MPX5700DP Differential Air Pressure Sensor

Other Hardware Sensors
1

Hi can someone help me with this sensor I can't find any code or help on the net I have a datasheet that reads like this

Accuracy ±2.5 %
Analogue Output 4.7 V
Housing Material Epoxy
Maximum Operating Temperature +125°C
Maximum Pressure Reading 700kPa
Media Measured Air
Minimum Operating Temperature -40°C
Minimum Pressure Reading 0kPa
Output Type Analogue
Pressure Reading Type Differential
Response Time 1 ms
Supply Voltage 4.75 → 5.25 V dc
Terminal Type PCB

I need to output the analogue signal to psi to my serial monitor

here's a link for the item

http://www.ebay.co.uk/itm/MPX5700DP-Differential-Air-Pressure-Sensor-Freescale-Arduino-MPX5700D-UK-Stock-/121626002591?

2

Connect the sensor to 5volt, ground and analogue in (A0).
And use Examples > 01.Basics > AnalogReadSerial.
See what you get in the serial monitor.
Try different pressures.
You will have a "zero pressure" value (~45), and a "700kPa" value (~980).
If that works, then think of mapping that to a psi/bar/kPa value.
Leo..

3

Thanks for the reply Wawa

I haven't yet purchased it as it pretty expensive for a sensor but I need it for my project I was worried

that I may not be able to use it as I cant find any information on the WWW

I'm guessing that it will give me a reading of 0 to 1023 and somehow I need to convert that to psi /?

I will buy one and have it a go

4

http://cache.freescale.com/files/sensors/doc/data_sheet/MPX5700.pdf
If you look at the datasheet, you will see that the output is not the full range from 0 - 5volt.
More like 0.25 - 4.75 volt, so 0 - 7bar will be ~50 - ~975.
Still 90% of the usefull A/D range with default 5volt Aref.
I suppose this gauge model is for an air compressor.
There are other models for other pressure ranges e.g. 5100 or 5050.
Post your code. Maybe we can improve it.
Leo..

5

Can I know if i this sensor can be used for making a digital tire inflation system.

6

The pressure is 0 to 700kPa, which results in a voltage of 0.2 to 4.7V.
The pressure span is 700kPa, for a voltage span of 4.5V (according to datasheet).

Get the pressure from the voltage.

  int rawADC = analogRead(A0);
  float volt = (float) rawADC * 5.0 / 1024.0;
  float kpa = (volt - 0.2) / 4.5 * 700.0;   // minus offset, divide by voltage range, multiply with pressure range.

The result improves when averaging is used for these sensors.

  const int numAvg = 20;
  unsigned int total;
  total = 0;
  for( int i=0; i<numAvg; i++)        // maximum 60 will fit in a unsigned int.
  {
    total += analogRead(A0);
  }
 
  // Add half a bit. This is correct, but trivial.
  total += numAvg / 2;

  float volt = (float) total / (float) numAvg * 5.0 / 1024.0;
  float kpa = (volt - 0.2) / 4.5 * 700.0;   // minus offset, divide by voltage range, multiply with pressure range.

Do not connect the unused pins. Don't connect them to ground.

7

hello , I was following your discussion from the outside as they are interested in the project , in particular, are in possession of a BMW motorcycle and with this project I wanted to try to align the cylinders , are already in possession of the sensor mpx5700dp , if not too much to ask you to publish complete the sketch so maybe I can try to adapt it to my needs and even share it. I would be very grateful.

8

Where do you get the volt*5/1024 to convert to pressure values?
I am confused about how this sensor works. Is there an ability to display 2 output values? The output of high and low ports?
thank you