Coffee machines are a perfect fit to build a Smart Garden, they have almost anything you need, a water deposit, a high pressure water pump and a tray on where you can grow your plants.
A smart garden is a device that can take care of the plant needs without human interaction. What do plants need? Basically water, sun and nutrients.
Coffee machines have already a water deposit and a pump, but they also heat the water, so first thing was to do disconnect the heating element, we don’t want to throw boiling water into a plant.
Disconnecting the heating element:
In order to do it I just had to disconnect and reconnect some cables, coffee machine work with domestic high volatage, 220V, so you have to know what you are doing in order.
Attaching a soil moisture sensor and a micro controller:
Because I wanted to know when to turn on the water pump I’ve attached a cheap moisture sensor to an Arduino board so I could get readings of the soil moisture level and know when to water.
Connect the water pump to a Relay:
I’ve connected the water pump to a relay, this relay was connected to the Arduino, so now we were able to turn on the pump according to the soil moisture readings provided by the sensor.
Arduino is an open source platform on where to prototype and build easily any kind of electronic projects like this one.
I decided to put some LED lights in order to provide the amount of light that a plants needs to grow, so I could place the coffee machine anyplace inside the house. It did not only make it look nicer but also the plants grew healthier with proper lighting.
Voila! We have a complete gardening device, let’s make it smart:
Well, all this was connected to the Arduino board, but then I needed to write a program to make it work all together, the code is written in Arduino and it can be found on github. I’ll avoid for now the explanation of the technical details because it’s long, but at the end you’ll find an introduction to it.
After several versions I’ve decided to attach a Bluetooth receiver to the Arduino board, so I could modify the parameters like Daily hours, Watering time, etc, on the run. To make it possible I bought a very cheap bluetooth module, the HC-06 Bluetooth and connected to the Arduino, then I build a web interface to access to modify the parameters of the program I wrote:
To make possible to interact on the run with the coffee machine I’ve design a Browser Accessible Interface were to have a bluetooth connection with the coffee machine, so I could modify the parameters from my computer without having to physically access to the Arduino board.
With this, I was able to turn on and off the lights anytime I wished, also, I was able to water manually or modify the parameters of the automatic watering system I build. The interface can be accessed here:
I’ve also added some charts to have a little history back up of what was going on anytime, the implementation of this part is still uncompleted.
I found this old coffee machine in my workplace, it was abandoned on the office basement for several years: a very expensive Italian machine, made of steel, with a shiny and nice retro looking, it kept my attention early.
After a couple of years growing dust I’ve asked permission to try to fix it, keep it or throw it away. So I brought it home, when I first tried it making a coffee was impossible: it was leaking hot water. It didn’t look so bad so I’ve checked it all and I’ve contacted the company to provide new spare parts for it: I bought a new gasket and couple of new filters and fixed! The machine was making coffee again!
It was noisy, slow and dirty but after some calibration the coffee started to be real good, I was very proud of my new coffee machine, it made coffee for some weeks, but soon it started to leak from the same gasket. Holy crap.
When fixing it I’ve noticed some marks, it was crystal clear that someone already tried to fix it before, I guess they had the same luck and this was obviously the reason it was abandoned there.
I think the machine suffered from overheating, so after some service the sealing gasket was warped again and leaking. I though on ways to fix it, certainly the machine looked nice, but still, I really preferred my old and cheap filter coffee machine, it may be ugly, but it’s more efficient, clean, and I really prefer weak watered-down coffee.
So as I didn’t know what to do with it I took the coffee machine and left it at the entrance of my house waiting to be thrown away, and it remained there growing dust for many, many months, like half year, sitting at the entrance of my little flat. What was doing there? I did not know either.
On a very hot day of this last summer I was absolutely bored at home, I saw this old coffee machine and I though, mhm, okey, today we’ll do something with you, and so, this is the story of how to turn a coffee machine into a Smart Garden, a Plantbot.
Materials used:
// ANALOG INPUTS PIN DEFINITION//
int moisture_sensor = A2;
// DIGITAL INPUTS PIN DEFINITION//
int lights_p = 11; // Lights relay
int pump_p = 10; // Water pump relay
int moisture_p = 8; // Moisture sensor relay
The default modifiable global control parameters are as follow, all this parameters can be modified on the run using the Browser Bluetooth interface I’ve created.
int hoursLight = 14;
int hoursDark = 10;
int min_moisture=42;
First two parameters control the day duration and light and dark hours for each day, this may need to be modified to satisfy plant photoperiod needs, for an introduction on plant lighting needs visit this link.
Third parameter: min_moisture sets the threshold value that will turn on the watering system.
The watering routines are simple:
Control variables:
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