My automation in the greenhouse for this season – 2007

As we have recently moved into a new house I thought I should take a little time and investigate what would be involved in implementing a system which I could use for monitoring and automating parts of our new greenhouse as well as around our home.

If you have had a look at my previous automation page you can see that I have already played with some one wire electronic equipment and a little bit of X10, I wanted to make a larger system now though which I could keep on expanding as I wanted.

Looking at the available options for automating lights and music etc. around the home I found them to be quite expensive and not flexible enough for what I wanted to do, So I was going to have to design all the parts I wanted from scratch.

As my previous experiments with one wire items had worked well and these items are very low cost and reliable I decided I would still use dallas one wire equipment for monitoring things like the levels in my greenhouse tanks and temperatures etc.

One wire items work by interfacing to a PC or other computer via one cable, In my case I used Cat5 ethernet cable because it is low cost and contains spare cores for future use.

The first think I needed to do though was purchase a new interface to allow my PC to talk to the one wire items over a long distance. So I purchased a Link12 interface from iButtonLink, You can see this item in the photo.

This has now been working very reliably for over a year and goes along way around the house and garden. The interface plugs into the PC via a serial port. I decided to do away with a lot of the X10 equipment I had been using due to a lack of speed for turning lights on and off and also I have found it to be unreliable. Sometimes a code was missed until sent again etc. One of the problems with basic X10 is that there is no confirmation signals sent back to the transmitting units, So when this is interfaced with a PC the pc doesn’t really know if when it asks a light to turn on that it actually has. New versions of X10 have been developed to accomodate this but in the UK these are not readily available.

I do like the Radio versions of X10 though rather than the X10 which uses mains supplies for it signals.

The photo to the left is the X10 Eagle Eye Module
(Senses Motion)





X10 Stickaswitch

(Used as an instant light switch or remote control)

I already owned several Eagle eye motion detection modules and stick on light switches so I decided to purchase an enhanced X10 receiver which could interface to my PC and receive signals from light switches and motion detectors around the garden etc.

The receiver I purchased was called W800RF and was made by wgldesigns, This was ideal because it comes with antenna which was seperate from the unit and allowed me to install the antenna in the loft to get the best all round reception of X10 Radio signals.

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Automation and Monitoring the Greenhouses

This year (2004) I have started having a little play at making a monitoring system within the greenhouse, I was originally planning on using X10 equipment to automate the greenhouse. Due to the expensive nature of this equipment in the UK though I have decided to use a different method to monitor and automate the greenhouse.

dallas1While browsing the web I stumbled upon some electronic products from Dallas and Maxim called 1-Wire and iButton.

I then decided to purchase a development kit to use for this purpose.

This equipment allows you to connect sensors and switches etc. to a computer for reading and also to turn things on and off, This is all done with two wires which means the only thing I needed to connect from my house computer to the greenhouse was a small cable with two cores.

This system appears to be used quite extensively by home users who have weather stations set up, which makes it ideal for my kind of measuring and monitoring setup.

smallpc (1)I had already purchased a computer for use in the house which was to be left on all the time so I had a computer ready to use.

This computer I had was a VIA EPIA 5000 Fanless Motherboard in a tiny case, This combination only uses approximately 10 watts of electricity, Compared with 250 watts like a normal PC.

It’s also completely silent as there it’s passively cooled and there are no fans used in the computer.

The computer is connected to all the 1 wire products by a simple adaptor plugged into the serial port, This adaptor came with the development kit I purchased.

I decided that to start with I needed to be able monitor the temperature within the greenhouse (And later outside the greenhouse), Check for nutrient levels being low in the tank and also to be able to switch off and on both a heater and a fan, The products below are are the ones I chose for this purpose, All are low cost items.

1 Wire items used in the Greenhouse

DS 1820 – 1 Wire Thermometer
DS 2401 – Silicon Serial Number (Switch)
DS2405 – Addressable Switch (Fan)

floatswitchTo connect the temperature chip is simply a matter of connecting the two wire cores from the house to the legs of the chip.

To connect the low nutrient level sensor (Home made off course as you can see in the picture here.) was simply a matter of connecting the serial number chip DS2401 to the same two cores but through a microswitch. The microswitch is connected via a piece of string to a floating piece of lego which pulls the microswitch on when it starts floating to low.

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