The controller is made using an Arduino microcontroller with a 'Wi-Fi shield' and a 'data logger shield' stacked on top, along with a 5V DC / 24V AC power supply and a relay board. On the lid you can see the terminal blocks where you connect the wires from the solenoid valves and any wired soil moisture alarms you have installed.
Below is a photo of my first prototype using an off the shelf box. However is impossible to find an off the shelf box that is the right size, made from non-metallic material and with a hinged lid rather than a lid with screws. The problem with this design was that access to the SD card and batteries was difficult and risks accidently disconnecting wires.
I have since worked on a custom enclosure made from pine and this proved to be a far better design that allows easier access to the SD card and batteries etc. The wood is oiled with linseed oil so it is water resistant, but I wouldn't install the box any where that it will receive frequent or heavy rain because the lid for the box does not seal.
A partial cover hides all the connecting wires and thus reduces the risk of accidental disconnection of any of them. So only the system clock batteries are exposed along with the connection points for the solenoids and the wired alarms. Not shown here is a hinged door that hides all of this.
Third prototype: based on matrix board but set out like a Printed Circuit Board (or PCB)
The device has been tested for the past several months and both the software and the hardware is stable. In the above photo a real solenoid is connected to station 2 for testing purposes. There is a small hole in the side of the case adjacent to the terminal blocks and, when you install the device, you would pass an Ethernet cable through that hole and connect each of the 4 twisted wire pairs to one of the terminal blocks (each containing 2 screw clamps). If using all 8 stations you would need 2 lengths of Ethernet cable, each containing 4 twisted pairs of wires each. One twisted pair of wires is required to connect one solenoid valve.
At some point I may have to look into having these devices manufactured with a custom circuit board and plastic enclosure. However, for the time being, it makes more sense to simply hand make the devices from off the shelf components.
And here is the final prototype with a professionally made PCB and an electronics project box and from Jaycar.
- Wi-Fi enabled with a web page interface: type the controller's IP address into the address bar of your web browser and the device's user interface will be presented to you from the comfort of your office or lounge room.
- Accessible while you are at work or on holidays: for this you will need either a static IP address from your Internet Service Provider, or you will need to set up an account at https://duckdns.org (or any other Dynamic Name Server service provider) and you will need to make some changes to the settings of your ADSL modem. Detailed instructions are provided.
- A total of 8 irrigation stations are provided.
- Suspend irrigation: the ability to suspend irrigation on each station between specified dates, which is handy for wet winters or summers.
- Irrigate daily, weekly or even monthly: you can irrigation individual stations every second day, once a week, every three weeks or every two months(useful for a succulent garden).
- Wired soil moisture alarms: soil moisture is determined through the conductivity of the soil - the wetter the conductive it is. Each station can have its own soil moisture probe installed or not. If it is installed you can specify a conductivity threshold value and a time (in minutes). If the conductivity of the soil remains below the threshold for more than specified number of minutes then the system will warn you via email. There is also an option to have the station automatically switch on for a specified number of minutes if an alarm is triggered.
- Manual control: you manually turn on stations from any remote location via the web.
- Time synchronising: the system synchronises the Real Time Clock with the official world time at Greenwich in Britain, on boot up and once per week.
- Time zone: the system allows you to specify the time adjustment (from Greenwich Mean Time) for your time zone, so the controller can be used any where in the world.
- SD Card: all the system data is stored on a micro SD card so it wont matter if there is a power loss - the system will simply re-boot, read all the system data back from the SD card and continue on as normal. Unlike conventional irrigation controllers that must be re-programmed if the back up battery is also flat at the same time as the power loss.
- Bluetooth interface: the system also has a Bluetooth interface that you connect to via a simple android phone app. This allows you to enter your Wi-Fi network name and key into the system so that you can then access it via your web browser.
You can connect any standard 24VAC solenoid valve to the controller.
- If you want to try one out before you buy it then visit irrigation.duckdns.org:10002.
- This is a physical device sitting on my desk that is port forwarded to provide external access to the settings.
- Password checking is disabled so you can enter any old text as the password.
- 'Duckdns.org' allows you to setup a permanent URL to access you device even though you have a dynamic (constantly changing) public IP address with your internet service provider.