Thursday, October 8, 2009

Reading 2 sensors

So, I have connected 2 sensors and reading these for about 5 days now. One is outside the window (yellow) and another is connected to radiator (red). I made even a script that reads sensors every 10 minutes and sends reading over internet to public net and saves it to MySQL database. And using XML/SWF Charts, I can see live chart on readings. First problem I noticed right away is outside sensor. Currently here in Estonia, outside air temperature is around 10°C, but sometimes sun comes out and heats outside sensor up to about 25°C. That means that I have to find some better place for this sensor, where sun can't shine on it. Also, I think I should rewrite my script so that when reading outside sensor, then on saving it to database, It should save average value of current and last two readings.
Here is another chart, where temp1 is live reading of outside temperature and temp2 is average of last 3 readings. As you can see, temp2 is little bit smoother.

About my radiators, I found out that they are switched off for night. Every day 23:10, they are turned off and temperature starts to fall. And from 6:10 they are turned on and temperature rapidly raises. I am thinking that if I want some more energy efficiency, then I would also turn off radiators from 9:00 on working days and turn them on on 16:00, about hour before I'm home.


  1. Hello,

    I'm pretty much in the same situation like you now : I've got a few DS18S20 thermometers at hand, and I've got one of them connected to my compter and got my first readings (and even graphs in Cacti).

    What I'm now concerned with, before running this one long CAT5E ethernet cable throughout the house, would be to know how far you got in "parasite power" mode (Vdd and GND wired together) ? Don't you need an additional power supply ?

    Thanks in advance for your input... I'd really like to get this done and have my computer control the heaters of my house :-)


  2. Hello,

    Would it be possible to have a copy of your script for reading sensor data and inserting into a MySQL database. I'd be really appreciative.

    Many thanks


    my email is:

    jonathan at learningspaces dot net

  3. Hi.
    I to would'nt mind getting my hands on these scripts. :)
    I am doing a similiar project with Raspberry Pi, i am just waiting for my DS9490R to arrive by mail. :)

    My mail address is

    Kind regards