====== MPS20N0040D Pressure Sensor ======

{{:soft-robotics:sensors:sens-mps20n0040d.jpg?400|}}

===== Description =====

This is a cheap yet ubiquitous pressure sensor based om a Wheatstone bridge. Unlike the [[soft-robotics:sensors:mis-2500|MIS-2500]], it requires amplification using an Op-Amp.

===== Datasheet =====

{{ :soft-robotics:sensors:mps20n0040d-s_datasheet.pdf |Download here.}}

===== Circuit Design =====

After plenty of reading and experimenting I came up with the following LM358 based circuit that I am satisfied with.

==== Pinout ====
This pin diagram is for the version of the sensor that I ordered.

{{:soft-robotics:sensors:mps-pinout.png?400|}}

==== Circuit ====
The circuits I have seen online use two connections to the LM358, first as a differential amplifier and then as a normal amplifier. 
I believe that I can manage with just differential amplification, because it provides both amplification to the signal and eliminating the 2.5v offset of the output.

**The following setup is for 3.3v on the Teensy**

{{:soft-robotics:sensors:pressure_sensor_connection_avner.png?800|}}

*Based on the image in "The answer is 42"

==== Breadboard image ====

{{:soft-robotics:sensors:breadboard_pressure_sensor.jpg?400|}}

* I also added 100Uf capacitors because seems like that was recommended.


==== Raspberry Pi Circuit ====
To connect the pressure sensor to a Raspberry Pi, the ADS1115 board may be used.
Below is a Fritzing image of the circuit:

{{:soft-robotics:sensors:mps20n0040d_pressure_sensor_-_raspberry_pi_bb.png?400|}}

The pressure is measured as a differential pressure, counting the difference between A0 and A1.
The Fritzing sketch is available [[https://version.aalto.fi/gitlab/peleda1/puppetbots/-/blob/439b3ef9cbe7f46207e2e06fb6bcbe6fcdbf993c/prototype/fritzing/MPS20N0040D%20Pressure%20Sensor%20-%20Raspberry%20Pi.fzz|here]].



===== Further info =====
  * [[http://henrysbench.capnfatz.com/henrys-bench/arduino-projects-tips-and-more/op-amp-basics-for-arduino-hobbyists/|Op Amp Basics for Arduino Hobbyists]] 
  *  [[http://langster1980.blogspot.com/2014/11/how-to-use-pressure-sensor-with.html|The Answer is 42 - How to use a pressure sensor with a Microcontroller (MPS20N0040D-D)]]
  * [[https://softroboticstoolkit.com/pds|Soft Robotics Toolkit - Pneumatic Deformation Sensors]]