Home Automation
1-wire (ibutton)

Home Automation 1-wire


When looking at Misterhouse software I came across a lot of different products that the software supported. One line of particular interested is the 1-wire network and related products. There a pile of very cool products that you can put on a 1-wire network. So technically what is 1-wire? Read this... (pretty heavy) http://www.maxim-ic.com/appnotes.cfm/appnote_number/3989.

 

OK so what the hell does that mean? www.arunet.co.uk/tkboyd/e1dsu.htm

 

So now that you kinda understand what 1-wire stuff is and how it works we can start looking at some of the cool items that you can get.

 

Let's start at the beginning here is how you plug the network into your computer. This is a serial to 1-wire adaptor, this is what Misterhouse communicates through. It has a serial connection on one side and a RJ12 connector on the other. This is all that you would need to start communicating with a device. There is also a USB device that does the same thing, I am unsure of the Misterhouse support for that device. Click on the item to learn more about it...



So now that you have your computer talking the 1-wire network you can start putting some devices on it. When I got my network running I jumped in with both feet and ordered the weather station. My main purpose for getting into 1-wire stuff was for this item. Because I use my home automation system to control my sprinklers I wanted to have a way to abort the sprinklers cycle if the wind is to high, or turn on more often if the temperature is hot. This device will measure wind speed, direction and temperature (probably in the sun, depending on were you mount the weather station). Out of the 1-wire items that I ordered this one if probably the most difficult to physically setup. You will want to have this out in the open preferably up high above the tree line so the wind measurement is accurate. Here are some ideas for getting your weather station into the air.

www.txwx.com/downloads/1_wire_instruction_manulal.pdf

 

How to setup a reliable network:

http://www.maxim-ic.com/appnotes.cfm/appnote_number/148

 

There are a pile of links at the bottom of this page:

http://www.carterlake.org/stationsetup.php

 

 

 


Now that my sprinklers know if it is to windy or not I also want to know if just rained recently. So I also puchased a rain gauge. This item has been modified so it could talk to the 1-wire network. It originally came with a wired counter that just counted how many clicks on the rain tipper. It is a very simple but accurate design.
 





So I purchased all of these parts and sat down to get things tested and found out very quickly that I needed to do a little more designing before I ordered. I misunderstood some limitations of 1-wire. So I went back to hobby-boards.com and ordered some more stuff. It's like Christmas every couple weeks...

 

So now I ordered the six port hub (shown below) that allows me to have several legs to my 1-wire network. Yes you can put dozens of devices on a single 1-wire run (cat5), but after that cable is run and you want to add on to your network you need to be really close to that wire. From what I have read each device cannot be more that a couple inches off of the main run.

 

Support is built in to Misterhouse, you just plug this unit in and it automatically starts switching the three channels and Misterhouse recognizes everything that is plugged in. It is a very sweet solution. So now I can have 1 wire runs going every directions without having to over plan the network. I think it is worth the money.

 

Here is a picture of the power injector, this just adds power to the system. It is suppose to makes the sensors more accurate. Some items will not even run without addition power.



I will be ordering some more of these next two items. The first one is a four port relay board. This unit just plugs in like everything else, if the run is short enough then you can just use power from the power injector or one of the hubs to energize the relays. If you are too far away it might be a good idea to plug in a power adapter. This controller would be great for just about anything. I will be using mine to turn my floor heat zones off and one. I will also put one in my garage to open and close the garage door. The options are endless. This module uses the DS2405, you could easily build one of these yourself. The DS2405 can also be used for input as well, so you could build a circuit that could detect if a door switch is open or closed etc...

 



The second item is called an HVAC monitor. This device has been designed to sense AC or DC voltages up to 28v. This would be great for HVAC obviously, but you could also use this to monitor a door switch or motion sensor, you may need to apply voltage to detect the changing state. I will be using this to monitor my furnace functions, but I will also use this to monitor my electric water heater. I will need to gear up a relay of some type that can handle 240v. I will talk more about this when I get it running properly. Ultimately I would like to calculate the total run time so I could calculate how much it costs to heat my floors.



Here is a picture of the temperature / humidity module. When doing the research on 1-wire stuff I found lots of web sites that talk about putting the sensors right on the cat5 cable. The sensor will work with power from the serial adapter. This is true (from what I understand), but it isn't as reliable or accurate. So I decided to just purchase some temperature modules to play with and get a feel for how things are suppose to work. If you are going to put the sensors outside or in your bathroom make sure you look at protecting the electronics from humidity. Hobby-boards will put a protect coating on if you ask.

 

I purchased some DS18S20 temperature sensors as well. I am hoping to install these into my cement bathroom floors. I will let you know how that goes.

 

 



Once I get the test network running, my first task is to get temperature sensors running. I have a couple of places that I want to monitor:

 

  1. Soda cooling lines
  2. Attic
  3. Outside
  4. Inside
  5. Unheated back room
  6. Floor heat water lines
  7. Heated floors


1-wire Links

 

 

Here is a great site about building and understanding various sensors.

www.kronosrobotics.com/Wprojects.shtml

 

misterhouse.wikispaces.com/iButton

 

www.maxim-ic.com/products/1-wire

 

www.arunet.co.uk/tkboyd/e1dsu.htm

 

The basics:

http://www.btinternet.com/~jon00/onewireintro.shtml

 

Here is a simple little project for temperature sensing:

martybugs.net/electronics/tempsensor/hardware.cgi


Please feel free to leave a comment about this page

1 Comment
#1 Itereannank wrote at 07.06.2010 19:04

Great article . Will definitely copy it to my website.

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