Arduino Plant Health Kit
This project will help you create your own plant health kit, an Arduino based device that will monitor the health of your plant and help you take care of it, including monitoring how much sun or water the plant gets, it's temperature, and helping you know when the plant needs something else.
Supplies
Circuit Design
The first step is created a design for your circuit. To do this you can take all the parts you plan on using, and create a circuit design from them. Use a breadboard to plan out your circuit with the jumper wires, as this will make testing and troubleshooting much easier.
In this project we will be using our metro mini as the brains of our project. We will then attach a photocell, speaker, LCD screen, and moister meter to the board. Be careful with all your wiring - if you make any modifications you might want to test your circuit on a breadboard to make sure everything works. The moisture sensor we use takes female to male jumper wires, so make sure to note what wires you need if you choose to use a different one.
The moisture meter we used runs on 3.3 volts, and all the other parts run on 5 volts, so make sure to keep their power supplies separate.
First thing to do is to attach the mini metro to the breadboard. You want to place it saddling the gap in the middle, so there is room in each row on ever side of it on the breadboard. Next we will wire all the components, make sure to check the diagram as you wire.
After this, the next thing to wire is the moisture meter. Looking on the back of the moisture meter you will see 5 pins, labeled analog, TX_out, RX_in, 3V, and GND. Using some female to male jumper wires, you will connect from the moisture meter to the board, TX_out to pin 11, RX_in to 10, 3V to 3V, and GND to GND1.
Next, we will wire the thermistor. Notice that it is directional. With the flat side facing you, the left pin is voltage in, the middle pin analog voltage out, and the right pin ground. Connect the ground pin GND 2 on the metro mini, voltage to 5V, and analog volatge to A0.
Next is the speaker. The speaker should have two wires coming out of it, one red and one black. Connect the black wire to GND2 on the metro mini, right next to the connection from the thermistor. The red wire connects to 5V power on the metro mini, again next to the connection from the thermistor.
Now we will wire the photocell. One end must connect to power, and the other end should go to two places. First it should have one wire going to A1, and another going to a 10K Ω resistor and then to GND2.
Finally, we will the LCD screen. For this, attach the LCD screen to one side of the breadboard, and then, following the circuit diagram, attach pins going from the LCD screen to the metro min. The 3rd wire of the LCD screen is attached to the potentiometer, and the other two sides of the potentiometer are attached to GND2 and 5V (it doesn't matter the direction, this is used for changing the brightness of the backlight of the LCD screen). This should be your circuit fully wired!
Once you have a good circuit design, you should test your design on a breadboard. To do this, you must program your Arduino to take these inputs.
Code
Now you need to program your Arduino to properly read in the sensor information, and output the state of the plant. If you have copied our circuit design, you may also use the code below, otherwise you may have to modify it slightly.
To put this code onto the Arduino, you need download and launch the Arduino IDE. Once you have that running, download the files below, and put them in a folder together. Move that folder into your Arduino folder, and open the .ino file. This should open all the files in the Arduino IDE, which you should then be able to run on the metro mini, by pressing the upload button in the Arduino IDE with the metro mini connected to your computer.
This code will print out all of the sensor outputs, so you can use that check your wireing. If everything is reading, you can then use this code to make sure things are wired correctly are you are not getting to much noise or other electrical issues.
Once you have this code running on your metro mini, it is time to wire your circuit.
Wiring
Once you are confidant your circuit and code is working, it is time to solder your circuit down to the perfboard. You may use or adapt the circuit design above. The left side is the top of the perfboard with all the wires, and the right side is the bottom side showing the soldering needed.
It is recommended that you take parts off of the breadboard and move them to the perfboard one by one, soldering while you go.
Be careful when soldering, make sure not to accidentally solder something you aren't suppose to as it is very difficult to remove.
Deployment
Now that your system is finished, it is time to use it! Find your plant, and take your moisture meter and insert it into the soil. Place the board next to the plant but in the light so the photocell can get a good reading for the light levels of the plant. A small box next to the plant would work great, or on the windowsill next to a potted plant would be another great choice. After uploading the code to your Arduino, you can power it though any power supply of your choice, we recommend a 5V micro-USB wall charger.