - 14.7 = 15.3psi of water depth.
So 922 - 410 = ~512 A/D values spread out over 15.3psi of waterdepth.
Or 512 A/D values per 423.5inch of water.
That's the theoretical resolution with a 10-bit A/D.
Leo..

``````int rawValue; // A/D readings

void setup() {
Serial.begin(9600);
}

void loop() {
rawValue = analogRead(A0);
Serial.print("Raw A/D is  ");
Serial.println(rawValue);
delay(1000);
}
``````

Thank you wawa, Nowcan you please guide me how can I transfer the output values to data-logger ?

First get it working with A/D values.
Then add a formula to calculate the depth in cm? or inches?.
Then think of logging it.

What A/D values did you get without applying pressure to the sensor.
Do the A/D values go up with some air pressure (blow with your mouth).
Leo…