Hardware advice for newbe

  • Hello all,

    I would like to make my first mysensor project. Since I am a complete newbe to this I hope you can help me get started. I have read a lot on the website, but would just like to get some things clear.

    My idea;
    I would like to measure the humidity and temperature of 5 rooms (maybe even more rooms) with sensor DHT22. A convenient place to measure for me would be the ventilation vent in the rooms. I can still easily access these en I can place the sensors out of sight.
    I would like to connect the five sensors to one audrino board that is located at a convenient place. At this place Ethernet cable and power is available. The readings I would like to monitor in Domoticz, which I have running on a rasberry pi, in another room.
    I prefer this set up and not an separate functioning sensor in every room since than I have to power everything by batteries (which have to be replaced) and take more room in the vent.

    My questions / uncertainties;
    1 After reading the website I believe my idea is feasible (even for a noob), right?
    2 What is the best board for my project (size does not matter)? Audrino uno ethernet? or Audrino uno R3 with shield? or?
    3 Can the distance between sensor and audrino be several meters? (Maybe use ethernet cable for this)
    4 Other advice?

    Thanks in advance for any answer!

  • @Jasper-van-Winden
    In theory it should work. The question is just how long the wires to the DHT22 sensors are. I am not sure if anyone tried this as the whole idea behind this project is having simple sensors which talk via radio.
    I would guess if the wires are too long, the signal and/or power will be not high enough to get reliable readings.
    But if it would work via ethernet cable then why not connecting the sensors directly to one central arduino and just push that via http to your controller? I do not see any use of MySensors here if it will be wired...

    maybe I am wrong?

  • @parachutesj

    The longest cable will be 10meters.
    The central audrino is exactly my idea. Why? Cheaper, easier to acces, not much space where i would like to place the sensor, no battery replacement needed and ethernet cable available.

  • @Jasper-van-Winden
    maybe you could use the cat5 cable to power some local arduino nanos with 12V, this should be probably enough to get them running. so you could save the batteries. I doubt that with 10m the DHT will work. but try it out...

  • @Jasper-van-Winden
    well I was wrong. I had 13m CAT 5e cable laying around and just tested it with one DHT22 and it seems to be working:

    alt text
    alt text

    To consider:
    The Arduino Nano is powerd with a stable DC supply and it is only one DHT22, could be different outcome when you connect 5 of them all with long wires.