My weather station project

Discussion in 'The Projects Forum' started by turbine2, Jun 11, 2014.

  1. turbine2

    Thread Starter New Member

    May 20, 2014
    7
    0
    Hi all,
    I thought I would just put this in place while I get my thoughts fully mapped and as a reminder to me to get something done.
    I'm looking to build a replacement weather station for the one I have that keeps failing. I've had a look around the internet and decided (for various reasons) on the following.
    External temperature (probably based on a Dallas 18B20 as I've some of those knocking around)
    External Humidity (not sure on this, I've picked up a cheep DHT111 but I'm not convinced on it at the moment)
    Barometric pressure (looking at the options, a BMP085 appears to be the unit of choice)
    Rain rate (using a tipper and switch)
    Air speed and direction (using an ultrasonic setup as this is the bit that fails the most).
    I'll use an Arduino initially but probably go to a PIC directly eventually as a dedicated circuit).
    The only bits I haven't decided on at the moment are the method of data transfer (wired or wireless) and what to do about power. For testing purposes I will probably go with wired data transfer, but wireless is looking interesting. For power I'm not sure if I'll go with batteries (a pain, but...) or (and the way I'm leaning at the moment) a 12v solar panel with a battery backup (as I've got the 12v panel doing nothing anyway).
    I'm going with an ultrasonic wind sensor as the bit that fails most often is the anemometer, either as the bearings on the wind cups fail or as the direction vane sticks. Plus, this is an electronics project, so I want to avoid mechanical parts and, well, why make life easy eh?
    So far I've managed to get the temperature, pressure, humidity and arduino working on the bench, so my next step will be the anemometer.
    Watch this space for more as I learn through (some) trial and (probably a lot more) error.
     
  2. turbine2

    Thread Starter New Member

    May 20, 2014
    7
    0
  3. Sensacell

    Well-Known Member

    Jun 19, 2012
    1,132
    267
    I would run it all over a single CAT-5 cable.

    Use 6 of the wires for power, run 24 volts, use a switching regulator to create a clean local power supply +5, +12, whatever.

    Use the remaining 2 wires for an RS-485 com link to get the data back.
     
    Last edited: Jun 11, 2014
  4. sirch2

    Well-Known Member

    Jan 21, 2013
    1,008
    351
    The BMP085 and its replacement the BMP180 gives temperature and pressure, so no need for the 18B20.

    Why not got to an ATMega328 on a standalone board rather than PIC since your Arduino code will run on it?
     
  5. turbine2

    Thread Starter New Member

    May 20, 2014
    7
    0
    Sensacell, I may well go down that route as I'll need to get power up there somehow and I'm hoping that my new office will let me run some new cable too. At the moment it's more down to logistics than anything else on that decision.

    sirch2, it's a good question and the only answer I have at the moment is that I know how to burn a PIC but I've not tried with an ATMega.
     
  6. MrChips

    Moderator

    Oct 2, 2009
    12,449
    3,364
    Why not use a commercial wireless weather station? Mine runs off a standard 9V battery that lasts for years.
    (The rain gauge, temperature, pressure and humidity sensors not shown below.)

    [​IMG]
     
  7. sirch2

    Well-Known Member

    Jan 21, 2013
    1,008
    351
    To burn a Program from the Arduino IDE to a bare ATmega you just need a programmer, which can be an Arduino board (yes you use the Arduino as a programmer) or a dedicated programmer such as the the usbtinyisp. You connect up 6 pins (Vcc, Gnd, Reset, SCL, SDA, CE) and then hold down shift while clicking the upload button. Whatever ran on the Arduino will run on the bare chip.

    I probably missed a step in that you probably have to configure the programmer in the IDE but apart from that it is very easy.

    I missed one other step, which is optional anyway but the easiest way of setting the fuses correctly is to use the "Burn Bootloader" option in the Arduino IDE. You only need to do this once for a new chip, you DO NOT need a bootloader, in fact it will be overwritten anyway but it sets all the fuses correctly without you having to work out which need setting to what.

    The whole process really is trivially easy.
     
  8. turbine2

    Thread Starter New Member

    May 20, 2014
    7
    0
    MrChips: The problem I have is that the hobbyist level ones I've used like the one you've posted don't appear to do well in the UK environment. Of the two I've tried so far both have suffered bearing failure and because they're difficult to get to I can't maintain them. To get a commercial ultrasonic wind sensor would be too expensive for the use I would get out of it so I don't want to go down that route. Plus, I kind of want to get back into hobbyist electronics again having not done it for years and I was looking for a project, so there's the "because it's there..." argument :)

    sirch2: I've got a PIC burner, but if burning an ATmega is that easy then I'll go down that route instead.
     
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