More than one sensor on one arduino pro mini

  • I hope this is the right sub forum πŸ˜‰

    is it possible, to connect 1 to n sensors to one arduino pro mini? What do i want to archive?

    I have some "clusters" of plants in my home. I want to use the moisture sensor ( to monitor the single plants. I can't imagine, that using one full sensor (arduino + sensor + wireless module) is the way to go? This will make it quite annoying, as every arduino will need a full power supply, wiring and the costs of the arduinos and NRF itself.

    so what i want to know, is there a setup like this:
    (arduino + nrf24L01+) --- (moisture sensor) --- (moisture sensor) --- [repeat n times] --- (moisture sensor)?
    so i have one wire connecting the sensors to the arduino?

    4 sensors/plants for one arduino pro mini should be possible without problems (i want to use the analog pin, and the pro has 4 analog inputs) but extend this amount would be awesome.


  • Of course you can.

    You will have to declare how many sensor child are there on one arduino and voila.

    Now go and learn how to achieve that.

  • thx 4 responding πŸ˜‰

    what do you mean with "of course i can"?
    N sensor childs? Do u have a buzzword helping me with my research?
    Or do you mean the "max 4 sensors limited by the amount of (analog) input pins" solution?


  • Hero Member

    Have a look at the dallas temperature sensor sample. This sketch reads several temperature sensors via onewire and sends the values as so called child sensor values to the gateway.

  • Admin


    If you are going to use the analog input you are limited to the number of analog inputs on the board that you are using. Unless you are using an analog multiplexer like 74HC(T)4051

    You can not daisychain analog input from one sensor to the next one.

  • hmm ok this means a max of X plants per arduino pro mini.

    when reading the pro mini specs:
    X = 6 (thats what the summary says)
    X = 8 (that what A0-A7 should be πŸ˜› )

    Some general question:
    Whats makes a sensor useable with oneWire? why does the a temp sensor work and the moisture sensor not? is it, because the the temp sensor uses digital input?

    thx for the help

  • It is because moisture sensor is analog, while OneWire is digital tech. on chip.

  • @dakky The official Arduino pro mini does not breakout the pins for A6 or A7. You can get off branded pro mini's that do offer these pins.

  • says otherwise πŸ˜„

    or to be correct: the image says otherwise (have a look at the back of the board), the description says 6 Analog pins

  • It's my understanding that since the ATmega168/328P in the DIP package does not physically have the pins to support A6 and A7, they originally decided not to put these on the mini. It seems that newer revisions of the mini now include these. If you take a look at the schematics on the page you linked above, you can see the newest design version is dated 4-9-2014.

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