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.
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.
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)
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.