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I just want a recommendation for an analog air pressure transducer with a range from 0-10 bar (to be used in an electro-pneumatic system) to be connected easily with RPi 4 (compatible with RPi 4) and not expensive ($10-15)!?

I also found that in other APPs like the one in the second photo that they use a level shifter between RPi & ADC, so do you think that I have to add it to the schematic here or the ADC can be connected directly to RPi!?

Circuit schematic

I want to do a project like this one so that I can read the analog value of the pressure through RPi. I suppose also to use Codesys to program RPi using ladder language (not to use Python), I am not sure until now if that is possible or not.

Here is the link of the YouTube video explaining the project in the photo below Raspberry Pi Analog Water Sensors ADC Tutorial.

Screenshot of Fritzing diagram from video

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  • not expensive compared to what? I assume you've found some that are "too expensive"?
    – Bravo
    Commented Dec 15, 2021 at 9:23
  • Curious what this is; can you give an example / link of the device you are looking for?
    – 0__
    Commented Dec 15, 2021 at 22:38
  • Do you want to measure atmospheric pressure, or something else? If it's something else, what pressure range do you need?
    – nekomatic
    Commented Dec 16, 2021 at 17:06
  • -I would like to measure air pressure in my electro-pneumatic system and I want to read this value through RPI4
    – ibrahim tahoun
    Commented Dec 17, 2021 at 13:53
  • - Not expensive (in the range of 10-20$) for a small project
    – ibrahim tahoun
    Commented Dec 17, 2021 at 14:04

1 Answer 1

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I am assuming the TEP 36, a temperature sensor is a sub on the schematic for the pressure sensor. If so per the schematic and the data sheet you should be all set, the device works at 3.5v and 5V. Running both at 3.3 volts as your schematic shows will be fine. I would also recommend you add some bulk and high frequency bypass capacitors on the VCC supply (Vin & Gnd), something in the 100nf and 4uf range.

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  • thanks Gil for your answer. you are right, it is a temperature sensor that I need to substitute with a pressure transducer. I am just confusing a little bit because I know that any microcontroller reads the digital or binary signal as a voltage (0=0V & 1=5V) and RPI can only receives a max voltage of 3.3V.
    – ibrahim tahoun
    Commented Dec 20, 2021 at 9:25
  • You can use any pressure sensor that will do what you with a DC output. The A/D you chose has a Vref and Aground, these supply the SAR (Successive Approximation Register) in the A/D. Your sensor's analog voltage will be referenced to this voltage. Be sure all grounds are connected. The A/D will give you a a digital value that is based on the reference voltage. If it is at Vref or above you should get 1023. If it is 0 you should get 0. If in between the count will reflect that. Get this: (SAR) Analog-to-Digital Converter by Microchip Technology Inc, I believe it is free and will explain a lot.
    – Gil
    Commented Dec 20, 2021 at 20:16

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