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Fluctuating ADC Reading for 4-20mA Pressure transducer input

Discussion in 'Sensors and Actuators' started by BHARGAV SHANKHALPARA, Jul 31, 2018.

  1. BHARGAV SHANKHALPARA

    BHARGAV SHANKHALPARA

    35
    0
    Nov 6, 2013
    Hello...

    I am working on one project of water pressure measurement, in which i used pressure transducer which gives me output between 4-20mA Current form.

    I am using one 250 ohm resistance to convert current into voltage, and than i give this voltage to ADC of arduino UNO channel 0 (A0).

    ADC reading is continuously fluctuating up to 10 decimal numbers.

    I have also check by connecting multi-meter and measure sensor current reading, for particular pressure. but current reading is stable (even not fluctuate 1 or 2 points.)

    also i have checked voltage value after 250 Ohms +Ve and ground. converted voltage is also showing very stable.

    but why ADC reading is fluctuating..?

    i am using arduino uno, i doesn't have any changes in AREF, AVCC etc...

    please suggest effective solution,

    Thank in advance.
     

    Attached Files:

  2. WHONOES

    WHONOES

    564
    111
    May 20, 2017
    Is the reference stable?
     
  3. BHARGAV SHANKHALPARA

    BHARGAV SHANKHALPARA

    35
    0
    Nov 6, 2013
    Yes, i have doest change in AREF pin, it is same as provided default.
     
  4. Alec_t

    Alec_t

    2,487
    642
    Jul 7, 2015
    If the UNO has a 10-bit ADC, the fluctuation is an error of ~1%. Noise on the ground rail could account for that.
    How close is the UNO ground connection to the 250 Ohm ground connection? Are you using twisted pair or screened cable for the inter-wiring?
     
  5. BHARGAV SHANKHALPARA

    BHARGAV SHANKHALPARA

    35
    0
    Nov 6, 2013
    Hello Alec_t..

    I actually connected 250 Ohm resistor directly on arduino board between pin A0 and Ground.

    my sensor wire is around 300 feet long, which is 2 core insulated wire, as sensor is giving 4-20mA current output, which is highly immune to noise.

    conversation of current to voltage is take place on arduino board.
     
  6. Bluejets

    Bluejets

    2,976
    578
    Oct 5, 2014
    There is a single line of additional code that will reduce analog input fluctuations in Arduino.
     
  7. BHARGAV SHANKHALPARA

    BHARGAV SHANKHALPARA

    35
    0
    Nov 6, 2013
    Please suggest me that single line code.
     
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