Wednesday, 7 January 2015

Watering system

I bought a plant, a Christmas tree ( actually two of them ), because I felt like I had to decorate my desk at work, but I was failing to water it regularly and I came up with a plan.
I decided to check on ebay for a very small and cheap pump, a soil sensor, a small arduino and few
other bits.

Wiring of transistor may change based on your model 

Pump system
The pump system was pretty straight forward, one pump, a tube and wrap it around the plant.
I decide to make holes in the tube and close the end of it, in this way the water would come out uniform and gently instead of flooding. the terrain.

In addition, I designed 4 pins to hold the tube down to the soil and point the water against the middle instead of having some random ray of water coming out of the pot.

Soil sensor
The soil sensor was the easy bit, just stick the "fork shape" into the soil and read the analog input from the chip, nothing very difficult, a part from the missing datasheet.
My chinese sensor was giving me 1024 when the soil was dry and almost zero when everything was wet.

** Note ** The soil PCB broke down after 1 week, so better if you stick two wires in the soil

I wrote down some code to make sure to trigger the pump only in a specific value, adding a delay ( in case the sensor will fail ) and a max pump time ( in case the sensor will be slow to read the current change of the soil conductivity.

Box and Tank
I had to keep everything clean and nice to look, so I designed two boxes: one to put all my electronics in and the second to keep 0.6L of water.
Very simple basic, nothing too complicated, I wanted to use a simple bottle as tank, but was very unattractive.

Source code
You can find one copy of my source code and 3d models on my github:  *** Soon ***


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