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Multiple analog sensors on nodeMCU - multiplexing

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  • Multiple analog sensors on nodeMCU - multiplexing

    I am thinking out how to build a wifi connected temperature control for my meat smoker. I need 2-4 temperature probes. At minimum, one for the grill inside temperature and one for the meat I'm smoking. More to get more precision or do multiple pieces of meat at once. The probes are analog sensors.

    Using the nodeMCU is a problem in that there is only one analog pin. But the nodeMCU is perfect as far as wifi and HS3. I ran across this technique of multiplexing analog sensors. I use the API sketch so I should be able to implement this easily enough. If it works, now I'll effectively have multiple analog devices.

    Just thought I would pass it along.

    http://www.instructables.com/id/ESP8...nalog-Sensors/

  • #2
    The code example in the above is written in LUA. Below is a link to the same concept but the sketch is written in C++.

    http://www.instructables.com/id/Mult...e-Analoge-Pin/

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    • #3
      And this YT video talks about a hardware solution to adding analog pins to a nodeMCU.

      It uses a little digital to analog converter card. Costs < $5 on ebay.

      https://www.youtube.com/watch?v=_J8uGesYvl8

      http://www.ebay.com/itm/ADS1115-4-Ch...i/201536592302

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      • #4
        The other option is to power the sensor from the digital output pins, that way if you select one of the pins to on and measure the output. The only issue with that is that you have to make sure you are reading what you think you are reading.
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        • #5
          Originally posted by mrhappy View Post
          The other option is to power the sensor from the digital output pins, that way if you select one of the pins to on and measure the output. The only issue with that is that you have to make sure you are reading what you think you are reading.
          That would work for some sensors but not others. I have several air sensors that I have plans for. Several of them need power all the time since they use heat to detect changes in the air. If you were to be cutting power on and off repeatedly, I doubt the readings would be accurate.

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