Pressure not recorded

[joalegri]

Hi,

I am currently working with a MPX5500DP sensor to measure pressure but the analog reading from the Arduino Uno is never changing with and without any pressure applied. I included screenshots of my code along with pictures of my wiring. I used the transfer function from the datasheet to calculate the pressure if Vout is known and used the circuit from figure 4 with the decoupling capacitors. In the circuit pictures, I have the black jumper cable connected to ground, the red jumper cable connected to the 5V pin, and the blue jumper cable connected to analog pin 5. I did a bunch of Google searches and went through the datasheet numerous times but can't find any leads.

Thanks,

Jorge

[TomasVaverka]

Hi Jorge,

Your wiring seems to be correct as well as your code. It is also correct to get ~0.2V on the output with no pressure applied. Then if you increase the pressure difference between P1 and P2, the output voltage should increase. However, please note that the MPX5500DP is not very sensitive (typ. 9mV/kPa), so you need to apply pretty high pressure in order to get significantly higher output voltage (e.g. 100kPa between P1 and P1 corresponds to 0.9V or 1.1V on Vout).

If the output voltage still remains rather constant around 0.2V, then the sensor might be defective and you will have to use another one. But my guess is that you are not applying enough pressure to get higher output voltage.

Best regards,

Tomas