Is it possible to use 2 HX711 modules with one raspberry pi?

Discussion in 'General Electronics Chat' started by sohamkul, Oct 3, 2016.

  1. sohamkul

    Thread Starter Member

    Jun 24, 2016
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    Hello ,

    I am doing a project of data acquisition system and i have two load cells(Sensors) ,now we can only use one HX711 module for one load cell , so i want to ask if it is possible to use two HX711 modules for two load cells ? also can i read the data from two modules simultaneously ?

    Thank you in advance .
     
  2. ci139

    Member

    Jul 11, 2016
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    (i'm trying to look helpful - don't let it bother you)

    http://hivetool.org/w/index.php?title=Interface_the_HX711_to_Pi -- it looks like they have succeeded in something
    ftp://imall.iteadstudio.com/Sensor/IM131029002/DS_HX711_AD_Module.pdf -- they say serial interface that likely is not SPI nor I²C -- thus you can't use (likely can't) addressed weighing boards on a same bus -- but the rate 10/80 suhouldn't be difficult to mux 10x/80x - preserving your RAW "serial IN" in FIFO per Hx711 (? for any interface timing problems)
    -- if you mux the rate futher you may store a "process clock" for fifo record
    -- for timing the events -- based on weighing values -- ASAP - is possible to add more Hx711 , analog mux the sensor infront , tweak timing by complex clocking algorithm -- to sync. HX´-s send 1 after another . . .
     
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  3. dannyf

    Well-Known Member

    Sep 13, 2015
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    Yes, and even more.
     
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  4. sohamkul

    Thread Starter Member

    Jun 24, 2016
    43
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    I will be using two 5 v supplies on the raspberry pi so i need only two but will the whole system be fast ??
    i need to get dtat simultaneously and plot graph ..

    Thank you .
     
  5. ci139

    Member

    Jul 11, 2016
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    Is it a theoretical project or someone actually has to use/trust later what you are building?
     
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  6. sohamkul

    Thread Starter Member

    Jun 24, 2016
    43
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    its real !! someone actually has to use what i am building ....
    i just need two HX711s to work great with raspberry pi ...
     
  7. ci139

    Member

    Jul 11, 2016
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    ? something is stationary on a scale , ? rolls/flows over scale, ? bounces on/off the scale
    e.g. what or where in time is the part of weighing that needs to be exact ? (complex wording) ? what are you weighing
     
  8. sohamkul

    Thread Starter Member

    Jun 24, 2016
    43
    2
    No, its not stationary i am weighing for sure but i need quick response three values per second ...and i need the changes in load cell output as fast as possible.....
     
  9. ci139

    Member

    Jul 11, 2016
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    i can't advise you with raspberry
    i was just curious if you are aware what you're doing
    as with everything your system performance accuracy is what you know about your hardware and the combination of
    so altering the setup changes you error formula
    usually it's years of lab to say anything certain about
    e.g. to know whether the average of 4 or 14 samples gives the least error

    the http://image.dfrobot.com/image/data/SEN0160/hx711_english.pdf does not list any certificates -- so it's your word and knowledge and your client's trust until you get - if so - your product certified
    a side find - some specs
     
  10. ci139

    Member

    Jul 11, 2016
    341
    38
    a correction
    you only need to be certified in EU if your weighing results affect the financial calculations , perhaps in some other cases
    i also can't tell if the electronic circuitry from sensor to result needs special certificates or just approval to be used in such system (basically it's that you can prove that the share part error corresponds to limits you provide - that in turn requires a specific lab work ...)
    whatever the case - the above also applies the quality of your final device - it is obviously good to know the error of your system even if the certification is not required
    it's good if you already know all about it - you just seem to change your setup every other week

    there are many converter IC-s between common interfaces
    i donno about raspberrys I/O - but the google can like find all types of examples ?
    - the random pick
    http://www.siongboon.com/projects/2013-07-08_raspberry_pi/index.html
    http://www.robert-drummond.com/2015...control-your-gpio-io-ports-over-the-internet/
     
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  11. ci139

    Member

    Jul 11, 2016
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    basically the answer is correct for a general question ↑

    if you want anyone to start moving their brains - ask a specific question and/or what and in which context you intend to achieve
    (there are 100 and more ways to do things - you eighter receive this or a simplified form of - as above↑↑)
     
  12. ci139

    Member

    Jul 11, 2016
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  13. sohamkul

    Thread Starter Member

    Jun 24, 2016
    43
    2
    @ci139 I interfaced Hx711 with raspberry pi and it works like charm !!! Thank you !!
     
  14. ci139

    Member

    Jul 11, 2016
    341
    38
    -.- thanks for telling
     
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