Soil moist monitor/manager and logger!

The 'what if' problem...
This project started with a LED, a moist probe and an arduino. Then I thought "what if" adding another probe? After that, "what if" adding an SD shield to log the values? 

When done, "what if"... You understand what I mean, I'm sure. 

So this ended up in a complex system as described:

- 3 Moisture probes, (max) which can be grounded (with a jumper or so) this way you can use from 1 to 3 probes as you need them. (as the one you can see in the picture)

- 3 Solenoid outputs, which will set up the watering of each probe plant (solenoid 1 will open if soil moisture probe 1 alerts for a thirsty plant.)

- 1 Digital thermometer, to log temperature.

- 1 LED.

- 1 Press button.

- 1 RTC (pointless to have a logger without date/time).

- 1 SD shield and card to retain system data.

- 1 arduino board or a DIY arduino board.

My self made board design can be viewed in the picture:

 Now, the most important, how does all this works?

You use as many probes as you want, with a maximum of 3, and connect all the devices, the system boots up, and the led will give you information about the moist:

- 2 blinks - too wet... :(

- 1 blink - GREAT! 

- Fading - too dry.

In the last state, the output pin for the solenoid will turn HIGH and open a TIP120 or a relay circuit (not done yet) to open the solenoid and then water the plant.

The time of each reading is 15 minutes, which changes to 2 minutes when a plant is dry and the solenoid opens, to assure a more accurate watering.

There is also a press button for knowing the water needs at any time, once pressed, 1 second or so later the LED gives you the information needed, not written to console nor SD card.

The logger has a format like this:

Initializing SD card... Warming up!! Starting!!!
Date    Time    Temperature    Pb1    Pb2    Pb3    V1    V2    V3    Ws1    Ws2    Ws3
2013-07-01    20:41:59    24.50    81.64    76.27    76.56     4.08     3.81     3.83    0    0    0   
 

It can be worked out in a spreadsheet or any program that deals with this kind of data, (separated by tabs). A file is created EACH month with a name like "201306.csv" which stands for the year and the month. V1, 2 and 3 are the voltage values read by arduino and Ws1, 2 and 3 are the watering status, a boolean value which is 0 or 1 depending of the watering status, 1 when watering.

I hope You enjoy this, (as I wrote, I have many flavors of this, with several combinations) now go monitor your plants, mine have never been so pretty since I started this, and though I don't have the solenoids working, the LED indications are usefull enough to get them awesome!

The code.The prototype configuration on the picture:
Used this SD library and this RTC library.      

Arduino DIY SD shield

Well... I got tired of having the arduino connected to the PC to have a logger, so did some search and ended up with this shield, it uses a micro SD card to SD converter, which is soldered to the board as you can see on picture, the components are easy to find, and they are used to low down voltage from the arduino pins (5V) to something near the 3.3V which is the correct voltage of the SD card. The red cross in the picture means you have to interrupt the circuit on those points, otherwise you would be short-circuiting the resistor. The numbers on the right (10,11,GND,3.3V,13,X,12) are the pins in the arduino board, 3.3V and GND I suppose you know what that means, and X is not connected and is used to align the plug, avoiding upside-down connections.
You can see on the left the final look, without the microSD card adapter:
And on the right side, the final look, already with the adapter soldered.

Enjoy!

 


Spoiler alert: DO NOT try to connect the card directly to arduino pins, without this voltage divider, you will damage the card!

Based on this shematic.
Test file here and another one here.